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THE LABYRINTH AND THE EIGHTH NERVE 393
DEAFNESS DUE TO MUMPS, ETC.
Mumps may produce labyrinthine deafness. The pathology of the condition
is not known with certainty. It may be due to meningitic neurolabyrinthitis
or to metastatic infection of the cochlea by way of the blood stream. Petechial
haemorrhages in the medulla in the region of the cochlear nerve have been
recorded. The vestibular reactions may be normal although there is complete
deafness in the affected ear. In half of the cases one ear only is affected.
Deafness usually comes on about the fourth or fifth day of the disease, some-
times later, and does not pass off.
Influenza is sometimes followed by tinnitus and nerve deafness, which is
probably due to toxic neuritis. Isolated affection of the vestibular nerve may be
associated with the sudden onset of vertigo, vomiting and rotatory nystagmus.
Both parts of the eighth nerve may be involved. The symptoms may persist
for weeks or even months.
Nerve deafness may occur in typhus fever, and it is sometimes an early
feature of disseminated (multiple} sclerosis, in which defects of the auditory
field comparable to defects in the ocular field have been observed.
DEAFNESS DUE TO VITAMIN DEFICIENCIES
The nervous lesions, including degeneration of the cochlear and vestibular
divisions of the eighth nerve, occurring in young, growing, experimental
animals deprived of vitamin A, but provided with vitamin D, have been
explained on the basis of disproportionate growth of the nervous and skeletal
Vitamin B Complex. Deafness and vestibular disturbance were a frequent
occurrence in association with the severe nutritional disorders of the nervous
system which occurred in prisoners of the 1939-45 war. While there is ample
evidence that lack of the vitamin B complex leads to disturbances of the
nervous system, the question of which particular member or group of
members, known or unknown, is concerned with these disorders remains
SENSORINEURAL DEAFNESS OF DOUBTFUL ORIGIN
It must be admitted that in many cases of nerve deafness, whether of sudden
or gradual onset, the cause cannot be ascertained. In cases of sudden onset,
vasospasm or thrombosis involving the internal auditory artery may be
responsible, while a possible virus infection should not be overlooked. Such
cases should be treated as an emergency and appropriate measures may
include repeated stellate ganglion block, administration of a vasodilator
drug such as nicotinic acid or anticoagulant treatment. In the young or
middle-aged serological examination of the blood for syphilis and cerebro-
spinal fluid is advised.
Certain cases of otosclerosis, in which the focus of spongification affects
the capsule of the cochlea in a region away from the oval window, present
the signs and symptoms of sensorineural deafness (atypical otosclerosis) and
not those of a middle ear or obstructive deafness. Such cases are rare as
compared with those in which the deafness is of the middle ear type; but, as