HYDROCEPHALUS
The conditions that lead up to internal hydrocephalus are classified by Parkes Weber[13] in the following manner:—
1. ‘Cases secondary to and part of the phenomena of tuberculous or any suppurative meningitis, comparable to pleural effusions due to tuberculous or any septic invasions of the pleura.
2. Cases resulting from the presence of tumours, &c., analogous to the pleuritic effusions accompanying tumours, &c., situated close to or involving the pleura.
3. Ordinary infantile or congenital hydrocephalus, which is, in some cases at least, due to intra-uterine meningitis.
4. Internal hydrocephalus supervening on the epidemic or sporadic type of posterior basic non-suppurative meningitis.
6. Simple idiopathic internal hydrocephalus of adults or older children due to serous ependymitis or ventricular meningitis.
7. Traumatic cases.’
This classification possibly includes all the various grades and degrees of internal hydrocephalus, but for all practical purposes the cases may be grouped into two classes, congenital and acquired, both of which may be either acute or chronic.
Congenital internal hydrocephalus.
The condition may be recognized soon after the birth of the child, or the enlargement of the head may only become apparent some weeks or months later. The slow development and the insidious nature of the enlargement, as observed in many cases, may lead to some confusion between the late congenital and the early acquired varieties. However, the absence of any symptoms pointing to meningeal inflammation between the time of the birth of the child and the hydrocephalic development usually allows of correct classification.
It is doubtful whether congenital internal hydrocephalus can be ascribed to malformation of the inter-ventricular channels and occlusion of the passages by means of which the cerebro-spinal fluid escapes into the cerebral subarachnoid space, or whether the development is dependent on hypersecretion from the ependyma and choroid plexuses. Virchow showed that occasionally there was an actual formation of small grey-red masses, about the size of a hemp-seed or cherry, in the walls of the ventricles, but other authorities deny the existence of such changes, and consider that the hydrocephalic condition is entirely dependent on congenital malformation.
It would, however, seem more probable that we have to deal with two distinct varieties of congenital internal hydrocephalus, one resulting from intra-uterine ependymal inflammation (? syphilitic), the other dependent on congenital malformations, especially in the region of the fourth ventricle, where the foramina of Majendie, Key, and Retzius are regarded as permitting the outward escape of the fluid secreted from the lining membrane and choroid plexuses of the ventricles.
Acquired hydrocephalus.
Acquired hydrocephalus, whether acute or chronic, presents certain antecedents or associations which enable us to have a more clear idea as to the pathological conditions present.
In the majority of cases it is secondary to basic meningitis which, whether tuberculous or not, results in matting of membranes and in the development of adhesions. The normal flow of cerebro-spinal fluid from the ventricular to the cerebral subarachnoid spaces is thus impeded.
Similar interference to the flow of cerebro-spinal fluid may be caused by the growth of a tumour, especially those which originate in the subtentorial region.
Progress of the case.
Whether the progress of the case be acute or chronic, the ultimate results are much the same. The fluid in the ventricular spaces may be increased up to 1,000 c.c. or more, pressure effects being exerted on the surrounding parts, with the following results:—
A. The soft cerebral substance is slowly but surely compressed, with the result that the sulci on the surface of the brain are more or less obliterated, distinction between the white and grey matter may be lost, the ventricular spaces are enormously dilated, and, in the most marked cases, a mere shell of brain may intervene between the ventricles and the surface of the brain.
This cerebral compression results in the development of two main groups of symptoms, those referable to the general increase in the intraventricular pressure and those due to regional compression.
The more general results are headache, vomiting, optic neuritis and atrophy, slow pulse-rate, somnolence, and coma. The temperature is variable, more commonly rising during the more acute stages of the disease, and falling to normal or subnormal during the quiescent periods.
Localizing features are to be found in squints, inequality of pupils, retraction of the head and neck, dyspnœa, and dysphagia, whilst compression of the cortical motor centres is evidenced by twitchings, convulsions, and spasticity of the limbs. General convulsions are by no means uncommon. Remissions and intermissions of both local and general symptoms are frequently observed, paralyses, for example, fluctuating in depth and character.
