MENINGEAL CYSTS
Amongst the pathological conditions responsible for the development of epilepsy, chronic cephalalgia, &c., meningeal cysts must be regarded as of frequent occurrence.
Traumatic meningeal cysts are varied in size, site, and structure. They may be classified as follows:—
| 1. Cysts within the calvarium. | Between the dura and the bone. |
| Between the dura and the brain. | |
| Within the brain-substance. | |
| 2. Cysts projecting through a gap in the calvarium (traumaticcephaloceles). For a description of these cysts the reader is referredto [p. 40]. | |
Cysts within the calvarium.
Traumatic cysts within the calvarium, whatever their situation, may be divided into two definite groups:—
1. Where the cyst possesses fibrinous walls (in which hæmatoidin cysts may be deposited) and contains a grumous material. These cysts are usually subdural in position, are dependent on the previous existence of a hæmatoma, and are known as ‘blood-cysts’.
2. Where the cyst—often of considerable size—is lined by a thin, shiny, membranous wall. The contained fluid is almost colourless, closely resembling cerebro-spinal fluid, but albuminous and having no sugar-reducing reaction. The fluid is at high tension, spurting out when the cyst is punctured. The cyst usually lies in relation to the arachnoid membrane. Hence the name, ‘arachnoid cyst’.
To account for the development of these ‘arachnoid cysts’ two theories have been advanced. Firstly, that they arise as the ultimate result of a long-continued circulatory disturbance of the vessels of the membranes or of the cortex, with consequent local cystic accumulation of cerebro-spinal fluid or serum; and secondly, that shrinking of the brain occurs in the region of an injury as the result of sclerotic changes in the cerebral substance, any contraction tending to lead to the formation of a vacuum which becomes filled with fluid derived from the surrounding membranes. According to this latter theory, arachnoid cysts are in reality ‘cysts ex vacuo’.
As regards symptomatology, little need be said. Occasionally ‘arachnoid cysts’ of considerable size have been discovered at post-mortem examinations which appeared to have exercised no local or general pressure effects during life. More often the cysts, whether ‘blood-cyst’ or ‘arachnoid cyst’, lead to the development of Jacksonian epilepsy, chronic headache, and the like, and are discovered during the exploratory operation carried out for such conditions. Occasionally they may be shelled out entire, but it is more usual for the surgeon to remain content with the removal of the parietal wall (see [p. 195]). The results obtained by surgical treatment are sufficiently gratifying.
TRAUMATIC ORBITAL ANEURYSM
(Pulsating Exophthalmos)
This condition was first investigated by Rivington in 1875. Since that date many other cases have been reported, and the following remarks are based on the examination of the records of 26 cases, 2 of which have come under my own care.
The nature of the trouble, the results obtained by operative treatment, and the direct evidence supplied by post-mortem examination furnish sufficient proof to justify the statement that the symptoms are dependent on the formation of an arterio-venous aneurysm, the internal carotid artery and the cavernous sinus intercommunicating by means of one or more fistulous channels. That such a lesion may arise from direct violence—the introduction of some sharp weapon along the upper and inner portion of the orbital cavity—-is readily comprehensible. Such injuries are, however, of rare occurrence, and the formation of the aneurysmal communication is usually the result of indirect violence—the application of severe blows to the antero-lateral and lateral aspects of the head.
In explanation, the following preliminary facts may be accepted:—
In the great majority of cases the blow was applied to the temporal region, the patient was rendered unconscious, bleeding freely from the ear, nose, and mouth, and remained under treatment for some considerable time. From these facts it may be assumed that the patient suffered from a fracture of the base of the skull—anterior or middle fossa, or both fossæ. Evidence has already been brought forward to show (1) that the majority of fractures involving both anterior and middle fossæ traverse the body of the sphenoid, and (2) that the cavernous sinus is very susceptible to injury. It was also demonstrated that the internal carotid artery is only liable to injury in that part of its intracranial course where it is embedded in the outer wall of the cavernous sinus. Two instances of such a lesion have been described in the section dealing with injuries to intracranial vessels (see [p. 148], and [Figs. 53] and [54]).
From these facts and from the post-mortem evidence supplied by the few cases that have come to autopsy, it may, I think, be concluded (1) that traumatic orbital aneurysm implies a condition of arterio-venous aneurysm with direct communication between the internal carotid artery and the cavernous venous sinus, and (2) that the aneurysmal formation is dependent on a basic fracture which traverses the region of the body of the sphenoid bone.
The exact nature of the communication between the two vascular channels may be estimated from the fact that proptosis—usually the first symptom to make its appearance—seldom becomes apparent till one or two months have elapsed after the accident. It would appear, therefore, probable, that the artery is not ruptured but merely weakened at the time of the injury, the weakened arterial wall gradually giving way before the force of the blood-stream till a definite communication is formed between the two channels.
The male sex, by reason of its greater liability to severe injuries, is generally the one involved, especially between the ages of 20 and 30.
Symptomatology.
1. Proptosis
—usually the first symptom to develop—seldom makes its appearance till after the lapse of one to two months. The eyeball is protruded in the downward and outward direction, the main pulsating tumour presenting at the upper and inner quadrant of the orbit. Proptosis is generally steadily progressive, and, in the most marked cases, the globe may be almost pushed out of its socket. In any case the ‘whites’ of the eye are unduly prominent.
2. Aneurysmal symptoms.
The tumour pulsates synchronously with the heart’s beat, whilst compression of the common carotid of the same side results in cessation of pulsation and great diminution in the size of the aneurysmal swelling. On releasing the compression force the tumour regains its original size in two or three beats of the heart, and, for a short time, pulsates more forcibly than before. A definite thrill is imparted to the examining finger, and, on auscultation, a loud murmur is heard, not only over the tumour itself, but also widely conducted over the bones of the vault, especially along the line of the superior longitudinal sinus. The free collateral circulation between the angular and ophthalmic arteries permits of the involvement of vessels in the inner orbital and upper nasal regions. This is well shown in the case depicted in [Fig. 61].
Fig. 61. A Case of Traumatic Orbital Aneurysm.
3. Pressure symptoms.
The impairment of venous flow in those radicles which drain into the cavernous sinus is evidenced by the marked engorgement of palpebral, conjunctival, episcleral, and retinal veins. Obstruction to lymph flow is shown by a hazy cornea, chemosis, and œdema of the parts surrounding the orbit. The danger thus incurred by the cornea is rendered more serious by the inability on the part of the patient to close the eyelids over the protruded globe. Keratitis and sloughing of the globe are to be feared. From muscular involvement, squints and diplopia are frequently observed. The pupil may be fully dilated through paralysis of the third nerve.
4. Subjective symptoms.
Defect in vision is experienced at an early date, but perhaps the most prominent subjective symptom lies in ‘noises in the head’, compared by the patient to the thud of a steam-hammer, the whirring of wheels, the buzzing of bees, &c. These noises are more or less constant, most annoying to the patient, and increased on bending down, straining, &c.
All these symptoms tend to become more severe as time lapses, though cases have been recorded in which the symptoms remained in statu quo. In the event of failure at relief or cure, the patient runs considerable risk of losing his sight from corneal ulceration, whilst repeated hæmorrhages and secondary infection may place the patient in imminent danger of his life.
Treatment.
In the consideration of the treatment of this condition, the results obtained in the 26 cases investigated will afford a valuable guide.
In 4 cases an expectant attitude was adopted, the patient being kept quiet, restricted in diet, and dosed with potassium iodide. One case improved, two experienced no material benefit, and the fourth, dissatisfied, discharged himself from the hospital.
In 10 cases compression was applied to the common carotid artery, with the result that in 3 cases the conditions remained stationary whilst in the remainder, either on account of the pain produced or from complete failure to bring about any improvement, this mode of treatment was abandoned in favour of ligature of the common carotid. In some cases the carotid compression was carried out by means of tourniquets, in others intermittent digital pressure was utilized by means of relays of assistants.
