Zoster-associated mononeuropathies (ZAMs): a retrospective series

Zoster-associated limb paresis is an uncommon complication of herpes zoster (HZ) and one whose precise pathophysiologic mechanism is poorly understood. Occasionally, the paresis results from a zoster-associated mononeuropathy (ZAM).

Mayo Clinic records between 1996 and 2010 were reviewed for patients with ZAM whose clinical, electrophysiologic, and radiographic features were then abstracted.

Ulnar (2), median (3), femoral (1), and sciatic (2) mononeuropathies were identified. Most patients had moderate to severe weakness in affected muscles, and most had post-herpetic neuralgia (88% at 1 month and 71% at 4 months). The minimum duration of weakness was prolonged (mean, 281.9 days; range, 45-1242 days). Nerve magnetic resonance imaging (MRI) was abnormal, demonstrating nerve enlargement (4/4 cases), T2 signal hypertintensity (2/4 cases), or enhancement (1/4 cases).

While ZAM is an uncommon occurrence following cutaneous HZ, it is associated with significant weakness, high rates of post-herpetic neuralgia, and prolonged morbidity.