An American text-book of diseases of the eye, ear, nose and throat / edited by G.E. De Schweinitz and B. Alex. Randall.

Date:: 1899

Credit: An American text-book of diseases of the eye, ear, nose and throat / edited by G.E. De Schweinitz and B. Alex. Randall. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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$has been changed chiefly in appearance, without sufficient increase in volume tu cause atrophy of the nerve-libers. Etiology.—It is evident that any of tl auses which have been enum- erated as producing optic neuritis may produce atrophy, and, as the signs of neuritis may have disappeared by the time the patient is first examined, the results of the cause may lie set down as atrophy without any knowledge of the neuritis. Besides neuritis, any other cause that cuts off communication between the retina and the higher nerve-centers will produce atrophy. Brain-tumors may cause atrophy, by the production of neuritis, by direct pressure on the nerve, chiasma, or tracts, by the pressure upon the chiasma and tracts of the accumulation of fluid in the ventricles which often accom- panies them, or by raising up the chiasma and nerve, and thus causing them to be constricted by the arteries at the base of the brain. Injuries In tin nerve-trunk are followed by atrophy, both ascending and descending, while all the various processes which destroy the function of the retina, whether it lie removal of the globe, the various conditions which pro- duce phthisis bulbi, inflammations of the choroid or retina, detachment of the latter, or cutting off its blood-supply through thrombosis or embolism, and, finally, abnormal pressure both upon the retina and the disk, as in glaucoma, produce ascending atrophy of the nerve-trunk, chiasma, and the tracts leading to the higher cerebral centers. The atrophy which sometimes follows erysipelas of the face is undoubtedly caused by the accompanying inflammation in the orbit, since any severe orbital cellulitis may cause atrophy, probably either by direct pressure on the nerve- trunk, by thrombosis of the retinal vein, as pointed out in particular by Knapp, or by producing a neuritis. Some authors doubt whether atrophy may result simply from hemorrhage into tin orbit, but the writer has seen at least two cases in which this undoubtedly occurred : in one a hemorrhage fol- lowed an extirpation of the lachrymal aland and led to atrophy, with the typical picture of thrombosis of the retinal vein and paralysis of all the ocular muscles ; this indicating that even if the vein had not become obstructed, atrophy might have resulted directly from the pressure. In a number of case- optic-nerve atrophy follows/aSs or blows upon tin head., without any signs of meningitis or optic neuritis. The first rational explanation of these cases was given by Holder and Berlin, who found that in many eases, without any external signs of fracture, fissures of the wall- of' the orbit were produced which extended into the optic canal, the nerve in sonic cases apparently being injured immediately by pressure from fragments of the bone or by hemorrhages into the optic canal, or later by pressure from the development of callus. In the first two instances blindness develops at once ; in the last it comes on gradually after several days or weeks. These cases are generally one-sided, and apparently may lie produced through contre-coup by violence to distant parts of the body. Whether the cases described by Schwcigger as com-nxsion of the optic nerve were due to fractures of the bone is uncertain. In them violence to the head was followed by immediate and complete one-sided amaurosis. A certain amount of useful vision (in one case nearly approaching the normal, the nerve showing partial atrophy) returned after some days or weeks. It is possible, also, that some of the atrophies which follow spinal injuries are produced in this way : about the real significance of these cases there has been some dispute, some authors leaning to the view that they were the result of a trophic disturbance, while others assume that they result from an ascending meningitis; but since it lias been shown that a fall upon the trochanter, for instance, can produce a frae-$