In 18 cases the common carotid was ligatured, in 12 cases as a primary measure, in 6 after failure of other methods. The immediate and remote results were in all cases as satisfactory as could be anticipated. Proptosis at once diminished, the globe receding in some cases to the normal position, and the distressing subjective symptoms were almost entirely relieved. In many cases the patients were enabled to return to work.
Some defect in vision commonly persists, dependent on muscular paresis (on account of the previous stretching), retinal thrombosis, or corneal changes. The longer radical treatment was deferred the greater and more distressing were the after-effects of the lesion.
According to Sattler, however, the results obtained by ligature of the common carotid are less favourable than as stated above, and by no means devoid of danger to life. Fifty-six cases were collected with results as below:—
39 cases recovered and showed marked improvement.
11 cases experienced no benefit.
8 cases died.
It has been urged that ligature of the internal carotid artery would suffice to bring about equally satisfactory results, combined with less danger to life and diminished risk of secondary cerebral degeneration. Such, however, does not seem to be the case, for the anastomosis between the angular arteries and between the terminal branches of the ophthalmic is so free that the results obtained by ligature of the internal carotid appear to be unsatisfactory. Indeed, even when the larger trunk was tied, secondary operations have been occasionally required in order to excise some large anastomotic channel in the region of the inner canthus of the eye and over the bridge of the nose.
From these data, the following conclusions can be drawn:—
1. That by means of rest, careful dieting, and administration of potassium iodide in large doses, the progress of the case can sometimes be arrested, but that much patience is required and the ultimate result is entirely problematical.
2. That compression—digital or instrumental, intermittent or continuous—is painful, tedious, and usually quite inefficacious.
3. That ligature of the common carotid affords the best chance of cure or alleviation.
When should the common carotid artery be ligatured? How soon after the development of symptoms? This depends largely on the severity of the accident that produced the arterio-venous communication. If the blow was severe and the depth and duration of the stage of unconsciousness of a prolonged character, it may be presumed that the brain was injured. Under such circumstances early ligature of the common carotid presents an appreciable danger by reason of the development of hemiplegia on account of the further interference with the arterial supply to the brain. In such cases the patient should be confined to bed or kept quiet for not less than two months, the operation being carried out when the general condition warrants surgical interference.
In the event of early operation being imperative, periodic digital compression of the common carotid, for a few minutes at a time, may be carried out with the object of accustoming the brain to the proposed new form of circulation. In ordinary cases the sooner the common carotid is tied the better is the ultimate result.
[36] Hunterian Lectures, February 1904.
[37] It is absolutely essential that the scalp incision should lie some distance away from the outer margin of the plate. Failure to adopt this procedure impedes the healing of the wound and adds to the risk of infection.
[38] If desired, the plate may be anchored in position by means of a few small silver-plated screws.
CHAPTER VII
TUMOURS OF THE BRAIN
Tumours of the brain.
Tumours may develop in any part of the cerebrum and cerebellum, from the sheaths of the efferent nerves, from the vascular tissues, and from the membranes of the brain. Tumours arising from the bones of the skull are considered elsewhere (see [p. 325]).
The regional distribution of these tumours may be estimated by reference to the following table[39]:—
| Cerebellum | 33 | cases. |
| Deep or subcortical | 32 | „ |
| Precentral | 30 | „ |
| Post-central | 25 | „ |
| Extra-cerebellar | 19 | „ |
| Pontine | 15 | „ |
| Temporo-sphenoidal | 13 | „ |
| Multiple | 7 | „ |
| Fourth ventricle | 5 | „ |
| Third ventricle | 4 | „ |
| Pituitary | 2 | „ |
Schüster,[40] from an investigation of 1,000 cases, showed that cerebellar tumours are relatively more common than cerebral, the comparative size of the two regions being taken into account. An examination of Paton’s table shows that cerebellar and extra-cerebellar tumours together form rather more than 25 per cent. in 202 cases of brain-tumour formation.
Pathology.
Gliomata, sarcomata, and endotheliomata are the three commonest types of tumour formation. Other forms are fibromata, tuberculomata, syphilomata, cysts, and carcinomata.
Fig. 62. A Glioma of the Brain.
Fig. 63. A Sarcoma of the Brain.
Gliomata
occur with almost equal frequency in cerebrum and cerebellum. They are generally primary and single, the boundaries but ill-defined, and the tumour is seldom amenable to radical surgical procedures.
Fig. 64. An Endothelioma of the Dura Mater.
Fig. 65. A Fibroma of the Dura Mater. Indenting the cortex and attached to the pia-arachnoid by fine filaments.
Sarcomata
grow from the meninges, periosteum of cranial bones, and from the sheaths of nerves and vessels. They are either primary and then single, or secondary and then multiple (sarcomatosis). Sarcomata are often more or less encapsuled, tending in the first instance to exercise a compression force, and only in the later stages to invade the surrounding regions. It is during this early stage of development that the tumour is capable of removal.
Fig. 66. An Acoustic Tumour. Attached loosely to the seventh and eighth nerves.
Endotheliomata
grow from the meninges of the brain. They are hard, nodular, and, in their early stages, definitely non-infiltrating, and, when accessible, removable.
Fibromata
are especially prone to originate in the cerebello-pontine angle, usually possessing a narrow stalk representing an atrophied nerve-trunk or vascular bundle. From the frequency with which these cerebello-pontine tumours are attached to the eighth nerve they are often designated acoustic tumours. They may be as small as a pea or as large as a hen’s egg. In their early stages they are probably pure fibromata, appearing as pink-red lobulated tumours. They are of slow growth, primarily compressing the brain-substance without invasion. Later on degenerative changes are prone to occur, with invasion of the cerebellar substance and extension into the internal auditory canal. Whether growing in the cerebello-pontine angle or in other parts of the skull, fibromata are often readily removed.
Fig. 67. Symmetrical Tuberculomata. Situated on either side of the falx cerebri above the tentorium cerebelli.
Tuberculomata
are most commonly situated beneath the tentorium. They are often multiple. They cannot be considered as favourable tumours from the surgical point of view, insomuch as they are frequently associated with tuberculous lesions in other parts of the body and complicated by a tuberculous infiltration of the meninges.
Syphilomata
occur with greater frequency in the cerebrum than in the cerebellum. Sometimes they are totally unaffected by anti-syphilitic remedies, and, under such conditions, appear as densely hard and definitely encapsuled tumours. These more chronic gummata are usually cortical or subcortical in position, and, when accessible, are readily removable.
Cysts
are of frequent occurrence. They may be (1) of traumatic origin, containing a grumous material characteristic of the incompletely absorbed blood-clot; (2) of parasitic origin (e. g. echinococcus); (3) due to cystic degeneration of a sarcomatous, carcinomatous, or gummatous mass; or (4) simple arachnoid cysts (see [p. 203]). Many of these cysts are amenable to surgical treatment.
Carcinomata
are always secondary to cancer in other parts of the body—more especially carcinoma mammæ. They are usually multiple, and quite unsuited to surgical procedures.
Any of these tumours may be complicated by the presence of internal hydrocephalus, this condition being dependent on the pressure exercised by the tumour on the veins of Galen, or on the interference with the normal transudation of fluid from one ventricle to another.
Symptomatology.
The symptoms resulting from tumour formation may be considered under two headings:—
1. General symptoms, dependent on the general increase of intracranial pressure.
2. Localizing symptoms, dependent on local compression.
Previous to discussing the symptomatology of brain tumours, it cannot be too forcibly urged that the surgeon is seldom justified in embarking on an extensive operation for tumour removal except after consultation with a neurologist. Ill-planned and ill-timed operations are usually disastrous in their results, and little creditable to cranio-cerebral surgery in general. On general grounds also, the symptomatology of brain tumours, as given below, must be accepted in the light in which it is offered, not representing the complete neurological aspect of the case, but affording an index to general diagnosis. For further information the reader is referred to more extensive works on brain tumours.[41]
I. General Pressure Symptoms
Headache.
