No abstract

The 8th cranial nerve has been dissected from 23 adult temporal bones at autopsy and studied histologically. It was found that neuroglial tissue, continuous with that in the brain stem, supported 8th nerve axons to just beyond the mid-point of the nerve. Lateral to this, axons are supported by Schwann cells and neurilemmal sheaths with a short 'junctional zone' intervening. The point at which the transition occurred, from neuroglial to Schwann cell portions, was medial to the porus in 56 per cent of cases, level with the porus in 18 per cent, and within the internal auditory canal in 26 per cent. The relevance of these findings to some aspects of 8th nerve pathology and surgery is discussed.

A clinical assessment of the relative values of the hot, the cold and the bithermal hot and cold caloric tests was carried out in a group of normals as compared to patients suffering from vestibular neuronitis, Ménière's disease, head injuries and acoustic neuromas. Results indicate that the hot or the cold test alone does not provide as much information as the bithermal test. A correlation of this result was made to the presence of a spontaneous nystagmus, positional nystagmus and directional preponderance. These forms of nystagmus present are unable to predict the indication for the hot caloric test alone. It is concluded that bithermal tests be continued until further progress on standardization and normal data are available for each of the three sets of tests, obtained separately.

The transmission of nerve-impulses in the labyrinth has been an important physiological problem for some time. Much knowledge was obtained by electro-physiological methods about the function of both the cochlear and the vestibular end-organs. Recently the exist ence of a system of cholinergic nerve fibers has been demonstrated in the organ of Corti by Schuknecht and in the vestibular receptors by Dohlman. It is the purpose of our experiments to find additional information regarding the vestibular cholinergic mechanism.Histochemical experiments of Schuknecht and Churchill showed that acetylcholin, together with the enzyme acetylcholin-esterase, is present in nerve fibers and nerve-endings of the organ of Corti, prob ably mediating the chemical transmission of the impulses in some synaptic regions of the cochlea. 1 It may be assumed that the choliner gic nerve endings during nerve stimulation release acetylcholin which, after acting as transmitter substance, is hydrolized by the enzyme From the