Serial electrodiagnostic studies in West Nile virus-associated acute flaccid paralysis.

A man in his 70s presented for acute rehabilitation with severe acute flaccid asymmetric weakness in both lower limbs. Cerebrospinal fluid and serum immunoglobulin M titers were positive for West Nile virus. Electrodiagnostic studies demonstrated severe diffuse motor axonopathy consistent with an anterior myelitis. Electrodiagnostic and clinical improvements were monitored. Electrodiagnostic testing at 6 and 18 mos demonstrated continuing reinnervation; nascent voluntary motor unit action potentials were first noted proximally and, at 18 mos, distally in the left lower limb, including muscles in which motor unit potentials were not initially noted. Corresponding clinical improvements, though slow, were demonstrated even at 1(1/2) yrs after onset. Thus, motoric changes after West Nile virus-associated anterior myelitis need to be monitored over a prolonged time period to allow accurate assessment of prognosis for recovery in rehabilitation programs.