Mental disturbances.
Optic neuritis, &c.
Vomiting.
Alterations in pulse, respiration, and blood-pressure.
Alterations in temperature.
Headache.
Headache is an almost constant symptom, and presumably dependent on general or local dural tension. It may be general or localized, intermittent or continuous, intense or comparatively mild in character. It is the more intense when the tumour develops in the confined space of the subtentorium, and when the tumour is of considerable size. In young subjects, before the skull is synostosed, some compensatory enlargement of the skull may postpone the development of headache, or diminish its intensity.
The diagnostic value of a localized headache is rather problematical, but, when constantly referred to some particular region and when associated with definite tenderness on percussion, the localization of the headache assumes considerable importance in the regional determination of the tumour. Still, too much stress must not be placed on the site of the pain. A cerebellar tumour may give rise to frontal headache, and vice versa.
Mental disturbances.
In the earlier stages of tumour development the patient is irritable, depressed, or apathetic, shows his objection to his fellow mortals on all possible occasions, is unable to concentrate his attention or exhibits impairment of memory. As has rather quaintly been observed, he appears in every sense to ‘have a weight on his mind.’ Inquiry amongst relatives will show that he has ‘changed in every way’, or ‘is not the same man’.
Mental changes vary according to the site and size of the tumour. For example, it has been stated that a general air of elation or exhilaration (Witzelsucht) may be regarded as almost diagnostic of tumours situated in the anterior part of the frontal lobe.
As the tumour increases in size, somnolence becomes the marked feature, progressing on to stupor and coma. In rare cases, mania may develop.
Optic neuritis.
Optic neuritis must be regarded as one of the most constant and valuable symptoms in the diagnosis of intracranial tumour formation. The degree to which it progresses depends more on the site of the tumour than on its size. In general, it may be stated that it is most constantly associated with tumours of the temporo-sphenoidal and cerebellar regions, less common in frontal tumour formation, still less frequent in post-central tumours, and perhaps least common in tumours of the pons. In this last-mentioned case optic neuritis is always late in development, and not infrequently absent throughout the whole stage of the illness.
Primary optic atrophy only occurs when the tumour exerts direct compression on the optic chiasma and tracts—for example, pituitary tumours.
Paton,[42] from a series of 252 cases treated at the National Hospital, of which 202 were accurately diagnosed, found that optic neuritis or atrophy was present in 81·2 per cent. cases. The fundus change, though usually bilateral, may be confined to the ipso- or contra-lateral side. Considerable discussion has taken place as to the localizing value of unilateral disk changes. For instance, it has been stated that a unilateral neuritis indicates that the tumour is situated on that side of the brain, and that when disk changes are bilateral the side which evidences the higher grade of inflammation is the side on which operation should be conducted. In the light, however, of the most recent research it would appear that unilateral symptoms are not to be relied on in establishing the localization of the tumour. Gowers[43] lays stress on the statement that with strictly unilateral neuritis one should always suspect a general rather than a local exciting cause.
The actual cause of the neuritis is still a matter of doubt. It is possible that the same cause is not present in every case. Still, sufficient evidence is to hand to justify the probability that neuritis is dependent on the general increase of intracranial pressure—there is, at any rate, a close relationship between the two. The cerebro-spinal fluid is forced into and dammed up within the vaginal sheaths of the optic nerve, leading, in the first instance, to an œdema, and later on, to compression of the lamina cribrosa and interference with the circulation.
The increase of intraventricular pressure may also act directly on the optic tracts and chiasma—the anterior boundaries of the third ventricle—the pressure being then transferred directly to the nerve tracts.
Furthermore, the great intensity, great frequency of occurrence, and rapid development of optic neuritis when the tumour is subtentorial in position may be explained on the hypothesis that the rigid enclosure of the cerebellum permits of the ready application of pressure to the veins of Galen or to the iter, thus leading to an increase of intraventricular pressure, this pressure being then transferred to the optic region.
The alternative theory states that the old tissue destruction and the new tissue formation sets free certain toxic substances which act on the optic nerve-fibres, leading to œdema and inflammation. Paton, however, comes to the conclusion that ‘the nature of the tumour does not play any part in determining the onset of neuritis except in so far as the nature determines its localization’.
Whatever be the localizing value of optic neuritis, it is generally accepted that it commences in the upper nasal quadrant.
Visual acuity is but little impaired in the earlier stages of optic neuritis, but so soon as atrophic changes develop, diminution in the field of vision occurs.
The pupillary changes associated with tumours of the brain are closely connected with these fundus changes. In the early stages, the pupils may be contracted with the object of protecting the inflamed surfaces exposed to light, whilst, when atrophy develops, the pupils may steadily dilate, becoming fully dilated and fixed as the atrophic changes become fully developed.
These pupil changes must therefore be taken into consideration in estimating the value of pupillary changes in general.
Vomiting.
Vomiting is dependent on stimulation of the medullary vomiting centre, or on irritation of the dura mater in the immediate neighbourhood of the tumour. The dura is supplied by branches of the fifth cranial nerve, the stimulus being referred to the vagus centre in the floor of the fourth ventricle.
Vomiting is of the so-called ‘cerebral’ type. It is of frequent occurrence, generally irrespective of ingestion of food and seldom preceded by any nausea and retching. The attacks are often associated with exacerbation of headache, and more rarely with some slight elevation of temperature. The more severe the vomiting the more likely is the tumour to be subtentorial in position.
Alterations in pulse, respiration, and blood-pressure.
In the early stages there is but little alteration in pulse and respiration. Later on, the increasing intracranial pressure acts as a stimulus on the vagus and vaso-motor centres, the pulse becomes slowed and the blood-pressure raised. When the pressure is considerable, the slow pulse and deep, even stertorous, respiration evidence the effect produced on the medullary centres. In the terminal stages the imminent exhaustion of these centres is heralded by progressive acceleration of the pulse, by great fall in blood-pressure, and by the advent of Cheyne-Stokes respiration.
The more marked the alterations in pulse and respiration the more likely is the tumour to be subtentorial in position.
Alterations in temperature.
The temperature tends to remain subnormal throughout the progress of the case, except during the terminal stages when pyrexia is often observed. Occasional elevations of temperature during the course of the illness may be explained by transient attacks of ependymitis or cerebritis.
Differences of temperature on the two sides of the body may occasionally be observed, especially when the tumour involves the basal ganglia.
II. Localizing Symptoms
(A) To the non-excito-motor frontal region (anterior frontal).
Headache tends to be localized to the frontal region, vomiting is seldom a conspicuous feature, and optic neuritis is not only rather later in development, but also less progressive than when the tumour is placed in other situations. If the tumour occupies the orbital aspect of the lobe, primary optic atrophy (from pressure) may be existent on the affected side with optic neuritis of the contralateral fundus.
The mental condition is often profoundly altered and, according to some writers, more especially so when the tumour is situated on the left side. The quality of mental change varies considerably in individual cases. In some there is an attitude of general suspicion, the patient following all points in his general examination with a curious air of suspicion, in others moral perversion is the rule, whilst in a third group of cases a state of elation and exhilaration is the predominant feature, a condition which, as previously stated, is said to be pathognomonic of a tumour frontally situated.
Anosmia—uni- or bi-lateral—may be present, but, on account of the general condition of the patient, considerable difficulty is experienced in endeavouring to demonstrate the existence of this symptom.
Fig. 68. The Cortical Motor and Sensory Areas.
Incontinence of urine has been observed, independent of the condition of the patient—in other words, without a sufficient degree of coma to account for the state.
When the tumour is of considerable size, some degree of paresis of the contralateral side of the body may result, due to backward pressure exercised by the tumour on the corona radiata preceding from the pre-Rolandic motor area. Associated with this paresis the deep reflexes may be increased with extensor plantar reflex (Babinski) and some diminution of superficial reflexes. The more posterior the tumour the greater the degree of paresis, and the more exaggerated the reflexes. When the tumour is situated on the left side the motor speech centre may be affected.
