[Hereditary sensorimotor neuropathy in electrophysiological studies]

We performed clinical and electrophysiological studies in 42 children with hereditary motor and sensory neuropathy type I and II (HMSN I and II) and in 103 members of their families. In 24 families with HMSN I the conduction velocity and latency were markedly changed in the nerves innervating the distal muscles (median, peroneal nerves) as well as proximal muscles (facial, axillary and musculocutaneous nerves). The changes were uniform in all motor and sensory nerves studied in a particular patient. The intensity of changes was similar in members of their families even when the clinical abnormalities were minimal, thus the degree of conduction velocity slowing was uniform within families. In adults with HMSN I (group A i B) we found less marked slowing of nerve conduction as compared to children (group P), the difference being significant (p < 0.001). It may suggest a slow process of peripheral nerves maturation despite the existing morbid condition. In patients of 18 families with HMSN II slight changes in conduction velocity were found only in nerves innervating the distal muscles, more evident in legs (peroneal and sural nerves). Conduction time of facial, axillary and musculo-cutaneous nerves was normal. The values of nerve conduction were not changing with patients' age. We recommend examining conduction time in facial, axillary or musculocutaneous nerve as a useful procedure for differentiation between HMSN I and II, especially in families with borderline conduction values in the nerves innervating distal muscles.