Segmental zoster paresis of the lower limb with multisegmental lumbosacral plexus involvement: a case report and literature review

Segmental zoster paresis (SZP) of the lower limbs is an uncommon complication of herpes zoster (HZ). Its atypical presentation and variable prognosis make early recognition and comprehensive intervention essential. We describe a patient who developed sciatica, ipsilateral herpetic vesicles on the calf, and subsequent lower limb paralysis but achieved full functional recovery within two months. A 73-year-old man presented with a 6-day history of persistent left lower back pain radiating to the left lower limb. He was initially diagnosed with sciatica after lumbar magnetic resonance imaging (MRI) revealed disc abnormalities. The appearance of scattered erythematous vesicles along the left L4-L5 dermatomes led to a revised diagnosis of HZ, prompting the initiation of antiviral, corticosteroid, and analgesic therapies. One week after the resolution of the rash, the patient developed new-onset motor weakness in the left leg; manual muscle testing demonstrated grade 3-/5 strength in the left iliopsoas and quadriceps femoris. Laboratory tests revealed dysglycemia and T-cell dysfunction. Electrophysiological studies confirmed neurogenic involvement of the L2-S1 spinal segments, establishing the diagnosis of SZP secondary to HZ. Following continued neurotrophic therapy and structured, intensive rehabilitation, the patient demonstrated progressive improvement, achieving complete motor recovery within two months. Early identification of risk factors, timely diagnosis, and aggressive multimodal management are crucial for optimizing functional recovery in individuals with lower limb SZP. Enhanced clinical awareness is essential to prevent long-term disability and avoid unnecessary interventions. Further studies are needed to establish standardized treatment guidelines.