Fine tremors may be noticed, usually involving the muscles of the upper extremities, and best demonstrated by asking the patient to hold his arms horizontally with the palms downwards.
Paresis on the contralateral side may be preceded by or associated with fits, these partaking of the Jacksonian type and accompanied by conjugate deviation of the eyes towards the side opposite to that on which the tumour is situated. This association of fits suggests that the tumour occupies the second frontal convolution.
(B) To the excito-motor frontal region.
In the early stages symptoms of irritation predominate, the patient suffering from fits of a focal or Jacksonian type (see [p. 189]), whilst, later on, paresis of a progressive type, involving the face or extremities unequally, becomes evident. In children, however, the rapid transference of impulses from one motor area to another causes the fits to soon lose their focal character, general convulsions taking their place.
If the tumour occupies the left side of the brain (in right-handed individuals) the motor speech centre of Broca may be involved, with difficulty in or failure of the power of speech.
Apraxia may be present, a condition characterized by inability on the part of the patient to perform certain familiar purposive movements, such as sewing, turning a key in the lock, &c.
The contralateral pupil may be contracted from irritation, or dilated from paralysis; the ipsolateral is variable, more commonly dilated.
In the event of extensive tumour formation and when the growth is associated with tract degeneration, the deep reflexes will be increased on the contralateral side, with well-marked extensor plantar response.
(C) To the post-central, angular, and marginal convolutions.
Attacks of focal epilepsy are frequently observed when the tumour occupies the post-central convolution, such developments being probably dependent on forward pressure effects. These epileptiform attacks, however, are almost invariably preceded by some sensory auræ. Furthermore, the fits will usually be followed by ‘some degree of anæsthesia or analgesia, a loss of tactile sensation over half the body, affecting mostly the hand and foot, with loss of power and astereognosis (inability to recognize the form and consistency, and to name objects placed in the affected hand)’ (Beevor).
When situated in the left angular gyrus, word-blindness may result—inability to appreciate the meaning of written words, &c.
When the tumour presses on the optic radiation, hemianopia results, with ipsolateral temporal and contralateral nasal blindness.
(D) To the temporo-sphenoidal lobe.
When the tumour occupies the anterior part of the temporo-sphenoidal lobe, more especially when it is situated on the internal aspect of that lobe, the degree of optic neuritis is intense. Perversion or loss of smell may be noticed—a symptom of difficult determination on account of the general condition of the patient.
As the result of pressure exercised on the optic tracts hemianopia—with hemianopic pupillary reaction (the pupil not reacting to light)—may be observed. Pupillary reactions, however, are complicated by possible paralysis of the third nerve.
Some weakness of the face muscles on the contralateral side is a fairly constant symptom, presumably dependent on the upward pressure exercised on the lower motor areas.
A tumour involving the more posterior and central portions of the lobe may bring about a certain degree of word-deafness, whilst objects may be incorrectly named or named with difficulty, the patient being more or less aware of his mistakes and evidencing considerable annoyance of the same.
In whatever part of the lobe the tumour be situated, certain sensory auræ may be present. Not infrequently the patient falls into the so-called ‘dream-state’. When sensory auræ are associated with crude sensations of smell and taste, with chewing or spitting movements, the tumour is probably situated on the antero-internal aspect of the lobe.
(E) To the occipital lobe.
Headache may be localized to the back of the head, and optic neuritis is usually both early in onset and intense in degree. Perhaps the most important localizing symptom is homonymous hemianopia—blindness in the temporal half of the retina on the same side as the lesion and in the nasal half of the opposite eye. This is explained by the fact that the fibres of the optic radiation, passing forwards from the affected occipital region, supply those retinal areas. The reaction of the pupil will be unaltered, for the pupillary nerve-fibres, in their course towards the third nerve nucleus, are only directed backwards as far as the anterior corpora quadrigemina. Consequently, an interruption of optic fibres between retina and third nerve nucleus brings about a loss of pupillary reflex when light is thrown on the blind portion of the retina, whilst if the lesion be situated further back, pupillary reaction is unaltered. This is Wernicke’s sign.
(F) To the subtentorial region.
Certain symptoms are more or less common to all subtentorial tumours, whether they arise within the cerebellar substance (intra-cerebellar) or immediately outside the brain-substance (extra-cerebellar). Headache is very severe, and in about 50 per cent. cases, localized to the back of the head, perhaps associated with stiffness of the neck muscles and retraction of the head. Optic neuritis is early in onset and intense in degree. It is more constant in cerebellar tumour formation than in tumours located in almost any other part of the brain. The choking of the disk is marked and hæmorrhages are frequent. Vomiting and other symptoms referable to increased subtentorial pressure—slow pulse, altered rhythm of respiration, &c.—are usually well marked.
Fig. 69. The Visual Paths. O.L., Occipital lobe; O.R., Optic radiation; O.T., Optic tracts; P., Pupillary fibres from optic tract to third nerve nucleus; O.C., Optic chiasma; O.N., Optic nerve; 1, Blindness of affected eye; 2, Bitemporal hemianopia; 3, Bilateral homonymous hemianopia, with hemianopic pupillary reaction; 4, Bilateral homonymous hemianopia, pupillary reaction normal.
Vertigo is most apparent when the patient is suddenly changed in position or tries to stand or walk. It appears in two forms, either as a definite sense of movement of self (subjective vertigo) or of objects (objective vertigo), or merely as a giddy feeling. In objective vertigo the sense of displacement of objects is more commonly from the side of the tumour towards the sound side.
Vertigo is dependent on the influences exercised by the tumour on the cerebello-vestibular apparatus, and on irritation of those branches of the fifth nerve which are distributed to the dura mater in the immediate neighbourhood of the tumour, the impulses being then transferred to the bulbar nuclei of that nerve and thence to the pneumogastric nucleus.
Ataxia and inco-ordination of movement are also prominent symptoms. Ataxia results from one or more of the following causes: (1) co-existent vertigo, (2) asthenia of the muscles of the affected side, the muscular contractions being irregular in their nature, ill-timed in their action, and often in excess of actual requirements, and (3) involvement of the spino-cerebellar tracts and their terminations.
The patient, when standing with the eyes shut and one foot advanced in front of the other, is unable to maintain his balance, staggers and tends to fall. No great diagnostic value can be attached to the direction in which he sways or falls, though, from my own experience, it would appear more probable that he should lurch towards that side on which the tumour is situated. In walking, however, there is occasionally a definite tendency to deviate towards the opposite side, probably due to over-correction of the weakened muscles on the affected side. The gait should present the typical appearance of cerebellar ataxia, and the patient may walk with the head drawn down towards the shoulder of the affected side, the chin being tilted in the opposite direction.
Inco-ordination of movement is rendered most obvious during active movement of the limb, decreasing towards the termination of that movement, and ceasing so soon as the object is attained. This is most readily demonstrated by the well-known ‘finger-to-nose’ test.
Nystagmus is one of the most frequent symptoms of cerebellar tumour, usually lateral, the movements coarse or fine, and most marked when the eyes are directed towards the side of the lesion.
In the more differential diagnosis between extra- and intra-cerebellar tumours, the following points should be noted:—
Extra-cerebellar tumours situated in the cerebello-pontine angle tend to lead to compression of the eighth nerve (with deafness and tinnitus), of the seventh nerve (with paralysis of the face muscles), of the fifth nerve (with anæsthesia of the parts supplied by that nerve), and more rarely of the sixth nerve (with paralysis of the external rectus). The ninth, tenth, eleventh, and twelfth nerves are but rarely involved.
Intra-cerebellar tumours seldom give rise to pressure effects on isolated cranial nerves. On the other hand, one expects ipso-lateral paresis or paralysis, with exaggerated reflexes (see [Fig. 78]). Conjugate deviation of the eyes to the side opposite to that on which the tumour is placed is a fairly frequent symptom, the deviation being associated with well-marked lateral nystagmus. When the tumour is of considerable size, or placed nearer the central portion of the cerebellum, pressure may be exerted on the pyramidal fibres with paresis or paralysis on the contra-lateral side of the body.
