Herpes Zoster-Associated Common Peroneal Mononeuropathy

Although herpes zoster can cause various motor complications, mononeuropathy of the lower extremities is rare.We report herpes zoster-associated common peroneal mononeuropathy in a 62-year-old woman receiving immunosuppressive therapy.She initially presented with persistent low back pain radiating from the left buttock to the lateral calf.Erythematous vesicular lesions appeared on the lateral left calf the next day, and acute left foot drop developed 2 days later.Electrodiagnostic studies 5 weeks after symptom onset confirmed left common peroneal neuropathy.She received antiviral therapy, analgesics, and comprehensive rehabilitation.By 9 months after symptom onset, ankle and great toe dorsiflexion had improved to Medical Research Council grade 4; by 11 months, she had regained independent ambulation.Herpes zoster-associated common peroneal mononeuropathy may warrant consideration in patients with acute foot drop, particularly when cutaneous lesions are also present.