C8 myotome herpes zoster paresis.

Herpes zoster (HZ) infection is a reactivation of latent varicella zoster virus that causes pain and a rash in a dermatomal distribution. Previous reports suggest that 0.5-5% of HZ infections are associated with a myotomal paresis but the incidence may actually be much higher. We present a patient with HZ infection who had persistent right upper extremity weakness after resolution of the rash. Electrodiagnostic studies demonstrated decreased amplitudes in the median and ulnar nerves as well as denervation in the right C8 myotome. Repeat studies showed interval C8 reinnervation as well as normal nerve conduction studies.