Chapter XLVII: Introduction: The object of the following essay is to give, as far as (3)

Yellow Fever.--In this disease most writers have called attention to the accompanying ocular symptoms--flushing and injection of the conjunctiva with increase of lachrymation, followed later by a change of the color of this membrane to a yellow hue, which precedes a similar change of the color of the skin of the face and other parts of the body. The first epidemic of the disease in Philadelphia occurred in 1762. Redman,[157] in describing it, says: "The patients were generally seized with a sudden and severe pain in the head and eyeballs, which were, I think, often, though not always, a little inflamed or had a reddish cast." Another severe epidemic of the disease visited the city in 1793, of which Rush[158] has given us a valuable account. Among the premonitory signs he enumerated "a dull-watery-brilliant, yellow or red eye, dim and imperfect vision;" and he defines his meaning by saying that the dull eye was found among the severe cases, and the brilliant one where the poison was less intense. Later in the disease there was "preternatural dilatation of the pupil," and in one case "a squinting which marks a high degree of morbid affection of the brain." There were hemorrhages, chiefly from the nose and uterus, and in but one case "a dropping of blood from the inner canthus." A dimness of sight was very common in the beginning of the disease, and many were affected with temporary blindness. In some there was a loss of sight in consequence of gutta serena or a total destruction of the substance of the eye. The eyes seldom escaped the yellow tinge. There were a number of cases of uncommon malignity without this symptom, but sometimes the yellow color appeared on the neck and breast before it invaded the eyes. Wood,[159] who witnessed a later epidemic (also in Philadelphia), says that even in the earliest period of the disease the white of the eye is often reddened and turbid, and in bad cases appears sometimes as if bloodshot. As before stated, in the course of the disease {768} this redness yields to a yellow or orange color. Féraud,[160] in speaking of the symptoms of the second stage, lays great stress on the brilliancy of the eyes, their lachrymose condition, the fulness and nicety of the conjunctival injection, the dilatation of the pupil, and the presence of photophobia; adding that this congestion is diminished during the remission of the fever if the attack is not severe, but that if the conjunctiva darkens and assumes an icteric aspect, which becomes more and more intense, the case is undoubtedly severe. He adds that ocular hemorrhages occur in some grave cases during the second stage, producing subconjunctival suffusion and a flow of blood from the neighborhood of the commissure of the lids. Such "hemorrhages have frequently caused conjunctivitis, keratitis, and even such an accident as phlegmon." Fernandez[161] gives three cases of delirium, suppression of urine, and loss of vision. One of these cases was examined with the ophthalmoscope, but no changes were found in the eye-ground. One case recovered, having entirely regained his eyesight; the other two died.

[Footnote 157: "An Account of the Yellow Fever of 1762," by John Redman, M.D. (read before the College of Physicians of Philadelphia, Sept. 7, 1793).]

[Footnote 158: _An Account of the Bilious Remitting Yellow Fever as it appeared in the City of Philadelphia in the Year 1793_, by Benjamin Rush, M.D., Philada., 1794.]

[Footnote 159: G. B. Wood, _Treatise on the Practice of Medicine_, vol. i. p. 321, 1858.]

[Footnote 160: Béranger-Féraud, "La Fièvre jaune à la Martinique," quoted by Juan Santos Fernandez, _Archiv. of Ophthalmology_, x., 4, 1881, pp. 440-445.]

[Footnote 161: _Loc. cit._]

Intermittent Fever.--Intermittent ophthalmia is but rarely encountered in countries where only a mild form of intermittent fever is present; in fact, it was so rare in Scotland that Mackenzie in the earlier editions of his work denied its existence, but a larger experience enabled him (in 1854) to give three cases. In 1828 and 1829 it was so infrequent in Marburg that Hueter devoted two papers to its study--one of a case of the quotidian type, and the second of the septan form of the ophthalmia. In countries where the malarial poison exists in more intense form, we have quite a different state of affairs; thus Levrier[162] describes it as of common occurrence in the district of Landes in France, and says that its most frequent form is a periorbital and ocular neuralgia, accompanied by intense congestion of the conjunctiva, with increased flow of tears and a greater or less degree of photophobia, occurring in those who have had frequent attacks of intermittent fever. Wehle, whose observations were made in Hungary, describes an erysipelatous swelling of the lids with small hemorrhages in the palpebral conjunctiva, redness and swelling of the bulbar conjunctiva with intense photophobia, and occasional clouding of the cornea. Arlt[163] relates eight cases of chronic interstitial keratitis, all occurring in emaciated patients who had had severe malarial fevers, in Slavonia and Hungary. Only three of these stayed for prolonged treatment, which consisted of the use of Karlsbad water, followed by the preparations of quinine and iron; all of these recovered, and their eyes cleared, leaving only the faintest trace of corneal opacity. Galezowski[164] gives a case of malarial keratitis, and Griesinger,[165] after describing the usual symptoms of the disease (similar to that noted by Levrier), speaks of cases of long duration accompanied by clouding of the cornea and atrophy of the eyeball. He has also encountered an intermittent form of iritis. Mackenzie describes a case of it (one of those above referred to) which eventually ended in amaurosis. While affections of the retina and optic {769} nerve from malarial fever would seem to be rare in temperate latitudes, Guéneau de Mussy,[166] however, relates a case of optic perineuritis with retinal apoplexies. Macnamara, observing in India, says the serous retinitis is not uncommon in malarial fever, and that in severe cases of this disease amaurosis is not infrequent. Galezowski and Kohn each reports a case of atrophy of the optic nerves after a severe attack of intermittent fever, but it is not quite evident from the clinical history whether the blindness might not be attributed to the large doses of sulphate of quinia which had been administered.

[Footnote 162: J. F. Levrier, _Thèse de Paris_, 1879, "Des Accidents oculaires dans les Fièvres intermittentes," p. 56.]

