Generalized Muscular Stiffness, Fasciculations, and Myokymia of Peripheral Nerve Origin

THE PERIPHERAL nerve disorders, unlike central nervous system and muscle diseases, have not been widely recognized as causes of generalized muscular stiffness. Isaacs,^1,2 in 1961 and 1967, reported three patients with an entity of generalized muscular stiffness, fasciculations, continual electromyographic (EMG) activity at rest and depressed deep tendon reflexes. The muscular stiffness and continual EMG activity were abolished by curare but persisted during spinal anesthesia and after peripheral nerve blocks, suggesting that the syndrome was due to isolated, spontaneous, peripheral nerve hyperactivity. Isaacs also discovered that diphenylhydantoin (DPH) induced a substantial and sustained decrease in the muscular stiffness. Similar cases were reported by Mertens and Zschocke³ and by Levy et al,⁴ both groups confirming the effects of spinal anesthesia and curare. Mertens and Zschocke³ also found carbamazepine as effective as DPH in treatment. Sig

wald et al,⁵ Gardner-Medwin and Walton,⁶ and Hughes and