In addition, allusion should be made to Dana’s symptom—‘cerebellar fits’—said to be almost pathognomonic of an extra-cerebellar tumour (or abscess) situated in the cerebello-pontine angle. In such cases, there may be sudden attacks of tinnitus, vertigo, and apparent loss of consciousness, during which the patient falls to the ground as if struck with lightning. The final stage of falling is said to be dependent, not so much on actual loss of consciousness, as from the absence of cerebellar innervation and a total loss of equilibrium. These attacks are brought about by sudden alterations in position.
(G) To the pituitary region.
Considerable research has recently been carried out, and much knowledge obtained as to the functions of the pituitary body and the symptoms that result from lesions of the gland.[44] As is well known, the pituitary body consists of two portions, an anterior (derived from upgrowth of buccal epiblast) and a posterior (formed from neural epiblastic downgrowth).
Complete removal of the body in animals invariably terminates fatally, the patient exhibiting a definite train of symptoms—cachexia hypophyseopriva—and dying within a few days or weeks, the younger animals living longer than the older. The symptoms of apituitarism are as follows: fall of body temperature, lowering of blood-pressure, increasing feebleness, muscular tremors, a curious attitude resembling that of defæcation, coma, and death.
On further investigation it was proved that all these symptoms were observed when the anterior portion of the gland was alone removed, whilst, on the other hand, extirpation of the posterior half created no great change in the animal’s general health.
Fig. 70. A Pituitary Tumour.
In the human being it would appear that the symptoms resulting from the development of pituitary tumour formation may be classified into two groups, those of hyper-pituitarism and those of hypo-pituitarism.
In the former case the secretion being superabundant, acromegaly and giantism are observed. Keith[45] considers that one of the substances secreted by the gland is of the nature of a hormone, rendering the osteoblasts hypersensitive to the various stresses that fall upon the human skeleton during life, and that the osteoblasts, at the origins and insertions of muscles, become increasingly sensitive to the traction of muscles. Muscular impressions and processes of the skeleton become exaggerated by the new bony matter, and if the epiphyseal lines be still open, the osteoblasts of which appear to be specially affected, giantism is produced. The skull and skeleton of the giant O’Brien are regarded as typical examples of the results due to over-secretion of the gland.
Hypo-pituitarism leads to a striking and rapid development of fat (adiposity), loss of sexual power and amenorrhœa, persistence of sexual infantilism (if the patient be attacked when young), harsh skin and œdematous tissues, subnormal temperature, and psychic disturbances.
In any case, whether the secretion of the gland be increased or decreased, the developing tumour tends to compress those cranial nerves with which it is in close anatomical relation. For instance, the gland, being situated immediately behind the optic chiasma, tends to compress the mesial nasal optic fibres producing bilateral temporal hemianopia, with primary optic atrophy as a final result. In some cases optic neuritis is observed with secondary atrophy. The third, fourth, and sixth nerves may also be affected, with consequent squints, ptosis, and perhaps complete ophthalmoplegia.
In addition, it should be noted that glycosuria and albuminuria have been observed.
In the general diagnosis of brain tumours, reference must be made to Lumbar puncture and X-ray investigation.
Lumbar puncture.
With respect to the desirability of carrying out lumbar puncture in brain tumours and the value of the information obtained, considerable difference of opinion exists. Lumbar puncture supplies information as to the tension of cerebro-spinal fluid and as to its bacteriological and cytological character. The evidence so obtained as to tension is of little value in view of the proved increase of intracranial pressure as evidenced by the mental condition of the patient, the headache, optic neuritis, &c. On the other hand, bacteriological and cytological examination of the fluid may point to the tuberculous or syphilitic composition of the tumour, thus offering help from the point of view of treatment. Still, information of almost equal importance can be obtained by tuberculin, Wassermann, and other tests. There is also considerable risk attendant on the process. The rapid withdrawal of cerebro-spinal fluid has been followed by disastrous results, the medullary stem being suddenly forced downwards into the foramen magnum, with corking up of that aperture, and complete upset of the medullary centres. Such a disaster is the more likely to occur when the tumour is subtentorial in position. Looking at the question from the broadest point of view, it would appear that the performance of lumbar puncture in cases of suspected brain tumour is fraught with considerable peril.
X-ray examination.
X-ray examination should always be carried out. More commonly the results are negative, the nature of the tumour seldom permitting sufficient shadow formation. Occasionally the firmer and denser tumours allow of a more definite result. When the tumour arises from the bone, or is so situated as to change the shape of the part with which it is in contact, valuable information will be obtained. For example, the hollowing out and general enlargement of the sella turcica in pituitary tumour formation.
Treatment.
Indications for operation.
The indications for operation must be considered under two groups:—
Those for radical operation aiming at the removal of the tumour.
Those for palliative operation aiming at the alleviation of symptoms.
For the radical operation.
According to Risien Russell,[46] the following are the main indications:—
(1) Cases in which the tumour can be accurately diagnosed.
(2) Cases in which the tumour is situated in an accessible position. The more favourable sites are the surface of the cerebrum, the lateral lobe of the cerebellum, and the cerebello-pontine angle.
(3) Cases in which there is reason to believe that the tumour is simple, and of such a nature that it can be removed from its bed.
(4) Cases in which there is reason to believe that the removal of the tumour will not greatly imperil the patient’s life, and, furthermore, will not result secondarily in the development of fits, paralysis, aphasia, &c.
For the palliative operation.
The following are the main indications for operation:—
To prolong life.
To alleviate the severe and persistent headache.
To stop fits.
To save the sight.
And, in general, to benefit the patient by reducing the increased intracranial pressure, even though it may be quite impossible to remove or even locate the tumour.
Of all the considerations enumerated above, for which palliative measures are indicated, there is no symptom which more urgently demands alleviation than optic neuritis. This question of sight-saving may be accepted as a basis on which to estimate the value of palliative measures in general. It is obvious that no mere ‘decompression’ operation will save the sight when the optic inflammation has progressed to atrophy, and even in the earlier conditions of neuritis cases must be carefully chosen. Herbert Bruce[47] admirably clinches the matter in the following words: ‘As to the prediction of improvement of vision after trephining, everything depends on the condition of the disks. Yellowish white patches of exudate or white atrophic changes, especially when associated with macular changes, all indicate that the secondary changes in the disks will be permanent. In proportion to this development will the vision be impaired, whilst when the loss of vision has been dependent on the swelling of the disks, then not only will the sight be saved but largely improved. In other words, one might say, therefore, that when the neuritis has not progressed on to atrophy the sight would be saved.’ Even in the event, however, of the ocular conditions being unfavourable for palliative operation, other factors in the case still remain—the terrible and persistent headache, the fits, the emaciation from vomiting, &c., all of which require the most careful consideration, and all of which can be remedied by an efficient decompression operation.
Radical operation for cerebral tumours.
After the usual preparatory treatment and the application of the scalp-tourniquet, the skull is opened either by craniectomy or craniotomy. The two methods—with their relative advantages and disadvantages—have already been described (see [Chapter II]), but there can be no question that a brain tumour should be exposed by the formation of an osteoplastic flap. Such a procedure is called for on the ground that the exact localization of the tumour is always a matter of very great difficulty, and that it is impossible to foretell with certainty as to whether it will be feasible to remove the tumour or not.
Fig. 71a. First Stage in the Formation of an Osteoplastic Flap. Gigli’s saw, protected from the dura mater by the special director, passing between the two trephine holes. For further description, see text.
Fig. 71b. Second Stage in the Formation of an Osteoplastic Flap. The bone-flap turned down and the dura mater exposed.
Fig. 71c. Third Stage in the Formation of an Osteoplastic Flap. The dural flap turned down and the brain exposed. Note the relation of the scalp, bone, and dural incisions to one another.