[Footnote 163: _Klinische Darstellung der Krankheiten des Auges_, 1881, pp. 121, 122.]

[Footnote 164: Quoted by Levrier, _loc. cit._, p. 39.]

[Footnote 165: _Traité des Maladies infectueuses_.]

[Footnote 166: _Journal d'Ophthalmologie_, p. 1, 1872.]

ERYSIPELAS.--Erysipelas of the face and head frequently causes swelling of the lids and chemosis of the bulbar conjunctiva, and occasionally gives rise to an orbital cellulitis which by its effects on the optic nerve impairs or destroys sight. Beer[167] speaks of an idiopathic erysipelatous conjunctivitis which may not be accompanied by swelling of the lids. The conjunctiva is of a pale, somewhat livid-red hue, in which no distinct vessels are visible, there being numerous bright-red ecchymotic spots in the subconjunctival tissue. Vesicular prominences form around the cornea, and become so large as to project between the lids. The folds and interstices of this swollen membrane are covered with thin mucus, which often adheres so closely to the cornea as to make it look hazy, but which can be washed off, leaving the corneal surface as brilliant as in its normal state. The conjunctival swelling finally subsides, and the membrane again adheres to the sclerotic. Even after there is apparent absorption of the ecchymoses, the places where there were extravasations of blood are slow in adhering to the sclera, and often roll into folds with every motion of the eye. Mackenzie describes the conjunctiva as of a pale yellowish-red color: it rises in soft vesicles around the cornea, and these change in shape with every motion of the eye. There is slight photophobia and a pricking sensation, with a large quantity of white mucus, which is secreted by the conjunctiva and the Meibomian glands. Where a low grade of orbital cellulitis ensues we may have only slight prominence of the eye and some interference with its motions, in which a complete subsidence of the symptoms without any failure of eyesight may take place. We may encounter more severe cases, where the intense swelling and inflammation of the orbital tissues so impair the functions of the optic nerve and retina as to permanently destroy the eyesight, and at times destroy life by the extension of the inflammation to the meninges. The cellulitis may attack one or both orbits. Poland[168] has recorded a case of protrusion of both eyes where, after death, the ophthalmic veins and the cavernous sinuses were found full of pus; while Cohn[169] has reported another fatal case of double erysipelatous cellulitis, in which post-mortem showed purulent phlebitis of the orbit and brain with embolic infarcta in the lungs. All cases of double exophthalmos from erysipelas do not end as fatally: Jaeger has recorded two cases of recovery, where in each one eye remained permanently blind, while the other was restored to sight. He has given us accurate and beautiful ophthalmoscopic plates of the {770} lesions in the blind eyes, these plates showing atrophy of the optic nerve, with great thickening of walls of the retinal vessels, which in some places totally hide their contents, while in others the blood-columns are still faintly visible. In one case the inflammation of the lids had been so severe that they had grown together in the middle of the palpebral fissure and had also formed an attachment to the eyeball. These cicatricial bands were divided with the knife, only to find a blind eye with dilated pupil. In one of Jaeger's cases there were pigment-masses in the choroid. Coggin[170] describes a case of double exophthalmos with blindness where the corneæ were so denuded of epithelium that no ophthalmoscopic examination was practicable. Three weeks later the media were clear and the discs atrophic, the vessels being visible as empty white cords. These effects be attributed to thrombosis. Knapp[171] has recorded a most interesting case of erysipelas where there was severe fever with high temperature (104.8°) and marked protrusion of both eyes, in which he had an opportunity of observing the eye-grounds in all stages of the disease. On the ninth day ophthalmoscopic examination showed that the yellow spot and disc were both invisible, and that their localities could only be determined by the radiation of the tortuous veins, which were gorged with blood so dark as almost to be black, the retinal arteries being invisible. The posterior portion of the eye-ground was milky white, while the anterior was reddish white: numerous hemorrhages were scattered through the retina, more or less linear in shape in the posterior part and irregularly rounded in the anterior portion. Two days later the orbital swelling was less, and the arteries were visible, though much reduced in size, and the eye-ground was beginning to resume its normal color. About a month after seizure the patient was convalescent and he could go out. At this time the disc was atrophic, and there was a whitish cloud in the region of the yellow spot, with numerous hemorrhages: both arteries and veins presented isolated areas of perivasculitis, accompanied by snow-white patches of greater or less extent, which were of the same calibre as the adjacent dark-red blood-columns in each of them. Two months later, the disc was still atrophic, the hemorrhages had been absorbed, the blood-vessels were mostly visible as white cords--one of them presenting the usual appearance, while two showed blood-contents for a short distance surrounded by dense white walls. The white intercalary portions of the vessels seen in the examination two months after the onset of the disease are considered by Knapp to be thrombi. Arlt, Jr., reports a case of gangrenous erysipelas of the lids with loss of the eye, and mentions that his father had seen several similar cases.

[Footnote 167: J. J. Beer, _Lehre von den Augenkrankheiten_, vol. i. 398, 399. (He also gives a colored plate of the appearance, Taf. 1, p. 3.)]

[Footnote 168: _R. L. O. H. Rep._, vol. i., pp. 26-31, 1857.]

[Footnote 169: _Klinik der Embolischen Gefärskrankheiten_, 1860, p. 196.]

[Footnote 170: D. Coggin, _Trans. Amer. Oph. Soc._, vol. ii. pp. 570-572 (session 1878).]

[Footnote 171: _Trans. Amer. Oph. Soc._, 1883, and _Arch. of Ophthalmology_, 1884 (with plates and lithographs).]

