1531 - Proximal Leg Weakness Following Varicella-Zoster Virus Infection: A Case Report of Segmental Zoster Paresis

Case Diagnosis: A 71-year-old man presented with acute right-sided proximal leg weakness and dysesthesias following a herpes zoster rash in the L3–L4 dermatome. He was diagnosed with segmental zoster paresis (SZP), a rare motor complication of varicella-zoster virus (VZV) reactivation.

Case Description: The patient developed a dermatomal vesicular rash, followed by sensory symptoms and progressive leg weakness during the rash outbreak. He received oral antiviral therapy without clinical improvement in two months. Electrodiagnostic studies showed acute denervation in L3–L4-innervated muscles, most consistent with radiculopathy. MRI of the lumbar spine and lumbosacral plexus excluded concurrent compressive or infiltrative causes. He began intensive outpatient rehabilitation. Fluoroscopically guided transforaminal epidural steroid injections were trialed without significant relief of dysesthesia or motor deficit. At seven months, he has demonstrated gradual motor recovery.

Discussions: SZP is an underrecognized complication of VZV reactivation, occurring in approximately 0.5–5% of cases, with higher prevalence in older adults and immunosuppressed individuals. Weakness typically arises within days to weeks of rash onset and results from viral spread from the dorsal root ganglion to motor neurons. Prompt diagnosis facilitates timely antiviral therapy, which may reduce the risk, severity, and duration of paresis. It also prevents misdiagnosis as structural radiculopathy and enables appropriate rehabilitation planning. Diagnosis is clinical, supported by electrodiagnostic findings and variable MRI changes. NAAT or CSF PCR may assist in atypical cases.

Conclusions: SZP is an uncommon but clinically significant cause of acute limb weakness, particularly in older adults. Early recognition—via EMG, imaging, and viral testing—not only guides management but also helps avoid unnecessary interventions. Antiviral therapy may lessen symptom burden and promote recovery. Although two-thirds of patients recover fully or nearly so, persistent deficits may occur, especially with severe initial weakness or advanced age. Physiatrists play a critical role in timely diagnosis, interdisciplinary care, and rehabilitation.