B. The bones comprising the vault of the skull become greatly thinned and widely separated from one another, the fontanelles enlarged, and the sutures unduly prominent. The head becomes enlarged in all directions, and its increased weight renders the child incapable of retaining postural control, the head being top-heavy and falling about in all directions.
The bones of the base share in the deformity. The pressure exerted on the orbital plates of the frontal bone force the globe in the downward direction in such a manner that the infra-corneal sclerotic is obscured by the lower lid, whilst the supra-corneal portion is unduly prominent. The bony eminences in the region of the sella turcica are diminished in size, the middle fossa of the skull flattened from side to side, and the posterior fossa from before backwards. In such cases the skull assumes an almost dolicocephalic appearance. In any case, the disproportion between the enlarged skull and diminutive face is a marked feature.[14]
The scalp becomes stretched, hairs are sparse and brittle, and the veins dilated.
Treatment.
Indications for operation.
The results obtained by operation for internal hydrocephalus are not sufficiently encouraging to enable the surgeon to urge immediate operative treatment.[15] Still, it is perfectly clear that he cannot possibly carry out surgical treatment with benefit to the patient if the ventricular distension is allowed to progress to such a degree that marked cortical flattening and degeneration occurs. No fixed probationary period can be laid down as a guide, each case must be judged on its own merits. Special attention should be paid, however, to the disks and lower extremities. Any suggestion of optic neuritis or spasticity should be regarded as urgently demanding operative interference.
Lumbar puncture
cannot be expected to confer other than temporary benefit even under the most favourable circumstances, whilst, in the event of interference in the normal communication between the ventricular and cerebro-spinal spaces, no relief can be anticipated. Connal recommends that lumbar puncture should be carried out daily, or twice daily, over extended periods of time. This operation, however, is by no means devoid of danger, and the results obtained by such treatment are not at all satisfactory.
Operation.
Operations are carried out (a) with the object of withdrawing fluid from the distended ventricular cavities (ventricular puncture), and (b) to establish a communication, or short-circuit, between the ventricular space and other spaces (ventricular drainage).
Ventricular puncture.
This operation may be carried out through the anterior fontanelle, through the frontal bone, or over the descending cornu of the lateral ventricle.
Through the anterior fontanelle.
The region of the fontanelle is shaved and cleansed in the usual manner, after which the surrounding parts are cut off from the field of operation by a large sheet of gauze or lint, in which a hole is cut sufficing to allow of exposure of the site of election for puncture.
The patient should be in the recumbent position, the head well towards the end of the table. The operation is performed without an anæsthetic or under local anæsthesia. A site is chosen at the outer angle of the fontanelle, about 1 inch away from the median antero-posterior line, thus avoiding all possibility of injuring the superior longitudinal venous sinus. The trocar and cannula, of small size, is passed directly inwards, towards the base of the skull, for a distance of not more than 2 inches. The trocar is withdrawn and the fluid allowed to escape slowly. If the cerebro-spinal fluid escapes at high pressure, the flow should be regulated by the finger placed over the mouth of the cannula, and, in any case, it is inadvisable to allow of the withdrawal of more than 50 c.c. (approximately 11⁄2 ounces) at one sitting. The cannula is withdrawn and the site of tapping covered with collodion gauze. Even when adopting all precautions the operation is not without danger, and, added to this, is the fact that few surgeons care about introducing an instrument blindly into the cerebral cortex—the risk of puncturing one of the distended superficial cerebral veins is sufficiently obvious.
Through the frontal bone.
Tillmanns, in recommending this procedure, states that ‘the needle should be inserted about 2 centimetres from the central line and 3 centimetres from the precentral sulcus. You strike the ventricle at a depth of from 3 to 5 centimetres’. He claims that this method leads to satisfactory results. It is open, however, to all the objections of puncture through the fontanelle.
