Indication of peripheral nerve hyperexcitability in adult-onset subacute sclerosing panencephalitis (SSPE).

Subacute sclerosing panencephalitis (SSPE) is a rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection of immune-resistant measles virus. Diagnostic hallmarks include widespread cortical dysfunction on EEG, myoclonus, white matter abnormalities on neuroradiological examination and the presence of IgG anti-measles antibodies in the cerebrospinal fluid. We present the first case of SSPE with signs of peripheral nerve hyperexcitability, observed as extra discharges following the compound motor action potential at motor nerve stimulation. In addition we demonstrate the importance of SSPE in the differential diagnosis of adult patients with psychiatric and neurological symptoms.