Varicella zoster infection-associated progressive encephalomyelitis with rigidity and myoclonus in a 6-month follow-up.

A patient with reactivated varicella zoster virus (VZV) manifesting in the left-sided dermatome L3 and S2-S4 developed tonic spasms which morphed into myoclonic jerks, paresis, rigidity and hypoesthesia of the left leg. Later, stimuli-sensitive myoclonus progressed to affect the upper body and was accompanied by fever surges with high-frequency myoclonus, hypertensive derailment, dysphagia and other features of the brainstem with autonomic dysfunction. Cerebrospinal fluid tested positive for VZV, MRI showed no signs of myelitis and EEG was negative for epilepsy. However, on clinical presentation, progressive encephalomyelitis with rigidity and myoclonus, a variant of the more well-known stiff person syndrome, was suspected and later supported by positive serum testing for associated anti-glycine receptor antibodies. Initially established antiviral, anti-epileptic and symptomatic treatment was then extended with intravenous immunoglobulin therapy. Only additional corticosteroid treatment led to a reduction in myoclonus, and uptitration of benzodiazepines decreased rigidity.