Over the descending cornu of the lateral ventricle.
This operation is strongly recommended by Keen on the ground that excellent drainage is supplied. A point is mapped out on the skull which lies 11⁄4 inches behind the external auditory meatus and the same distance above Reid’s base-line. If the postero-lateral fontanelle be open a small trocar and cannula may be introduced at the upper angle of the space—thus avoiding the lateral sinus—and passed inwards in a direction towards the summit of the opposite ear. If the fontanelle be closed, a scalp-flap is framed and a bone-disk removed with a 1⁄4-1⁄2 inch diameter trephine. The dura should not be opened. The evacuating instrument is then introduced through the membrane in the same direction as before. In either case it should not be passed for a greater distance than 11⁄2 inches, and, in all cases, the exploration should be of a progressive nature, that is to say, the trocar should be withdrawn once for each 1⁄2 inch of brain substance perforated. The escape of cerebro-spinal fluid must be regulated in the manner previously described.
If trephining has been necessitated, the bone-disk is not replaced, thus allowing of subsequent tappings through the trephine-hole, this gap now taking the place of a patent postero-lateral fontanelle.
Keen’s method of ventricular puncture presents many advantages over other methods, though still open to the objection that the actual central puncture is done blindly.
Ventricular-subdural drainage.
A point is mapped out on the scalp which corresponds to the surface-marking of the descending horn of the lateral ventricle (see [p. 3]), and, with this point as a guide, a scalp-flap is framed, the base of which lies immediately below the indicated spot whilst its convexity is situated between 11⁄2 and 2 inches above. This flap should not include the pericranium. The flap is turned down to its base, the pericranium stripped aside and a disk of bone removed, at the upper part of the exposed bone, with a 1⁄4 or 1⁄2 inch diameter trephine. The bone is usually very thin.
A
B
Fig. 26. Diagrammatic Representation of the Author’s Operation for Hydrocephalus Internus. A. The osteoplastic exposure of the brain (A, The bone; B, Upper two-thirds of trephine hole; C, Dura mater; D, The four dural flaps; E, Site of brain perforation; F, The brain; G, Line of fracture of bone-flap; H, The bone-flap; I, The Scalp; J, Lower third of trephine hole). B. Ventriculo-subdural drainage (s., The scalp; b., The bone; d., The dura mater; v., The lateral ventricle; t., The drainage medium between the ventricular cavity and the subdural space; s.l.s., Superior longitudinal sinus; f.c., Falx cerebri).
When this disk is removed, the dura is separated from the bone, and, with the aid of a strong pair of scissors, the bone is cut in such a manner as to form a bone-flap, the margins of which lie well within those of the scalp-flap (see [Fig. 26]). This flap is broken across at its base, turned down, and covered with gauze.
At the lower portion of the exposed dura mater, a crucial incision is made through the dura mater and a blunt-pointed trocar and cannula introduced at the centre of the exposed brain, all visible vessels being avoided. The diagnosis is now confirmed—by the withdrawal of the trocar and the escape of cerebro-spinal fluid.
Fig. 27. The Conversion of Hydrocephalus internus into Cephalocele.
By the introduction of a bundle of horsehair or catgut, passed through the cannula so as to project into the ventricular cavity, and, after the withdrawal of the cannula, tucked, with respect to the proximal ends, into the subdural, extra-dural, or subaponeurotic spaces, it is obvious that drainage may be established between the ventricles and the other regions. Experience showed, however, that drainage into the subaponeurotic space usually converted the condition of hydrocephalus into one of cephalocele (see [Fig. 27]), the fluid collecting as a localized fluid tumour over the region of exploration, whilst extra-dural drains did not permit of sufficiently rapid reabsorption of fluid. Subdural drainage gave the best results, the cerebro-spinal fluid being brought into relation with the pia-arachnoid meshwork of vessels. It would, of course, be infinitely preferable if the ventricular fluid could be brought into direct relation with the veins of the subarachnoid space, for the cerebro-spinal tension and venous pressure are equal, and all excess of cerebro-spinal fluid would be absorbed as soon as it is formed. This course is, however, impossible to carry out. We have, therefore, to rest content with less direct contact, drainage into the subdural space. This ventricular-subdural drainage, as obtained by horsehair, catgut, and silk, apparently leads to but temporary benefit, probably owing to falling together of the brain substance and obliteration of the adventitious passage.
