Zoster-associated mononeuropathies (ZAMs): A retrospective series

Introduction: 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). Methods: Mayo Clinic records between 1996 and 2010 were reviewed for patients with ZAM whose clinical, electrophysiologic, and radiographic features were then abstracted. Results: 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). Conclusions: While ZAM is an uncommon occurrence following cutaneous HZ, it is associated with significant weakness, high rates of post-herpetic neuralgia, and prolonged morbidity.