* * * * *

{771} DISEASES OF THE NERVOUS SYSTEM.[172]

[Footnote 172: In the foregoing sections the relationship between definite diseases and their concomitant eye symptoms have been dealt with; whereas in this division of the subject this has been found so impracticable that it had to be discarded in favor of an anatomical basis upon which to place the various affections. This change has necessitated the disuse of the representative headings of names of disease, and the substitution of absolute physical conditions with their hypothetical causes.]

Symptoms of impaired function in the eyes and their appendages have always been regarded as valuable indices of disease of the nervous system; and when it is considered that six of the twelve pairs of cranial nerves send branches to these organs, and that the second, third, fourth, and sixth pairs are distributed exclusively to them, and that they are further supplied with twigs from the cervical and cerebral sympathetic nerves, it can be readily appreciated that a vast variety of nerve lesions, interfering with some of these connections either at their origins or in their course, may produce either impaired vision in the eye or loss of power in some of its appendages. Moreover, the retina and optic nerve originate as sprouts from the anterior cerebral vesicle, and retain respectively the structure of a ganglion and of a cerebral commissure. From these circumstances, as well as from the close connection of their blood and lymph circulations with those of the cerebrum, they frequently become delicate exponents of intracranial changes.

Affections of the Second Pair (Nervi Optici).

NEURITIS.--Five years after the discovery of the ophthalmoscope Graefe called attention to the fact that in many cases of intracranial disease the intraocular ends of the optic nerve presented marked changes. He had already discovered that when these changes were inflammatory in character they presented two main varieties--the one in which there was intense swelling of the intraocular end of the nerve (designated by him stasis papilla); and the other, in which there was a dull-red suffusion of the disc. In the first variety, which he attributed to increased intracranial pressure from tumor or other cause, the disc projected into the eye and formed a small tumor, often prominent to an extent equal to its own diameter, the oedematous and opaque nerve-fibre being permeated by tortuous, enlarged, and often newly-formed capillary vessels, which hide the arteries and allow only the projecting branches or lips of the tortuous and dilated retinal veins to be perceived as they slope down in the swollen papilla to regain their normal level in the retina; the other, which he thought was due to meningitis spreading along the nerve, was characterized by a slightly swollen disc of a dull-red color, with opacity of its nerve-fibre sufficient to completely hide its normal boundaries, associated with tortuous veins and arteries that were often diminished in size. Since that time volumes have been written on the subject, and it has given rise to most extended and searching discussion, causing researches to be instituted which have added much to the knowledge of the anatomy and pathology of the central connections, circulation, and lymph-supply of the optic nerves. To-day the first variety is usually designated {772} as choked disc or papillitis, and the second as interstitial or descending neuritis. When typical cases are seen at the height of the disease, it is easy to make a distinction between the two varieties, but usually they shade off so imperceptibly, the one into the other, and the consecutive atrophies present so absolutely the same appearance, that no experienced observer would at all times claim an ability to distinguish between them. In the choked disc the intense swelling is limited to the intraocular end of the nerve, and therefore vision is little interfered with until the swelling becomes so great, or the contraction of the subsequent cicatrization so decided, that by pressure on the nerve-fibre they become atrophic and incapable of reporting the retinal image to the brain-centres, while in interstitial neuritis, owing to the primary interference with conduction, vision is impaired from the beginning. The choked disc usually develops slowly, requiring a period varying from a few days to two, three, or four weeks to attain its maximum, and it may exist unchanged for a long time before atrophy sets in. The writer once had an opportunity of observing a case in which the choking was produced by a cerebral gumma, and where for nearly a year the discs remained swollen and vision was still 6/8; and another of intense swelling, where the discs projected at least from one and a half dioptrics (one millimeter), in which for a period of three months vision was 6/6 and the field almost normal. Mauthner,[173] Blessig, and Schiess-Gemuseus[174] each record cases of marked choking of the discs lasting for some time, where the patients retained perfect central vision to the day of their death. Double choked discs are almost always a symptom of grave intracranial disease when all local causes in the eyes or orbits have been excluded. Even in the very exceptional cases where they form part of the symptoms of Bright's disease they are probably indicative of intracranial effusion. The lower grades of inflammation of the optic nerve are apt to be accompanied by marked proliferation of the connective tissue between the nerve-bundles. There are many cases of congestive atrophic change of the optic nerve where at first central vision is but little affected. In judging of the appearance of neuritis the observer should be sufficiently familiar with the changes in the eye-grounds of healthy individuals which occur from local causes not to allow himself to be led astray by the often very decided neuro-retinitis constantly encountered in hard-worked eyes with uncorrected astigmatism and slight degrees of ametropia; and not to mistake these changes, which are simply an expression of that local congestion which leads ultimately to softening and elongation of the eyeballs, for changes due to incipient cerebral disease, although each is accompanied by neuralgia. While, after careful study of the various forms of neuritis optici during the last few years, it is acknowledged that increased intracranial pressure is apt to cause choking of the disc, and that basilar meningitis frequently gives rise to interstitial neuritis, we are still far from having such a clear comprehension of the subject as to render the profession unanimous as regards its pathology; some observers claiming that choked disc is essentially a vaso-motor paralysis of the affected part, while others maintain that it is caused by infiltration of the disc and optic nerve with abnormal fluids which have been secreted within the cranium, and by increased intracranial pressure have been {773} forced between the sheaths of the optic nerve and between it and its pial envelope. The ingenious explanation proposed by Graefe, that stasis papilla is produced by the damming up of the return blood in the cerebral sinuses, thus causing impeded circulation with increased blood-pressure in the ophthalmic vein and its branch (the central retinal vein), has generally been abandoned since the investigations of Sesemann and Merkel have demonstrated the free anastomosis between the facial and the orbital veins in whatever method the primary congestion may be brought about. The latter part of his explanation, in which he compared the rigid tissue of the lamina cribrosa to a multiplier, by its construction tending to augment any existing plethora in the head of the nerve, is still worthy of consideration. While the theory of vaso-motor paralysis is a most enticing one, it is, however, difficult to understand why paralysis of any of the fibres of the sympathetic should always be accompanied by such a limited local congestion without affecting the retinal tissue in their peripheral parts or without any branch leading to the iris, ciliary body, or choroid. Granting that there is some special filament of the carotid plexus distributed to this region of the nerve, it is hard to comprehend how it can be acted upon by tumors of almost any size or consistence situated in the most varied parts of the brain, and also why pressure on the various portions of the intracranial nerve, chiasm, and optic tracts (which so frequently cause hemianopia and partial atrophies) should not be associated with choking of the disc.