Silver tubes and bone tubes have been utilized, but the results are sometimes disappointing. In one of my recent cases the two halves of a bone tube were utilized. The tube was cut across in an oblique manner at about its centre, the two parts set at right angles to one another and sewn together with silk. One arm is introduced into the ventricle, the other tucked underneath the dura mater. The child improved considerably, but the method is not altogether satisfactory and by no means easy of application. In another case I utilized strands of silver wire. The depth of brain-tissue necessary to reach the ventricular cavity was measured, and two or three strands of wire introduced so as to project well into that space, then steadied with forceps whilst the proximal ends were bent at right angles to the surface of the brain and tucked underneath the dura mater. The method was unsatisfactory.
Tubular drainage is not essential, for the fluid escapes from the ventricle as much alongside the tube as through its lumen. Still, I believe that tubular drainage is preferable to other methods, and, realizing the difficulty of introducing a right-angled tube—one arm to project into the ventricle, the other to lie beneath the dura mater—Messrs. Arnold & Son are now making for me small and light right-angled silver tubes so constructed that each limb can be inserted independently, after which they can be locked together. This method appears to overcome many of the difficulties previously encountered. The tube is inserted after the formation of the osteoplastic flap, as described above. The four dural flaps are then united, preferably by cross union of their apices, the bone-flap is replaced, and the scalp-flap sewn accurately into position. Collodion gauze, applied to the wound, aids in the prevention of cerebro-spinal escape.
The scalp and bone-flaps are framed, and the dural incision carried out low down, so as to make the opening to the brain as valvular as possible. All these precautions are taken to avoid leakage of cerebro-spinal fluid, a most troublesome complication—adding to the risk of infection and often resulting in an acute eczematous condition of the surrounding skin.
By this method it is hoped that a permanent fistulous communication will be formed between the lateral ventricle and the subdural space.
Ventriculo-abdominal drainage.
The following method of drainage has been devised by Cushing: ‘It having been established that the ventricle can be emptied by the lumbar route, and that the withdrawal of fluid is not prejudicial to the child’s well-being, the following procedure is carried out. A laparotomy is performed; the posterior layer of peritoneum to the left of the rectum is split; the body of the fifth lumbar vertebra, just under the bifurcation of the vessels is exposed; the bone is trephined and one-half (the female portion) of a silver cannula, exactly the size of the trephine, is inserted and held in position. The child is then turned on his face and a laminectomy performed; the subarachnoid space is opened, the strands of the cauda separated, and the posterior half (male portion) of the cannula is invaginated, so that it locks into the portion inserted anteriorly. Both wounds are then closed. The fluid for a time finds its way into the peritoneal cavity, but ultimately into the retro-peritoneal space whence it is taken up by the receptaculum chyli, as experimental observations have shown.’
Cushing has carried out this operation in 12 cases with a considerable degree of success.
Recently, another method of treatment has been carried out by Cotterill.[16] A large semilunar flap is made from the occipital region, exposing the bone. Trephine circles are made on either side of the median ridge, and the intermediate part of the bone, together with the posterior part of the foramen magnum, is removed. The dura mater is opened and the occipital sinus ligatured. The lateral lobes of the cerebellum are then held apart, and the thickened arachnoid over the posterior part of these lobes and over the roof of the fourth ventricle exposed. This roof is opened. The wound is then closed.
By this method drainage from the ventricle is said to be reestablished. Though without personal experience of this extensive procedure, one cannot avoid expressing considerable doubt as to its advisability.
My own experience would lead me to the following conclusions:—
1. Whilst recognizing that internal hydrocephalus usually demands surgical interference, it is only in some few cases that material benefit results. Some recent successful cases point to the possibility of better results in the future.
