Hereditary motor and sensory neuropathies (HMSN). Retinal involvement and ERG alterations

Hereditary motor and sensory neuropathies (HMSN) is a complex group of diseases, mainly of unknown etiology. In 1975, Dyck proposed a classification based essentially on the type of hereditary transmission, nerve conduction velocity and histologic aspect of small nerve biopsies. Hagberg & Westerberg (1983) proposed a new classification. The association between HMSN and retinitis pigmentosa or optic atrophy is sometimes described. Analysing the reported cases, it became evident that the neurologic disease was not clearly defined and the ophthalmologic examination rarely made. In most cases, ERG data were lacking. The authors studied the ocular involvement with ERG in nine patients. The ERG was low in only one patient. Their study suggests that ERG may be a useful approach for the differential diagnosis in some forms of HMSN.