[Electrophysiological studies in vincristin-polyneuropathy (author's transl)].

21 Patients with malignant brain tumors were treated with vincristine (1,4 mg/m2) in the course of combination chemotherapie, given in 14 days series over 3 months up to 26 month. 18 patients developed clinical signs of a sensory and 4 patients of a sensomotoric polyneuropathy. Changes in nerve conduction velocity of the N. peronaeus and N. suralis and amplitude of the evoked muscle response (M. extensor digitorum brevis) and nerve action potential were studied in dependency of the total vincristine dosage. The following conclusions were drawn. 1. Clinical occurrence of vincristine polyneuropathy and decrease of nerve conduction velocity of peroneal and sural nerve and the amplitude of the muscle response and nerve action potential are dosage dependent. 2. Sensory fibres appear to be damaged earlier and more severe than motor fibers, but this difference was statistically not significant. 3. Nerve conduction velocity of peroneal and sural nerve is normal or slightly decreased in vincristine polyneuropathy, but the amplitude of the evoked response in extensor digitorum brevis muscle and of the nerve action potential of the suralis nerve are markedly diminished. This result indicates that vincristine polyneuropathy is of primary axonal orgin. 4. If vincristine dosage is reduced to half or vincristine is discontinued after a reduction of the potential amplitude in the extensor digitorum brevis muscle below 1 mV, severe, not reversible polyneuropathies may be avoided.