[Footnote 173: _Ophthalmoscopie_, p. 293, 1868.]

[Footnote 174: _Klinische Monatsblätter f. Augenheilkunde_, 1870, p. 100.]

THE LYMPH-SPACE THEORY--Since the anatomical researches of Schwalbe and of Retzius have given us a clear understanding of the lymphatic circulation in the eye, the effusions into the sheaths of the optic nerve that have been found in many cases of choked disc that have been examined post-mortem have been shown to be due to the effects of blocking up of the lymph-channels and of the effusion of cerebral fluids (lymph-pus and blood) in the intervaginal space of the nerve or between it and its pital sheath. In support of this, Manz in 1870 showed that injection of fluid into the cranial cavity of rabbits would produce a marked neuritis which was readily demonstrable by the ophthalmoscope; while Schmidt proved that the spaces of the lamina cribrosa of the optic nerves of the calf could be distended by fluid thus injected. In experiments on the human cadaver the writer has repeatedly seen that colored fluids could be readily driven between the sheaths of the optic nerve by injections from the subarachnoid and subdural spaces, and also that when high pressure was used and the injection made directly into the intravaginal space of the nerve, the fluid found its way from the subdural into the perichoroidal space. He once obtained traces of the colored fluid in the lamina cribrosa of the nerve. Since this mode of communication between the cavity of the cranium and the eye has been duly appreciated, a large number of autopsies have shown that choking of the disc has been accompanied by dilatation of the outer sheath of the nerve by lymph-pus or blood which has found its way down from the cranial cavity. It has also been demonstrated that proliferation of the intravaginal (arachnoid) tissue, and the formation of tumors (psammoma and tubercle) at the distal end of the nerve will produce choking of the disc by causing local accumulations of fluid. On the other hand, there are cases where this distension of the sheaths has been {774} carefully looked for and not found; and those who hold the _vaso-motor theory_ consider that it is in any case an accompanying accident, and not the cause, of the choking of the disc. The experiments of Rumpf and Kuhnt, however, add to its probability, by which the deleterious influence of lymph on the axis-cylinder of nerves adds to the probability of the above theory; moreover, even if it is granted that this accumulation of lymph or other fluid within the sheaths of the optic nerve is the cause of choking of the disc, it seems very unreasonable to the writer to expect to find it in all stages of the complaint. It is everywhere admitted that a cerebral tumor may exist for a long time without causing papillitis, and also that inflammation of the discs may exist for months or years, until they have become entirely atrophic, before the brain disease shall have caused death. Choking of the disc is essentially a temporary symptom. Although severe cerebral irritation may cause a great transient increase of cerebro-spinal fluids, which in their turn may produce the most intense inflammation of the intraocular end of the nerve, yet when the atrophied nerve comes to be examined months or years later they leave no traces sufficiently lasting to positively prove their previous existence. Whatever theory may be adopted as to the mode of production of optic neuritis, its clinical importance is admitted by all. Where it exists on both sides, and is accompanied by other cerebral symptoms, it usually points to increased intracranial pressure.

Since the earliest times, impaired vision and other ocular symptoms have been recognized as accompaniments of diseases of the brain. In more recent, but still preophthalmoscopic, times the statistics showing the percentage of blindness in brain tumor are most interesting: thus, Abercrombie noted failure of vision in 17 (38-5/10 per cent.) out of 44 cases, while Ladame, in a study of 331 cases, estimated that there is disturbance of vision in about 50 per cent. This percentage represents the cases of atrophy consequent upon neuritis only. It must be remembered, however, that many die of the brain disease while the disc is still choked, and that this state of the eye-nerve may exist for a long time without any appreciable failure of vision, making it evident that should we look for choked disc with the ophthalmoscope while there are as yet no symptoms of failing sight, the above percentages would still be higher. In support of this we find that there is a rise of double optic neuritis to 93 per cent. in a series of 88 cases of brain tumor, 43 of which have been recorded by Annuske[175] and 45 by Reich,[176] these being here adduced because in all of them there was a careful ophthalmoscopic examination. Gowers thinks that this is an over-estimate, but admits that optic neuritis occurs in four-fifths (or 80 per cent.) of all cases of cerebral tumor. In considering this question we cannot too carefully keep in view the facts so well stated by Hughlings-Jackson,[177] that optic neuritis is essentially a transient symptom, and that, although it often occurs early in the disease, it may in some cases be developed only in the latter stages of the complaint. Jackson states that he frequently examined a case with the ophthalmoscope in which there was no appearance of choked disc till six weeks before the patient's death, when marked papillitis developed, the {775} autopsy showing a tumor in the left cerebral hemisphere. In fact, where the tumor does not occupy the cortical sight-centres, the intercalary ganglia, or press on the tractus opticus or chiasm, it may exist a long time without producing any affection of the optic nerve or deterioration of vision. No neuritis will take place by increase of intracranial pressure so long as the growth of the tumor is slow and there is a corresponding absorption of brain-substance; but should the growth of the tumor be rapid, or any other cause exist by which increased pressure, with consequent irritation and effusion, would take place, infiltration of the nerve and its sheaths with lymph or inflammatory products would ensue, and give rise to swelling and increased growth of connective tissue. In cases of cerebral tumor, however, and where the growth presses on the intracranial portion of the optic nerves, or where the chiasm is compressed and atrophied by the protuberant and bulging floor of the third ventricle, as in the two cases recorded by Foerster,[178] optic atrophy may be produced without the occurrence of previous choked disc.

