Seropositive NMOSD following herpes zoster infection: a rare case of concurrent LETM and optic neuritis

Background. Neuromyelitis optica spectrum disorder (NMOSD) is a chronic autoimmune condition affecting the central nervous system. Infections, such as herpes zoster, have also been identified as potential triggers. We present a rare case of AQP4-IgG seropositive NMOSD following herpes zoster infection, with simultaneous LETM and ON. Case report. A 39-year-old woman presented with progressive lower extremity weakness and numbness over two weeks, with subsequent bilateral blurred vision. Past medical history was notable for herpes zoster infection affecting the left T5 dermatome two weeks prior, treated with oral acyclovir. Neurological examination revealed paraparesis (MRC grade 3), decreased bilateral Achilles reflexes, and hypoesthesia in the dermatomal distribution of L2 and below bilaterally. Spinal MRI showed a T5–T7 hyperintense lesion consistent with LETM. Serum analysis was positive for AQP4-IgG. VEP confirmed bilateral optic neuritis. She was treated with intravenous corticosteroids and plasmapheresis, resulting in marked improvement in motor strength and sensory symptoms. Three months later, there was complete resolution of motor weakness, with minimal residual radiating pain and episodic blurred vision. Conclusions. The temporal proximity between herpes zoster infection and the onset of NMOSD suggests a causal relationship. It is important to recognize herpes zoster as a possible trigger for NMOSD, including the manifestation of concurrent optic neuritis and LETM. Early diagnosis and immediate treatment might help improve the condition.