A bone-flap is framed suited to the occasion, and permitting adequate exposure of the dura. The question then arises as to whether the dura should be incised, the brain explored, and an attempt made at the removal of the tumour, or whether these procedures should be postponed till the patient shall have recovered from any shock attendant on the first stage. The two-stage operation—first advocated by Horsley—is insisted on by some surgeons. By others it is maintained that it is preferable to complete the operation at one sitting, mainly on the ground that two anæsthetics and two operations are more dangerous than one. As to which course should be adopted is entirely dependent on the general condition of the patient at the termination of the bone-flap formation. If his condition is quite satisfactory, if there has been but little hæmorrhage, and if the blood-pressure shows no tendency to drop, then it is perfectly justifiable to ‘carry on’, opening the dura mater and searching for the tumour. Still, as the shock entailed during the first stage may be considerable, as the surgeon cannot possibly foresee with certainty what lies beneath the dura mater, and as considerable time must elapse, and some hæmorrhage result during the further procedures required for the reflection of the dura mater and removal of the tumour, it follows that it is generally advisable to conduct the operation in two stages, the second operation being carried out some days later. Not less than five to seven days should elapse between stage one and stage two, the scalp-flap is then but lightly healed, whilst all blood-vessels should be sealed. The patient also will have entirely recovered from any shock attendant on the first stage.
At the second stage, the dura may be more or less covered with a film of coagulated blood, meningeal arteries and the outline of venous sinuses being correspondingly obscured. Consequently, if the dural flap proposed for the second operation should include these structures, the meningeal vessels may be ligatured and the sinuses mapped out with guide-threads at the completion of the first stage.
Examination of the dura mater.
Considerable help may be obtained by examination of the dura mater, both with regard to the localization of the tumour and investigation as to its nature. Pulsation may be abolished or diminished, whilst the tenseness of the membrane is increased in direct proportion to the size and site of the tumour. The membrane also may be œdematous or adherent, anæmic in colour from pressure exercised by an underlying tumour, reddened from vascularization, grey-brown from the immediate presence of a malignant mass, plum-coloured from the adjacency of a subdural hæmorrhage, opaque from the presence of an arachnoid cyst.
Some evidence as to the nature of the tumour may be obtained by palpation—fluctuation suggesting cyst formation, solidity pointing to more definite formation.
Opening the dura mater.
The membrane can be opened either by crucial incision or by flap formation. The latter method is to be preferred. All meningeal vessels that cross the line proposed for dural section must be underrun on either side of that line. The dural incision should always fall short of the margins of the gap in the skull by at least 1⁄2 inch, in order to allow of accurate approximation at the termination of the operation.
The following points with respect to the opening of the dura mater, though already enumerated in [Chapter II], should be noted. The membrane is lightly incised with the scalpel, and, so soon as the pia-arachnoid is exposed, the section completed with the blunt-pointed scissors, or on a grooved director. The dural flap is then turned down and the brain laid bare. It is most essential that every precaution should be taken to avoid injury to superficial cerebral veins—the cortex is probably under high tension, firmly compressed against the dura mater and bulging out forcibly so soon as tension is relieved.
Examination of the brain.
In the event of the exposure of the tumour, its removal can at once be attempted. If, however, the tumour be subcortical in position, its position and boundaries may be estimated by electrical stimulation, palpation and exploration.
Electrical stimulation will evidence whether the area exposed corresponds to the symptoms evinced by the patient. With respect to the actual technique, one pole is placed on the patient’s extremity—it matters not which, though preferably on the homo-lateral side—the other over the exposed brain. The current should be just strong enough to contract exposed muscle—some of the fibres of the temporal muscle are generally available for the purpose. If there is much pia-arachnoid œdema, some of the fluid should be evacuated—by gentle scratching of the membranes—and the bare brain stimulated. In the event of complete degeneration of the pyramidal tracts there is little or no response to such stimulation. Under other circumstances the results are quite definite.
Palpation may reveal the nature of the tumour, whether fluid or solid.
Exploration of the brain should only be undertaken in the light of a reasonably certain diagnosis, and every precaution must be taken to avoid needless damage to the cerebral substance. The exploration should invariably be preceded by incision with the brain-knife or scalpel, introduced in such a manner as to avoid injury to all visible vessels and directed at right angles to the surface of the brain, so as to cause the least possible damage to the corona radiata, &c.
Extirpation of the tumour.
The proportion of brain tumours surgically removable is small, and even when the tumour is fully exposed considerable experience is required in estimating the possibility of removal.
When the tumour is circumscribed, whether meningeal, cortical, or subcortical, it may be shelled out of its bed with greater or lesser ease according to its nature and position. This shelling out process is carried out with an ordinary tea-spoon or scoop. Hæmorrhage may be severe though generally readily controlled by lightly packing with dry gauze. More rarely one or more of the superficial vessels will require to be underrun with a small needle threaded with the finest catgut. Muscle grafts (see [p. 18]) may be of considerable assistance.
If a cyst be found it may be possible to shell it out entire, failing which the parietal wall is freely dissected away, and the cavity drained for two or three days.
Fig. 72. Combined Flap Formation and Decompression. After osteoplastic resection, the tumour has been found irremovable. The dura mater is therefore sewn back in position, after which a portion of the bone is nibbled away from the bone-flap—as depicted in the illustration—and the underlying dura mater freely incised.
If the tumour be extensive and ill-defined in margin, no attempt should be made at removal, the surgeon remaining content with the second desideratum of brain tumours in general—the production of a general decrease of intracranial pressure. This might be readily effected by leaving the dura open and by removing at the same time the osseous portion of the osteoplastic flap. The bone is readily dissected away and free decompression would be permitted. In such cases, however, the hernial protrusion is usually excessive, and insomuch as an osteoplastic flap is more often than not framed over the Rolandic region, the protrusion would include the motor area with disastrous results on the contra-lateral extremities. This course, therefore, should never be adopted. In such cases it is infinitely preferable to follow Cushing’s method of combined exploration and decompression. This is done as follows: ‘From under the portion of temporal muscle which has been turned back with the flap, a roughly semicircular area of bone is cut away with heavy rongeurs, which remove bone without jar, and so without risk of stripping the remainder of the resected bone from the soft parts. This accomplished, a similar area is rongeured away from the side of the skull well down the temporal fossa under the tourniquet, the temporal muscle being held away by a retractor. If the base of the bone has been made sufficiently broad, a margin possibly a centimetre in width can be left on each side as a support for the flap after its replacement. A subtemporal bone defect is thus secured with even less difficulty than is experienced in making the usual subtemporal opening from without through a split muscle incision. The dura is then carefully opened and incised in a stellate fashion to the margin of what promises to be a sufficient circle of denuded cortex for a generous decompression.’
Closure of the dura and reposition of the flap.
Whether the tumour has been exposed and removed, is deemed irremovable, or has not been found, the dural flap should be approximated and carefully sutured in position. In many cases, however, this dural approximation is exceedingly difficult to accomplish, by reason of the outward bulging of the diseased or œdematous brain. This difficulty may be overcome by adopting one or more of the following methods:—
Elevation of the head, thus reducing the amount of blood in the brain.
Lumbar puncture, a method that presents some danger when the surgeon has to deal with a subtentorial tumour, but which bears in its train excellent results from the point of view of reduction of intracranial pressure. The danger arises from the fact that the sudden escape of cerebro-spinal fluid may cause the brain-stem to be engaged in the foramen magnum, with disastrous results on the medullary centres.
Ventricular puncture, when the ventricles are dilated. A blunt-pointed aspirating needle is introduced into the lateral ventricle through the most prominent portion of the exposed brain, and a sufficient quantity of cerebro-spinal fluid evacuated.
‘Milking’ the pia-arachnoid, the pia-arachnoid being pricked with a needle in several places and the contained fluid squeezed out.
Subtemporal decompression—the final resource. When all other measures fail, a subtemporal decompression may be conducted on the opposite side of the brain.