[Footnote 175: _A. f. O._, xix., 3, pp. 165, 300.]

[Footnote 176: _Klin. Monatsblätter f. Augenheilkunde_, 1874, pp. 274, 275.]

[Footnote 177: _Med. Times and Gazette_, Sept. 4, 1875.]

[Footnote 178: _G. u. S._, vol. vii. p. 141.]

HEMIANOPIA (HEMIOPIA, HEMIANOPSIA).--We may, however, have serious affections of the sense of sight without any marked alteration in the retina or optic nerve. Careful study of the various forms of hemianopia and other symmetrical defects in the field of vision will often surprise us by the extent of the defect which it reveals, and sometimes serve as a guide to the localization of the cerebral lesion which produces the defect. Hemianopia (or the not-seeing of half an object) is usually of the homonymous lateral variety, in which, if the centre of any object be fixed by the macula lutea of each eye, then either all parts of the object lying to the right-hand side of the points of fixation or else all parts lying to the left of that point become invisible. There may also be temporal hemianopia (hemianopia heteronymous lateralis),[179] in which the nasal side of each retina is blind, and the temporal field of each eye consequently abolished. In such case the right eye sees nothing to the right of the fixation-point, and the left eye nothing to the left of it. The external half of each retina may be blind, in which case there is loss of the nasal field of each eye and of the entire binocular field of vision. In all of these cases the dividing-line between the blind and seeing parts of the retina is a more or less vertical one, but there are also cases where the dividing-line is horizontal, and we thus have an upper or lower hemianopia. From a clinical standpoint the first-named variety (homonymous lateral hemianopia) is markedly distinguished from the others by its usual more rapid development, and by the absolutely sharp dividing-line which runs vertically through the retina at the macula; this field of vision retaining its form without subsequent development of zigzags or other irregularities. All other varieties of hemianopia develop more slowly, and their boundaries--which are usually not perfectly vertical or horizontal, and do not generally extend to the fixation-point--may vary from time to time. The homonymous lateral variety is of far more frequent occurrence than the other forms: out of 30 cases carefully observed by Foerster, where perimetric measurements {776} of the fields were taken, 23 were of this variety, while the remaining 7 presented the heteronymous temporal form. The subject of homonymous lateral hemianopia is so important clinically, and so interesting as regards the probable course of the fibres in the optic nerves, chiasm, and cerebral centres, that it appears desirable to state briefly a few of the most decisive facts in regard to it which have been substantiated by careful autopsies.

[Footnote 179: If we retain the word hemiopia (half-seeing), then this variety is termed medial hemiopia, because the lateral halves of the retina are still intact and vision is practicable in the median or nasal field of each eye.]

1. In 1875, Hirschberg[180] published a case of right-sided homonymous hemianopia with perfect central vision. At first there was no paralysis of sensation or motion, but subsequently aphasia and right hemiplegia set in. The autopsy showed a large sarcomatous tumor which had caused atrophy of the left tractus opticus.

[Footnote 180: _Virch. Arch._, Bd. lxv.]

2. Hughlings-Jackson and Gowers[181] (1875) relate a case of left homonymous hemianopia with hemianæsthesia and hemiplegia of the same side. The autopsy showed softening of the posterior part of the right thalamus opticus without other lesion.

[Footnote 181: _R. L. O. H. Rep._, vol. viii. p. 330.]

3. Curschmann[182] (1879) gives the case of a patient who drank sulphuric acid, which corroded the oesophagus and affected the aorta, causing embolus of the right brachial artery. On the day following there was complete left hemianopia. The autopsy showed a large area of cerebral softening in the right occipital lobe without other lesions. In the discussion of this case at the session of the Berlin Society of Psychiatry and Nerve Diseases, Westphal[183] related a case of unilateral convulsions without loss of consciousness where there was homonymous hemianopia, and in which the autopsy showed a large area of softening in the white substance of the occipital lobe in the side opposite to the defect in the field of vision.

[Footnote 182: _Centralblatt f. Augenheilkunde_, 1879, p. 256.]

[Footnote 183: _Loc. cit._, p. 181.]

These cases might be multiplied, but the writer has selected them because they were made by careful and competent observers, and the lesions were so marked and limited in character as not to allow of any other interpretation than that given. If we admit the validity of the evidence, we have proved conclusively that, from a clinical and a pathological standpoint, binocular homonymous lateral hemianopia may be produced by lesions of the optic tract, of the posterior part of the thalamus opticus, and of the occipital lobe of the brain of the side opposite to the defect in the field of vision; and that, therefore, there must be a partial, and not a total, crossing of the fibres of the optic tracts at the chiasm. Moreover, as Foerster has most pertinently remarked, such a state of affairs does not violate the physiological law of the total crossing of other nerves, because in the binocular field of vision the partial crossing causes all objects to the right of the point of fixation to be seen by the left hemisphere, while those to the left of it are seen with the right hemisphere. While this problem appears sufficiently plain, and the view above advocated is adopted by the majority of writers of the present day, it is by no means equally satisfactory when looked at from a purely anatomical or physiological standpoint. Newton[184] in 1704 had already appreciated the importance and difficulty of the subject, and in {777} the hope that others might further investigate it asked the question whether the fibres from the right sides of both retinæ do not so unite at the chiasm as to go together to the right side of the brain, those from the left side of each retina pursuing a similar course to the left hemisphere. He further remarks that "if he is correctly informed that the optic nerves of such animals as have a binocular field of vision join at the chiasm, while those of the animals who have no binocular vision, such as the chameleon and some fishes, do not so join."[185] Since his day the majority of authors have adhered to this view, until Biesiadecki,[186] by careful anatomical studies and lectures, attempted to prove that in both men and lower animals there is a total crossing of the fibres at the chiasm. Twelve years later Mandelstamm,[187] by clinical observations of nasal hemiopia and dissections of the chiasm, maintained the same view. In the same year Michel[188] supported the same doctrine, and since then Schwalbe[189] and Scheel[190] have each advanced the same view. However, Von Gudden,[191] also basing his opinions upon dissections, takes the opposite ground, and has since endeavored by a series of experiments, in which he enucleated one eye of young rabbits and dogs, to prove[192] that if the animals were allowed to live until central atrophy set in there is a partial atrophy of both optic tracts, more marked on the side opposite to that of the enucleated eye, because the crossed bundle is by far larger than the direct.