2. The operation which promises the best results, combined with the least risk to the patient’s life, is that described as ventriculo-subdural drainage.
[ [4] Der Hirnbruch und seine Behandlung. Moscow, 1896.
[ [5] De la céphalhydrocèle traumatique (Travaux de Neur. Chir., iii. 1898).
[ [6] Archives Italiennes de Biologie, vol. xxxviii, p. 444.
[ [7] Der Hirnbruch und seine Behandlung. Moscow, 1896.
[ [8] Beitr. zur klin. Chir., vol. iii, p. 228.
[ [9] St. Bart. Hosp. Reports. Lawrence Ward. May 5, 1896.
[10] Beitr. zur klin. Chir., vol. vii, p. 228.
[11] American Practice of Surgery. Bryant and Buck.
[12] Tumours, Innocent and Malignant. Bland Sutton.
[13] Brain, 1902, p. 140.
[14] In estimating the size of the head, the following tables—after Bonnifay—will be useful:—
| Age. | Circumference of head (average). | ||
|---|---|---|---|
| Birth to fifteenth day | 343 | millimetres | (approximate). |
| Fifteenth day to 2 months | 368 | „ | „ |
| At 3 months | 388 | „ | „ |
| Six months to 1 year | 429 | „ | „ |
| One year to 2 years | 459 | „ | „ |
| Normal rapidity of growth of the head | |||
|---|---|---|---|
| During the first 3 months | 44 | millimetres | (approximate). |
| During 3 to 6 months | 41 | „ | „ |
| From 6 months to 1 year | 30 | „ | „ |
| During second year | 14 | „ | „ |
It should be noted that enlargement of the head can only take place during the years previous to synostosis of the skull bones. Leonard Guthrie (Harveian Lecture, March 17, 1910) writes, ‘I cannot find from any recorded cases of hydrocephalus acquired in later childhood and adult life that an increase in the size of the head has been any aid to diagnosis, and I believe it is true that internal hydrocephalus acquired after the sutures are set is hardly distinguishable from a non-localizable intracranial new growth giving rise to headache, vomiting, and optic neuritis.’
[15] The treatment for acquired hydrocephalus dependent on tumour formation is discussed elsewhere. This section deals with the congenital variety and with those cases of acquired hydrocephalus not due to obstruction by tumours.
[16] Review of Neurology and Psychiatry, vol. ix, No. 1, p. 1.
CHAPTER IV
FRACTURES OF THE SKULL
General considerations.
Fractures of the skull do not form more than one-twentieth part of the fractures admitted annually into the hospitals, but, in spite of this relative infrequency of occurrence, the difficulties attendant on diagnosis, the numerous associated complications, and the all-important question of treatment, invest this subject with a special interest.
The whole question of skull fractures is beset with difficulties, many of which, it is hoped, will be swept away in this and subsequent chapters.
Brief allusion must first be made to some important points in connexion with the anatomical structure of the skull, such as bear relation to fractures and aid in the appreciation of the extent and mechanism of the fracture.
The vault varies in density to a remarkable degree, not only in its several parts, but also in different individuals. Cases have now and again been recorded in which a very trivial blow, totally insufficient to produce any definite osseous lesion in the normal individual, has resulted in the production of a vault or basic fracture. Each case, therefore, must be judged on its own merits.
The vault derives its strength from its shape and structure. The two tables are of equal strength, and, for the most part, separated from one another by a variable amount of diploic tissue. This diploe is most abundant in the frontal, parietal, and upper occipital regions. These parts are proportionately strong. Two regions are practically devoid of this inter-tabular buffer—the squamo-temporal and cerebellar (see [Figs. 29] and [30]). A recognition of this comparative weakness is of great practical importance in view of the fact that both these regions are liable to special lesions—injury to the middle meningeal artery in the first case, and, in the second, cerebello-medullary lesions. Nature’s ‘mistake’ in providing coverings unsuited to requirements has been compensated for in part by additional protection—the temporal and nuchal muscles.
