Pseudomyotonia in Cervical Root Lesions With Myelopathy

Abstract

Three cases of chronic cervical intervertebral disk protrusion with associated myelopathy at C5-6 level presented the so-called pseudomyotonic reaction on relaxation of grip. They were studied clinically and electromyographically. This phenomenon of slow extension of fingers, resembling grip myotonia, was associated with neurogenic atrophy; it was exaggerated by repeated movements: it occurred either unilaterally or bilaterally; there was no mechanical or percussion myotonia. In all these characteristics it differed from the true myotonic reaction. This phenomenon occurs as a result of simultaneous contraction of the antagonistic muscles of the extensor and flexor muscles of the forearm. It probably results from misdirection of the regenerated radial nerve in relation to the median nerve at the level of nerve root.