[Footnote 184: _Optiks_, London, 1704, p. 136.]

[Footnote 185: _Loc. cit._]

[Footnote 186: "Chiasma Nervorum Opticorum der Menschen und der Thiere," _Sitzungsberichte der Wiener Akadamie_.]

[Footnote 187: _A. f. O._, xix., 2, pp. 39-58.]

[Footnote 188: _Ibid._, xix., 2, pp. 59-84.]

[Footnote 189: _G. u. S._, vol. ii. p. 324.]

[Footnote 190: _Klin. Monatsblätter f. Augenheilkunde_ (extra number 2), 1874.]

[Footnote 191: _Arch. f. Psychiatrie_, vol. ii. p. 21.]

[Footnote 192: _A. f. O._, xx., 2, p. 226, and also _Ibid._, xxv., 1, p. 1, 1879.]

From similar experiments on rabbits, Mandelstamm[193] maintains that there is a total crossing at the chiasm, and Michel,[194] who repeated Von Gudden's experiments, arrived at the same conclusion. Brown-Séquard[195] asserted that a medial cut of the chiasm in rabbits produces amaurosis of both eyes, which would indicate that there is total crossing, while Nicati[196] a year later showed that a median section of the chiasma in young cats did not produce blindness of each eye, the animal following with the eye and the head the movements of a light held at a considerable distance from the eyes.[197] The condition of the optic nerve and brain obtained from the human subject, where by accident or by disease one of the eyes has been destroyed long before death, seems in the main to speak for partial decussation. Thus, Biesiadecki, while maintaining total decussation, could only conclude from such specimens of degenerated nerves and tracts that the greater part of the fibres of the atrophic nerve went to the tract of the opposite side. Woinow[198] demonstrated preparations to the Ophthalmic Society at Heidelberg where the left eye had been blind for forty years, and the atrophy, which had travelled up the left nerve, was plainly visible in both optic tracts. Schmidt-Rimpler[199] also showed atrophy of both tracts {778} more marked in that of the opposite side, and Manz[200] found atrophy of both tracts after atrophy of the nerve of one side; Plink[201] reports a similar state of affairs; while Popp[202] and Michel[203] from analogous specimens draw conclusions favorable to the total crossing.

[Footnote 193: _Ibid._, xix., 2, p. 47.]

[Footnote 194: _Ibid._, xxiii., 2, p. 227.]

[Footnote 195: _Archiv de Physiologie_, 1872, p. 261, and 1877, p. 656.]

[Footnote 196: _Ibid._, 1878, p. 658.]

[Footnote 197: Cats have a larger binocular field of vision, and are better subjects for experiments than rabbits.]

[Footnote 198: _Klin. Monatsblätter f. Augenheilkunde_, 1875, p. 425.]

[Footnote 199: _Ibid._, 1877, "Bericht der Ophth. Gesellschaft," pp. 44-48.]

[Footnote 200: _Klin. Monatsblätter f. Augenheilkunde_, 1877, "Bericht der Gesellschaft," pp. 49, 50.]

[Footnote 201: _Arch. f. Augenh. und Ohrenheilkunde_, vol. v.]

[Footnote 202: Inaug. Diss., _Embolie der Art. Centralis_, Regensberg, 1875, p. 20.]

[Footnote 203: _A. f. O._, xxiii., 2, p. 243.]

The above cases are amongst the most decisive which have been reported, and are quite sufficient to show how great the conflict of opinions is among good observers. The observations and experiments on the subject of sight-centres in the cortex cerebri are also conflicting: thus, while Ferrier places the cortical sight-centre in the angular gyrus, and maintains that its destruction will produce blindness, Luciani and Tamburini agree as to the locality of the sight-centre, but maintain that its destruction produces hemianopia; while Munk places the sight-centre in the occipital lobe, and asserts that its loss causes hemianopia and not contra-lateral blindness. In the case of hemianopia reported by Keen and Thomson,[204] where a bullet wound of the left occipital lobe produced right hemianopia without other apparent lesion, the writer has had an opportunity of personally examining it and of confirming their conclusions. The conclusions which he arrived at, associated with the knowledge which he obtained in Stricker's laboratory by witnessing experiments upon dogs and apes, where portions of the occipital lobes were destroyed, have convinced him that cortical lesions of the occipital lobes produce hemianopia. On the other hand, chiefly on clinical grounds and from the study of hystero-epilepsy, Charcot concludes that the band of uncrossed fibres in the chiasm bends again somewhere in the region of the geniculate bodies to join the crossed bundle once more in the cortical centre. According to this theory, destruction of the cortical centre should produce total amaurosis of the opposite eye, and lesions between the chiasm and geniculate bodies would produce homonymous hemianopia, while pressure in the crossing-point of those fibres (which in the chiasma are uncovered and run from the geniculate bodies to the opposite cortical centre) would give paralysis of the temporal halves of both retinæ.

