276 Affections oculaires Reflexes, Paris, 1866.
TABES DORSALIS.—That affections of the eye are common in this grave malady is admitted by all writers, but as to their frequency and nature at the different stages of the disease, there is wide diversity of opinion: this is probably in part due to the fact that from the chronic nature of the disease, which extends usually over a period of several years, it is rare that the case remains from beginning to end under care of the same observer. The symptoms are of three varieties—viz. firstly, transient paralyses of the external muscles of the eye; secondly, changes in the iris and ciliary body; and, thirdly, affections of the optic nerve. The first-named symptoms are frequent in the early stages of the disease. Sometimes they affect the external muscles supplied by the third pair, and at others the rectus externus. Their transient character and frequency, while admitted by all observers, have as yet received no adequate explanation, it being indeed difficult to see why transient affections of the motor nerves should be so common in a disease which has its seat in the posterior sensory columns of the spinal cord, and which presents such formidable and irreparable lesions. The pupillary symptoms are, as a rule, those of myosis, sometimes mydriasis, and at times the so-called Argyll-Robertson symptom (viz. a moderate myosis, with diminished reaction to light, but prompt response to convergence and accommodation). The last symptom is by no means present in all cases and at all stages of the complaint; but where it exists there is a remarkable resistance to the action of mydriatics. Trousseau was probably the first to call attention to this state of affairs. The writer has repeatedly seen cases where a strong solution of sulphate of atropia failed to produce any more than one-third of the usual dilatation produced by the same amount of the drug. Trousseau and Duchenne have both observed that during attacks of violent pain the pupils of ataxic patients will sometimes undergo temporary dilatation. Atrophy of the optic nerve (either partial or complete) is a frequent, and often an early, symptom of tabes dorsalis, and even may precede by many years the development of spinal symptoms. Foerster relates a case where complete optic atrophy preceded the development of all other symptoms by a period of three years, he having seen a number of other instances when atrophy preceded the other symptoms for a less period. Charcot records a case where the interval was ten years, and states that sooner or later locomotor ataxia develops in the majority of cases of optic atrophy in his wards in the Salpêtrière. Gowers gives two interesting cases, in one of which blindness came on fifteen years before the development of the other symptoms, the interval in the second being twenty years. Buzzard277 also has recorded an observation where blindness and lightning pains manifested themselves fifteen years before the development of the other ataxic symptoms. If we were to estimate the frequency of optic atrophy as a symptom of early development of tabes dorsalis by the cases seen at ophthalmic hospitals, we should probably much overrate its proportion, inasmuch as those cases in which atrophy is a more marked and early symptom alone resort to such places. Leber found that 13 (26 per cent.) out of 87 cases at his clinic had spinal symptoms, while Gowers gives 20 per cent. as a relation existing between degeneration of the optic nerves and tabes. The latter author thinks that the ratio should really be stated as 15 per cent., because 5 per cent. was due to cases which had been sent to him for examination by his colleagues. Nettleship classifies 76 cases of optic atrophy as follows: 38 as presenting undoubted symptoms of locomotor ataxia; 11 as showing mixed spinal and cerebral symptoms (as in general paralysis of the insane); 9 with other forms of spinal degeneration without brain lesions, these associated with reflex iridoplegia without other symptoms of spinal or cerebral disease; and 15 only in which there was no manifest disorder of other parts of the nervous system. In the earlier stages of degeneration of the optic nerve in tabes dorsalis the discs are usually of a dull reddish-gray tint, and, while they are still capillary superficially, their deeper layers next to the lamina cribrosa have a decidedly diminished blood-circulation, and appear of a marked and more neutral gray color. The surface of the discs often looks more or less fluffy, there being enough haze of the retinal fibres to veil, and at times to hide, the scleral ring. Later, the superficial capillarity disappears and the discs assume a pallid, filled-in aspect, being surrounded by a scleral ring which is everywhere too broad: at this stage the main stems of the retinal arteries and veins exhibit no marked change in calibre, but later on we find them shrinking, and the surface of the disc becomes excavated, the nerve itself often assuming a greenish tint. The earlier stages of such degenerations often exist for a long time, and are demonstrable by the ophthalmoscope before the sight is sufficiently impaired to prevent the patient from executing any ordinary work; this being dependent upon the facts that at first there is only a concentric diminution of the field for form and colors, while central vision remains for a long time unaffected. According to Foerster, this contraction of the field commences at the outer part. In advanced cases there are often irregular sector-like defects. This state of affairs makes it probable that while the number of cases in which total blindness precedes the development of tabetic symptoms is probably rated much too high, from the natural gathering of such cases at ophthalmic hospitals, yet, nevertheless, the frequency of incomplete gray degeneration of the optic nerves in the early stages of the complaint is probably, as a rule, much underrated.
