Motor nerve biopsy: feasibility and safety.

Motor nerve biopsy was attempted on 19 occasions in 18 patients. Nerve tissue was obtained in 16. The nerves biopsied included those to the anconeus (4 times), palmaris longus (6), flexor sublimus (1), triceps (2), extensor carpi radialis (1), quadriceps (1) and gastrocnemius (1). Attempts to biopsy the radial nerve, the nerve to plantaris and the left common peroneal nerves failed in 2 patients. The lengths of nerve obtained varied from 1 to 3 cm, and from 1-5 fasciculi were present in the specimens. Sufficient material for both electron microscopy and teasing was present in 11. No patient experienced increased weakness, but one had transient paraesthesiae in the distal forearm following biopsy of the nerve to the palmaris longus. We conclude that motor nerve biopsy as described is both feasible and safe. The nerve to the palmaris longus, where that muscle was present, provided the optimum specimen for pathological studies.