[Footnote 204: _Trans. A. O. Soc._, 1871.]

As regards pure crossed amblyopia, the scheme of Charcot is scarcely borne out by his clinical facts. The latest theories of those cases which were investigated by Landolt and himself showed, as they reported, marked amblyopia on the opposite side from the lesion, but associated with contraction of the field of vision in the eye of the same side. The question, however, is so vast, and so much remains to be learned concerning the brain-centres and their communications with the optic tracts, that it can scarcely be considered sufficiently ripe for an exhaustive discussion in a paper like the present.

According to Foerster, temporal hemianopia always develops slowly without any concomitant paralytic symptoms: it does not have constant boundaries, and is now progressive and again retrogressive. He cites cases which he has observed for years where at first small negative scotoma appeared just outside of the fixation-point, and increased till there was a total loss of the temporal fields. The line of division between the blind and seeing sides of the field of vision is not sharply defined and {779} not accurately vertical. In some cases there is a gradual invasion of the sound side. Although it is usually assumed that some pressure in the anterior or in the posterior angle of the chiasm is the cause, yet the writer does not know of any post-mortem examination of a case. Mauthner[205] gives short histories of 23 cases of temporal hemianopia, besides 11 cases relating to nasal hemianopia (or, according to his classification, hemianopia heteronyma medialis) from various authors, in most of which the ophthalmoscope showed either the presence of a neuritis or an atrophy of the nerve. There were two autopsies in the cases of nasal hemianopia related by Mauthner--those of Schule and Knapp--one of which showed an enlargement of the third ventricle and infundibulum, with atrophy of the nerves, and the other a high degree of ætheromatous degeneration of arteries at the base of the brain. Any cause which would produce simultaneous pressure on the outer angles of the commissure would give rise to nasal hemianopia. Little is known regarding hemianopia above or below the horizontal line: both Mackenzie and Graefe mention its occurrence, and Knapp, Schoen, and Mauthner give interesting cases. The writer has seen a case in a woman of fifty-five years otherwise apparently in good health. The upper part of each field was wanting, and the line of division ran slightly above the fixation-point, it being nearly horizontal. The optic nerves did not present any marked departure from their normal appearance, and central vision was fair (20/x1). The only autopsy of a case of superior hemianopia with which the writer is familiar is that reported by Russell,[206] in which there was a tumor involving the bones of the base of the cranium. The patient had upper hemianopia, confined to the right eye, followed by total blindness, coming on first in the right and then in the left eye. Genuine binocular hemianopia of the superior or inferior variety is probably produced by some symmetrical affection of the optic nerves between the chiasm and the eyes.

[Footnote 205: _Gehirn und Auge_, 1881, pp. 373-381.]

[Footnote 206: _Med. Times and Gazette_, No. 47, 1873 (rep. _Nagel's Jahresbericht_, 1873, p. 361.)]

In apparently healthy individuals transient hemianopia is not an unfrequent occurrence, and may either develop with or without other cerebral symptoms. It is usually followed or accompanied by headache, or more rarely by vertigo, tinnitus aurium, difficulty of speech, etc. Even in intelligent patients, who have not been drilled by their medical adviser to carefully analyze their symptoms, it is not recognized as half-vision, but here, as in the permanent variety of the affection, it is described as a dimness or blindness of the eye on the side in which the field of vision is defective. Some cases of transient hemianopia are accompanied by peculiar zigzag flickerings of light in the defective portions of the field of vision, which have given it the name of scotoma scintillans. We are fortunate in having an accurate description of this form of the affection by so competent an observer as Foerster, who has frequently experienced it in his own person. In his case the phenomena last from fifteen to twenty-five minutes, and commence with the appearance of dimness in both eyes, which gradually increases to a defect of the field of vision lying to one side of the fixation-point. This is soon followed by a flickering which commences in a zone around the scotoma, and increases centrifugally until it assumes the form of an arc with the convexity outward, {780} the flickering rarely extending beyond the vertical line which separates the two halves of the field of vision. When it has reached the outer limits of the field, it generally diminishes and fades away. From a consideration of the celebrated case of Wollaston, it is probable that transient hemianopia may be caused by some temporary congestion of a brain tumor, but in the majority of instances it is certainly allied to functional disorders like migraine. Transient hemianopia has been observed in several members of the family of one of the writer's patients, all of whom are subjects of consecutive neuralgic headaches. Leber has observed the same thing. Brewster and Quaglino have attributed it to a retinal anæmia, but a careful ophthalmoscopic examination in two well-marked cases (that of Foerster and one related by Mauthner) failed to show any retinal changes. In some cases the well-marked hemianopic character of the attack speaks for its intracranial origin, which may be temporary derangement of the circulation, possibly in the optic tracts. Dianoux tells us that in his case the attack could be cut short by keeping the head down between the legs. In some of the cases which the writer has seen it may be cut short by a liberal dose of whiskey.

Affections of the Third Pair.

While a few words on the pathology of the third and sixth nerves tend to throw light on our knowledge of cerebral localization, they will also spare a good deal of needless repetition in the detailed discussion of the eye symptoms which accompany many well-marked diseases. Complete paralysis of the third nerve may be caused by pressure on its filaments at the base of the brain without other symptoms. Where it occurs with hemiplegia of the opposite side of the body and other cerebral symptoms, it is usually due to pressure on the nerve where it runs beneath the cerebral peduncle: according to Nothnagel,[207] this localization of the disease is still more certain when paralysis of the facial and hypoglossal nerves exists on the same side as the hemiplegia (that is, on the side opposite to the third-pair paralysis). Hughlings-Jackson[208] remarks that the symptoms are only positively diagnostic of a lesion in the neighborhood of the peduncle when they appear simultaneously, but when they are concentric to each other they may be due to an affection of the cranium. Ollivier and Little[209] have each related a case where this group of symptoms has not originated in any lesion in the peduncle, but has been caused by an abscess of the middle and posterior lobes, which secondarily involved these parts.