The dura should be accurately sutured with numerous interrupted silk sutures. It is very important that every precaution should be taken to prevent the continued escape of cerebro-spinal fluid, and, for this and other obvious reasons, it is necessary to avoid drainage whenever possible. If such a course should be necessary—by reason of hæmorrhage—a cigarette drain may be brought out at the most dependent and convenient angle of the dural flap, and through one of the trephine holes or gap purposely cut in the bone-flap.
In any case, the bone-flap is replaced, resting on its shelf and anchored by means of numerous deep sutures, each of which picks up the aponeurosis or muscle both along the upper border of the flap and the two downward vertical prolongations. These sutures will also control bleeding from the divided scalp-vessels. The tourniquet is removed, dressings applied, and the whole maintained firmly in position by a gauze bandage applied circumferentially. These dressings are supported by bandages and the patient sent back to bed.
If the tumour has been exposed by craniectomy, the gap in the skull will probably require protection. This procedure (see [Chapter VI]) can be carried out at the termination of the main operation or at a later date. This latter course is to be preferred.
Radical operation for cerebellar tumours.
Craniectomy may be regarded as the operation of choice in the exposure and removal of cerebellar tumours. The formation of an osteoplastic flap is contra-indicated (see [p. 29]). The operative procedures vary according as to whether it is desired to expose the one or both cerebellar hemispheres. Bilateral exposure, though presenting the great advantage of offering a larger field for exploration, is by far the more serious of the two operations.
Unilateral cerebellar exposure.
The patient being placed in the semi-prone or face-down position, the incision starts at the posterior border of the apex of the mastoid process, curves inwards along the superior curved line of the occipital bone to the occipital protuberance, and then passes straight down the middle line of the neck for 2 to 3 inches. If the incision is deepened at once to the bone, hæmorrhage is severe. The incision should first involve the skin and then the muscles attached to the occipital bone. Each vessel as encountered is clipped and tied. The flap must be turned down right up to the posterior margin of the foramen magnum.
The flap being held aside, the pin of the trephine is placed in such a manner that the disk to be removed will correspond to the thin central portion of the cerebellar fossa. The trephine, placed low down, is directed more or less towards the anterior fontanelle.
The disk being removed, the bone is freely cut away with rongeur forceps—outwards to the posterior border of the mastoid process, upwards to the curved line, inwards to near the middle line, and downwards to the posterior margin of the foramen magnum.
This generally completes the first stage of the operation, for, in cerebellar tumours, it is usually advisable to complete the operation in two stages. The scalp-flap is replaced, lightly sewn into position, and the patient sent back to bed.
A few days later the flap is again turned down, the dura incised, and turned down as a flap the convexity of which corresponds to but falls short of the line of the lateral sinus. The cerebellar substance is then examined and the tumour removed after the lines enumerated in dealing with cerebral tumours. Greater difficulty, however, is experienced in the attempted removal of cerebellar tumours, for the operator is working in a very confined space, and because the cerebellum tends to herniate through the adventitious hole in dura and bone. Two other factors must be taken into consideration: (1) the danger incident to all cerebellar operations of respiratory failure,[48] and (2) the friability of the cerebellar substance. Every care must be taken to avoid unnecessary damage of the brain-matter.
When the tumour is situated in the cerebello-pontine angle, a somewhat favourite site for tumour formation, ‘lateral displacement’ of the cerebellum towards the middle line will aid considerably in the exposure. A flat retractor, bent to a suitable curve, is introduced between the dura and the cerebellum, and the brain-matter gently but firmly retracted towards the middle line. As the brain yields to the pressure the tip of the retractor is insinuated towards the posterior surface of the petrous bone. With the aid of a head-lamp a good view may usually be obtained of the region involved, and, as the tumour is but lightly attached, its removal can be undertaken.
The dura is then carefully sutured and the scalp-flap accurately replaced, deep sutures for the muscles and a few surface sutures for the skin. Drainage should be avoided whenever possible—the discharge of cerebro-spinal fluid is fraught with considerable danger. The gap in the skull requires no other protection than that afforded by the mass of neck muscles.
Fig. 73a. Unilateral Exposure of the Left Half of the Cerebellum by Craniectomy. The scalp-flap has been turned down and is fully retracted. The cerebellum has been exposed by means of a crescentic dural flap.
Fig. 73b. Bilateral Exposure of the Cerebellum by Craniectomy. The left half of the cerebellum has been exposed. The trephine is being applied over the right cerebellar region. Note the position of the trephine and the direction in which it is being applied.
Fig. 73c. Bilateral Exposure of the Cerebellum by Craniectomy. The walls of both cerebellar fossæ have been cut away, exposing the bulging dura mater. The Gigli saw is in position for removal of the bridge of bone intervening between the two cerebellar fossæ.
Fig. 73d. Bilateral Exposure of the Cerebellum by Craniectomy. The bridge of bone has been removed, two crescentic flaps of dura mater have been turned down, and the falx cerebelli has been ligatured in two places and divided.
Bilateral cerebellar exposure.
This operation is also done in two stages. In the first, each cerebellar fossa is exposed in turn, the scalp-flap being framed and the trephining and cutting away of the bone carried out in the manner previously described for unilateral exposure. The osseous bridge which separates the two openings in the skull is divided above and below with Gigli’s saw, and the intermediate part removed. This completes stage one.
In the second stage, again carried out a few days later, two dural flaps are turned down, each similar to the one described in unilateral exposure. This leaves a central portion of dura, that part which encloses the occipital sinus and to which the falx cerebelli is attached. By means of an aneurysm needle, threaded with catgut, passed through or around the falx, the occipital sinus is ligatured above and below, the ligatures being applied as high and as low as circumstances permit. The falx is then divided between the two ligatures and the two flaps thrown upwards and downwards respectively.
The extra space so afforded not only allows of the exposure of both hemispheres, but also permits of the further dislocation of the one lobe towards the opposite side, thus facilitating the examination of the lateral aspect of the cerebellum and of the cerebello-pontine angle.
This bilateral method is a serious operation. Hæmorrhage may be severe, and the attendant risks of respiratory failure are not inconsiderable. It should only be adopted (1) when a tumour is so situated or so extensive that more space is required than supplied by unilateral exposure, and (2) when bilateral cerebello-pontine tumours are suspected.
Palliative operations for cerebral and cerebellar tumours.
A primary palliative operation may be conducted over the region of the tumour itself, in the cerebellar region, or over the temporal lobe—one of the so-called ‘silent’ areas of the brain.
It is obvious that the greatest degree of pressure relief will be obtained by craniectomy conducted over the region of the tumour itself. To this course, however, there are two great objections: (1) the exposed cortex most commonly includes the motor area, herniation of which will lead to disastrous effects on the extremities of the contra-lateral side—spasticity, paralysis, aphasia, &c.; and (2) the herniation of brain-matter including, or closely related to, an irremovable tumour tends to lead to œdema of the brain tissues and softening of and hæmorrhage into the growth, with subsequent rapid development of the outwardly protruded mass.
With respect to cerebellar decompression operations, I must confess that I have formed a most unfavourable opinion. The subtentorial pressure can undoubtedly be relieved most effectually by such methods, but the immediate results are not infrequently disastrous, the patient dying within a few days as a result of the complete upset of medullary centres.
In the event of the surgeon deciding to confine his attempts to palliative treatment—alleviation of symptoms only—the subtemporal operation of Cushing is certainly the method of choice. The technique of the operation and its general advantages have already been discussed. It merely remains to add that, when the operation is conducted for tumour relief and not for injury as discussed in [Chapter IV], no attempt is made to explore the temporo-sphenoidal lobe and drainage is contra-indicated. The dura, widely incised, is left open, the temporal muscle and fascia accurately sutured, and the scalp-flap secured with fine silk sutures.
With regard to the side on which this subtemporal decompression operation is to be conducted, the best results are obtained by operating on that side on which the tumour is situated. In the event of doubt, the right side is chosen, so avoiding any possibility of including, in the hernial protrusion, the motor speech area of Broca. The cranial defect should be made as large as possible, and in the event of failure in bringing about adequate decompression, a similar operation is conducted at a later date on the opposite side of the skull.