277 Brain, ii. 1878, p. 168.
Foerster has most justly called attention to the remarkable mental cheerfulness of persons laboring under this malady, and states that he has frequently seen cases where the patients would insist that they were improving, while examination of the acuity and of the field of vision showed steady failure of the eyesight. The writer's personal experience has on several occasions substantiated this statement. According to Cyon,278 tabes presents three varieties: First, tabes dorsalis. This variety commences with paralyses of the eye-muscles and amblyopia. The pupils are not contracted. The amblyopia progresses. Cramp-like disturbances of innervation are always present, with a want of co-ordination of movements and anæsthesia of the upper extremities, while mental disturbances are often demonstrable. Second, tabes cervicalis. Myosis, with intense boring pains in the extremities and impotence, are its chief characteristics. Ataxia is rare, and disturbances of vision develop only late in the course of the disease. Third, a class which he considers the true form of tabes dorsalis, in which there are marked anæsthesia, formication, bladder and rectal symptoms, associated with motor disturbances which often end in paralysis. In such cases there are no eye symptoms except occasional dilatation of the pupil. The same writer has collected 203 cases reported by various authors, and gives the following tables as showing the relative frequency of eye symptoms:
| Amblyopia | 33 times. |
| Paralysis of eye-muscles | 30 times. |
| Mydriasis | 3 times. |
| Myosis | 9 times. |
| 75 times. | |
| Amaurosis with affections of eye-muscles | 16 times. |
| Amaurosis with mydriasis | 8 times. |
| Amaurosis with myosis | 1 time. |
| Affections of the eye-muscles with mydriasis | 4 times. |
| Amaurosis with mydriasis and affection of the eye-muscles | 2 times. |
He remarks279 that the number of reported cases of mydriasis is probably excessive, and says that dilatation has been improperly noted, as, for instance, where one pupil is normal and the other contracted. As regards the frequency of the Argyll-Robertson symptoms, Vincent280 found it present in 40 cases out of 51, in which there were 7 cases of amaurosis with immobile pupils, 5 being marked exceptions to the rule. Out of 51 cases of tabes, the same author found myosis in 27. The statements of Vincent (as will be seen) differ materially from those of Cyon. Erb281 found that in 56 cases, there were only 7 in which the optic nerves were affected (12½ per cent.), while in 17 there were affections of the eye-muscles (30.3 per cent.). He considers myosis a frequent symptom, but thinks that the stage at which it develops is not yet determined. The anatomical cause of the want of sensitiveness of the pupils to light, while they retain their movements of convergence and accommodation, has not been well made out. Vincent282 attributes it to a paralysis of the excito-motor filaments which supply the iris, and which he locates at the upper portion of the spine; while Wernicke thinks it due to degeneration of the filaments which go from the third pair to the optic nerve. Hughlings-Jackson283 tells us that the pupils which fail to react to light often act but slightly with convergence, and in a note gives two cases of absolutely immobile pupils where the accommodation was nearly normal for the age. In fact, much remains to be accomplished in the study of the innervation of the iris and ciliary muscle in tabes. The proportion of cases in which cycloplegia occurs, and what relation it bears in point of time and frequency to the presence of iridoplegia, are far from being well made out. Jackson also insists that tabes does not necessarily follow in all cases of long-standing optic atrophy. On a basis of 72 cases Gowers says that some formal ophthalmoplegia interna was present in 92 per cent. He groups these cases into three stages: No. 1, where there is loss of knee-jerks, lightning pains, difficulty of standing with toes out and heels together, there being a want of ataxic gait; 2, where there is an ataxic gait, but the patient can still walk by the aid of a stick; 3, where the patient cannot walk without the assistance of another person. In 23 of his cases in the first stage (84 per cent.) symptoms of palsy of some of the intraocular muscles were found; in the second stage, 29 cases (93 per cent.); in the third stage, 18 cases (100 per cent.). Erb has called attention to the fact that reflex dilatation of the pupil from sharp stimulation of the skin of the temple is usually absent where we have the Argyll-Robertson pupil. Gowers admits that this is the rule, but has seen several cases where, although there was no attempt at myosis on exposure to light, yet there was marked dilatation on stimulating the skin.
278 Tabes Dorsalis Berlin, 1866, p. 43.
279 Loc. cit., p. 71.
280 Thèse de Paris, cited by Robin, p. 20.
281 Nagel's Jahresbericht der Ophthalmologie, 1872, p. 150.