[Footnote 207: _Topische Diagnostik der Gehirnkrankheiten_, p. 198, 1879.]

[Footnote 208: In Russell Reynolds's _System of Medicine_, vol. ii., 1872.]

[Footnote 209: Robin, _Des Troubles oculaires dans les Maladies de l'Encephale_, p. 95.]

DOUBLE THIRD-PAIR PARALYSIS.--Double third-pair paralysis is rare, but might be produced by any cause acting on both peduncles. Kohts gives a case where such paralysis was caused by a tumor of the size of a cherrystone limited exactly to the posterior tubercles of the quadrigeminal body. Nothnagel remarks that paralysis of corresponding branches of the third pair point to the corpora quadrigemina as the seat of lesion. On the other hand, Panas[210] relates a case of absolute {781} immobility of the eyes where the only demonstrable lesion at the autopsy was a meningo-encephalitis in the lower part of the cerebellum. Robin describes a case of double third-pair paralysis where there were ptosis and dilatation of the pupils, with a loss of all power to move the eyes except downward and outward. The diagnosis was that of an interpeduncular syphilitic gumma: there was complete recovery. In the above case it is interesting to note that while the paralysis of the left eye occurred previous to that of the right, the eye last attacked was the first to regain its motions.

[Footnote 210: Cited by Robin, _loc. cit._, p. 74.]

PTOSIS.--Paralysis of the branch of the third pair which supplies the levator palpebræ, when it exists without any lesion of the other branches or where it is coincident with hemiplegia of the opposite side, is frequently held to indicate a cerebral lesion, which may be either cortical or have its seat in the nucleus of the nerve. According to Grasset,[211] when the lesion is cortical it is situated in the parietal lobe in advance of the angular gyrus. The localization is by no means well made out. Coignt[212] has shown that it is not always crossed, for in 5 out of 20 cases mentioned by him it existed on the same side as the paralysis. Steffen[213] gives a case of double ptosis with sluggish pupils where there was complete control over the muscles moving the globe, the autopsy showing a tubercle in the tubercular quadrigemina which had entirely effaced their normal structure.

[Footnote 211: Robin, p. 104.]

[Footnote 212: _Thèse de Paris_.]

[Footnote 213: _Berliner klin. Wochenschrift_, No. 20, 1884.]

OPHTHALMOPLEGIA INTERNA.--In those cases where affection of the orbital ophthalmic ganglia can be excluded, paralysis of the pupillary and ciliary branches of the third pair is, according to Jonathan Hutchinson, due to an affection of the twig which runs through the lenticular nucleus in the striated body. It is frequently associated with paralysis of the internal rectus, and may be accompanied by paralysis of the ciliary muscle. After diphtheritis there is often paralysis of the ciliary muscle, with prompt reaction of the iris. The writer is not aware of any recorded instance of apoplexy or other sudden onset of disease which would enable us to localize exactly the centre for pupillary contraction. According to Hughlings-Jackson, we may have in apoplexy the most varied states of the pupil (normal, dilated, or contracted) independent of the seat of lesion: he further states that upon calling loudly to the patient there will sometimes be a transient pupillary dilatation. When we look at the state of the pupils as part of general symptomatology, we find a most perplexing confusion and contradiction: in fact, notwithstanding the quantity of material both in ancient and modern literature, we are far from having any satisfactory account of the subject. This is partly due to our imperfect knowledge of the anatomy of the brain and to the great difficulty of estimating exactly pupillary changes, and partly carelessness and want of a proper system of observation. The data have for the most part been hastily compiled, without a minute statement of concomitant symptoms or the stage of the disease in which they are developed. Usually, they have been made without any proper means for illuminating the pupil or apparatus for correctly magnifying and observing its motions. In most cases the want of knowledge of the more common sources of error, such as a difference in the size of the pupils owing to difference in the refraction of {782} the eyes, posterior synechiæ, or other intraocular changes, has invalidated the results.

ASSOCIATED MOVEMENTS OF THE HEAD AND EYES.--In many central lesions, associated movements of the head and eyes are present, and, although the exact channels through which they are propagated are for the most part unknown, yet certain groups of these clinical symptoms are of so frequent occurrence as to be recognized and admitted by almost all observers. Vulpian and Prévost were the first to enter into a minute study of these movements. Vulpian in his lessons on the physiology of the nervous system (1866) states that "in cases of unilateral cerebral lesion, whether it be situated in the cerebral hemispheres, the striated bodies, the thalami optici, the cerebellum, or in the different parts of the isthmus cerebri, whether the lesion be softening or hemorrhage, there is often, immediately after the attack, a deviation of the eyes at the time of development of the hemiplegia. The deviation is in general transient, and may last either a few minutes or hours or several days. The eyes are usually turned in a direction opposed to that of the hemiplegia; thus, if the right side is paralyzed, both eyes are turned toward the left. On regaining consciousness the patient, if he tries to turn his eyes to the right, may either be entirely unable to move them, or, what is more usual, may succeed in bringing them to the middle of the palpebral aperture without being able to turn them farther in that direction. Does this phenomenon depend on a paralysis of the muscles which cause conjugate motion of the eyes, or on a spasmodic contraction of their opponents, over which they are unable to triumph?" He further states: "I incline strongly to the latter view, as it is in accordance with what we observe in animals. The analogy of the phenomena goes still farther: often the head of the patient has made a more or less marked movement of rotation on the neck--a movement as the result of which the face is turned toward the non-paralyzed shoulder, and in the cases where we cannot observe a deviation by turning back the head into its normal position, an action which can often be only brought about by considerable effort."