Fig. 28. Diagram illustrating the Lines along which Forces received on the Vault are transmitted to the Base. (For further description, see text.)
Further, not only does the skull vary in density in its several parts, but it is also ribbed and strengthened by various bony bars and buttresses that pass up from base to vault (see [Fig. 28]). These ‘ribbings’ are seen to extend upwards from the crista galli, from the external angular frontal process, from the auditory region, and from the occipital protuberance. Presumably, these ‘ribbings’ were so constituted for a definite purpose; in any case, it is clear that they play an important part in the reception and conduction of forces to the base of the skull. It is apparent, moreover, that the parts intervening between these ‘ribbings’ are liable to injury in direct proportion to their general position and strength. The deep groovings of the bone for the reception of the middle meningeal artery afford an additional source of weakness to the bone in the squamo-temporal region. (See [Fig. 50]).
Fig. 29 a. The Base of the Skull.
Fig. 29 b. The Base of the Skull as seen on Transillumination.
Further reference will be made to the relative strengths of the various regions of the skull. Sufficient has been said to show that nature has provided the skull with various paths by means of which forces applied to the vault can be conducted and distributed to the base.
Before, however, proceeding to discuss the effects produced on the base of the skull, it is necessary to add that nature provides other methods by means of which the intensity of a blow, delivered over the vertex of the skull, is diminished. The forces are broken up and distributed in the following manner:—
1. Though the force tends to travel in the direction of the applied force, yet the convexity of the skull allows of the dissemination of that force over a large superficial area.
2. The intervention of cartilage or fibrous tissue between two or more of the component bones of the vault tends to diminish the intensity of the force, to break it up and to alter its direction.
3. The bony ridges, along which the forces tend to travel, themselves terminate blindly (see [Fig. 28]). Thus,
(a) Forces passing from the frontal region converge, more or less, to the crista galli.
(b) Forces from the external angular frontal process pass along the wings of the sphenoid bone to the anterior clinoid process.
(c) Forces from the auditory region are projected along the summit of the petrous bone towards the apex of that process and to the posterior clinoid process.
(d) Forces applied to the occipital region travel inwards along the internal occipital crest to the strengthened margins of the foramen magnum, or are projected outwards along the lateral sinus ridges. In the former case, the force either passes forwards towards the dorsum ephipii and so again reaches the posterior clinoid process, or is directed more laterally towards the jugular process of the occipital bone, there meeting the fibrous tissue intervening between that process and the corresponding part of the temporal bone.
4. All forces, whether transmitted along the internal occipital crest, the temporal bone, the sphenoidal wings, or the crista galli of the ethmoid, are further transmitted to the dura mater attached to those prominences and ridges. The dura mater undoubtedly plays an important part in the reception and transmission of the forces.
5. The forces all show a tendency to converge towards the pituitary region, the great ‘water-cushion’ of the brain—a region bounded by the clinoid processes. That these processes receive a considerable part of the forces transmitted is confirmed by the fact that they are frequently torn away from their basic attachments. This is especially the case with respect to the attenuated base of the anterior clinoid process.
It is obvious, therefore, that forces tend to be transmitted from the vault to the base, and yet the base is, in many respects, the weakest part of the skull. It is perforated by numerous foramina, it is hollowed out in places for the formation of air sinuses and for the reception of the integral portions of the auditory apparatus. Furthermore, it presents a more or less plane surface, one differing in all respects from the marked convexity of the vault. Those forces, therefore, which are received by the base of the skull are not subjected to that diffusion which forms so conspicuous a feature in the case of the vault.
All these points tend to show that the base of the skull is more or less unsuited for the reception of severe blows, direct or transmitted, whilst, on the other hand, nature has taken into consideration and provided fairly adequately against the dangers incident to vault injuries.
It is not proposed at this stage to discuss further the relative strength of vault and base. Points, other than those already enumerated, will be brought forward in subsequent sections.