Magnetic Resonance Imaging-Negative Varicella Zoster Virus Plexopathy in a Young Patient: A Case Report.

Varicella zoster virus (VZV)-associated plexopathy mainly occurs in patients over 60 years old. Postherpetic neuralgia is a well-known complication of herpes zoster (HZ); however, segmental zoster paresis secondary to HZ was reported in 1-20% of cases in the literature. Magnetic resonance imaging (MRI) findings may be positive in up to 70% of the patients. We describe a 43-year-old male patient with a history of grade two left frontal oligodendroglioma, which was treated with two partial resections, radiation treatment and procarbazine/lomustine, who presented with left upper extremity pain and developed a blistering rash in a dermatomal pattern in the left proximal upper extremity two weeks after the initial symptoms. He was diagnosed with shingles and treated with steroids and acyclovir with minimal improvement. Six weeks after the initial symptoms, a physical exam revealed left deltoid, supraspinatus and infraspinatus weakness with normal muscle stretch reflexes and decreased sensation on the C5 dermatome. Electromyography (EMG) revealed absent left lateral antebrachial cutaneous sensory nerve action potentials (SNAP) amplitude and a small left radial SNAP amplitude compared to the right side. Evidence of ongoing denervation with reinnervation was seen in the left upper trunk-supplied muscles. MRI of the brachial plexus was negative for any abnormalities. The patient was diagnosed with VZV-associated plexopathy, which improved with pregabalin and physical therapy. Our patient was significantly younger than expected in the HZ group. MRI usually shows T2 hyperintensities and thickening of the nerve roots in patients with VZV-associated plexopathy. However, the presentation, onset of symptoms, characteristics of the rash, and clinical course were diagnostic of HZ, and the weakness pattern, supported by the EMG findings, was diagnostic of VZV-associated plexopathy.