Hereditary sensory radicular neuropathy : a family study / David C. Wallace.

  • Wallace, David C.
Date:
1970
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Hereditary sensory radicular neuropathy : a family study / David C. Wallace. Source: Wellcome Collection.

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    Other Investigations 29 In the most severely affected, VII 100, electrical studies were performed on the right ulnar nerve. It vi^as not possible to record afferent volleys either from the fifth digit to the wrist or from the wrist to the elbow. This indicated a complete absence of any distal evidence of surviving sensory fibres. There was evidence of gross depletion of the motor fibres to the intrinsic muscles of the hand. More interesting were the findings on VII 95, and the report is quoted in to to : The left extensor digitorum brevis and tibialis anterior muscles were sampled with concentric needle electrodes. There was fibrillation, but there was a moderate reduction in the number of motor units under voluntary control. Despite a reasonably normal response from the tibialis anterior, no motor response was obtained from the extensor digitorum brevis when the lateral popliteal nerve was stimulated at the knee, and this was also the case when the stimulus was applied at the ankle. No apparent volleys could be recorded over the lateral popliteal nerve at the knee. A sensory potential recorded over the left median nerve at the wrist had an amplitude of 12 fxv and a latency of 2-4m.sec. A mixed nerve action potential recorded at the elbow had a latency of 4-8 m.sec. and an amplitude of 21 fiv. There is evidence of both motor and sensory involvement in the lower limb, but the sensation appears intact in the upper limb. The interesting feature here is the definite proof found of the existence of impairment of motor nerve function in a subject showing no clinical evidence of muscle weakness. It is possible that this state of affairs may exist in people from other families showing the clinical picture of a purely sensory neuropathy. Case VII 80 is a nineteen-year-old girl in whom there is some doubt regarding the existence of the disease. She gets quite severe parsesthesise, and the writer has found on occasions anaesthesia to temperature and light touch of two of her toes. These changes have not been confirmed by others who have examined her. Motor and sensory studies were performed on the right lateral popliteal nerve. These were both within normal limits, but it was of interest to note that the motor conduction velocity was faster than the sensory conduction velocity. This patient will need to be observed over some years before any conclusions can be drawn regarding this finding. In summary, it can be said that electromyography has confirmed the loss of function of the peripheral nerve fibres. It has shown the presence of changes in motor conduction in cases where muscle weakness is not clinically detectable, and it may prove possible by its use to determine the presence of the trait before the development of unquestionable sensory signs. Histopathology From Case VII 100, a biopsy of the lateral popHteal nerve was taken. This showed a degenerate piece of nerve tissue in which bundles of amyelinate fibres were arranged in a normal manner in a somewhat thickened perineurium. No morphological appearance suggestive of amyloid could be seen, and no metachromatic substance was demonstrable. The appearances were in every way similar to peripheral nerve which had undergone degeneration after neurotmesis. Because of the difficulty in some of the younger subjects and in females of determining on clinical grounds whether they carry the trait, some form of discriminating examination would be most useful. Electromyography may fulfil this purpose, but this is not yet certain. Another method which holds some promise, \