After subtemporal decompression there should be no mortality.
The immediate results are eminently satisfactory—headache is relieved, optic neuritis steadily diminishes, vomiting ceases, and the general condition of the patient is immensely improved.
The expectancy of life after such decompression operations requires careful consideration. So much depends on the nature of the tumour that it is difficult to make more than a general observation. In many cases life has been prolonged for one to two years, whilst instances are recorded in which the patient has lived for five to six years—not in a miserable condition as might be imagined, but in comparative comfort.
It might be added that, as the tumour grows, a one-sided subtemporal decompression may gradually become insufficient. In such cases, recrudescence of symptoms—redevelopment of optic neuritis, &c.—may be met by further decompression on the opposite side of the head.
Operations for tumours of the pituitary body.
The pituitary body may be approached by the frontal, temporal, and nasal routes. The temporal route, advocated by Caton and Paul[49] and Horsley, possesses the disadvantage that the surgeon, whilst utilizing an approach similar to that used in the Hartley-Krause operation for trigeminal neuralgia, encounters on his way the structures laterally situated to the pituitary body, the internal carotid, the cavernous sinus, the third, fourth, and sixth nerves, and the ophthalmic division of the fifth. The anatomical difficulties are therefore considerable. Added to this, the tumour, in its hollowing out of the central portion of the sella turcica, may leave such lateral osseous walls that an approach from the side is impossible.
The frontal route is strongly advocated by Krause.[50] He states that, ‘an osteoplastic flap is framed in the frontal region, immediately to one side of the middle line, so as to avoid the superior longitudinal sinus and frontal air sinus, and turned upwards. It is essential that the operator should approach the tumour along the floor of the anterior fossa, and, for this purpose, it may be deemed necessary to chip away the bone in the region of the supra-orbital ridge. Some days later, the final stages of the operation are conducted. The dura mater covering the frontal lobe is stripped away from the bone and traction applied to the dura by means of broad flat spatulæ. When the lesser wing of the sphenoid is exposed, the dura mater is opened in the vertical direction on a line with the lower median angle of the wound at a depth of 5 to 51⁄2 centimetres, as measured from the anterior surface of the frontal bone. If the incision is made at a deeper point there is danger of injury to the optic nerve, which is covered with dura mater in this situation. Laterally the dura is opened parallel to the posterior border of the lesser wing of the sphenoid, about 1⁄2 cm. in front of it, to avoid the sinus which lies immediately in contact with the edge of the bone. This exposes the optic nerve, coming from the chiasma and the internal carotid. The pituitary body is located beneath the anterior edge of the chiasma. The diaphragm of the sella turcica is now carefully incised with a small hook-shaped scalpel, and the hypophysis is readily removed.’
The nasal route, advocated by Bruns and successfully carried out by Schloffer[51] and Cushing, seems to offer the greatest advantages and give the most successful results. The general details of the operation are as follows: starting either beneath the upper lip or externally at the base of the septum, the mucous membrane is peeled away from each side of the vomer, and, by gradual piecemeal removal of that bone, the advance is carried out towards the base of the skull in what may be called an intra-mucous space. By the introduction of suitable instruments into this space the cavity is gradually enlarged, at the expense of the turbinated bones which are compressed by the dilating instruments. By this means—gradual removal of the septum—the operator approaches the base of the skull, always working between the two layers of mucous membrane, and always avoiding, with the greatest care, any laceration of the same. Laceration at once converts the more or less aseptic operation into an infected one. When the base of the skull is laid bare in the region of the sphenoidal sinus, the bone is there chiselled away and the under surface of the pituitary body exposed. It can then be removed piecemeal.
The general details of the operation as enumerated above may require amendment as our knowledge increases. Sufficient has been said, however, to point out the various methods of approach and the advantages claimed for the nasal route.
Results of operation on brain tumours.
Statistics are always fallacious, and this is especially the case with regard to operations on tumours of the brain. Few surgeons have operated on a sufficient number of cases to compile satisfactory statistical tables. These tables are generally made up from the combined experience of many operators, all using their own methods. The following, however, will serve to give an approximate idea as to mortality, &c.
Mortality.
From earlier records the immediate mortality was estimated at 30-40 per cent. Duret, however, records 400 cases with a mortality of 19·5 per cent., 58 cases dying from shock, 10 from hyperpyrexia, and 10 from hæmorrhage. In my own practice, the mortality may be estimated at a much lower figure. Perhaps I may be too conservative, but I hold the view that, unless the tumour is readily exposed and equally readily removable, it is inadvisable to carry out further measures for its eradication. Moreover, the general technique of brain surgery has advanced with rapid strides, and the question of early and accurate localization has received equal attention. The mortality has diminished proportionately, and may be estimated at less than 20 per cent. So much depends on the surgeon and on the nature of the tumour, its position and localization, that it is impossible to make any absolute statement as to the risk to life attendant on operation. If all tumours were fibromata, cortically situated, and accurately diagnosed, the operation, in the hands of a skilled neurological surgeon, should present but a very low mortality. So long, however, as surgeons will persist in burrowing into the brain substance for a supposed subcortical tumour, so long will the mortality remain high. The great secret in operating on a brain tumour lies in knowing when to terminate the attempt at removal of the tumour and when to rest content with a pure ‘decompression’.
It is obvious, therefore, that cortical tumours—more especially such as give rise to early localizing symptoms, e.g. Rolandic tumours—offer a better prognosis than when the surgeon has to deal with subcortical, central, and basal tumour formation.
The mortality according to the region affected.
The following table, from a series collected by Knapp, supplies valuable information as to the regional mortality.
| Frontal | tumours | 32 | cases | Mortality, | 25 | per cent. |
| Central | „ | 231 | „ | „ | 23 | „ |
| Parietal | „ | 29 | „ | „ | 41 | „ |
| Temporal | „ | 17 | „ | „ | 29 | „ |
| Occipital | „ | 10 | „ | „ | 20 | „ |
| Cerebellar | „ | 54 | „ | „ | 45 | „ |
Sir Victor Horsley draws attention to this question in the following manner: ‘If a line be drawn from the frontal eminences to the occipital protuberance, it is obvious that more shock results from operations below that line than from above, and as we proceed from the frontal to the cerebellar pole of the encephalon.’
The mortality according as to whether the tumour is found or not.
According to Horsley, of 79 cases in which a correct diagnosis was made and the tumour removed, 7 died from shock; whilst in 16 cases inaccurately diagnosed, 6 died—a mortality of 9 per cent. in the first case as against 37 per cent. in the second.
The added danger resulting from unsuccessful attempts at finding the tumour must not be advanced as an argument against the palliative operations, for the failure to find and remove the tumour implies diligent search for the neoplasm, with necessary prolongation of operative procedures, and perhaps extensive manipulation of the brain substance. Statistics and experience both afford conclusive evidence that accurate localization is essential for the success of the operation.
[39] Paton, Brain, vol. xxxiii, p. 67.
[40] Pyschische Störungen bei Hirntumor, 1903.
[41] Lettsomian Lectures, by the late Dr. Charles Beevor; Duret, Tumours of the Brain; Nothnagel, Tumours of the Brain, &c.
[42] Brit. Med. Journal, March 1, 1908.
[43] Lancet, July 10, 1909.
[44] Crowe, Cushing, and Homans, Johns Hopkins Bulletin, May 1910.
[45] Lancet, April 15, 1904.
[46] Brit. Med. Journal, October 26, 1906.
[47] Annals of Surgery, 1907, p. 543.
[48] In the event of cessation of respiration during trephining, the skull should be opened and the dura incised with the utmost expedition. The relief of tension so afforded often allows of respiratory recovery—with or without artificial respiration.
[49] Brit. Med. Journ., 1893, p. 1421.
[50] Surgery of the Brain, vol. i, p. 117.
[51] Wien. klin. Wochensch., No. 21, 1907.