Subacute histopathological features in a case of varicella zoster virus myelitis and post-herpetic neuralgia.

Introduction: Post-herpetic neuralgia is a crippling complication of varicella zoster virus (VZV) reactivation, also known as zoster disease. In rare cases, VZV spreads to the spinal cord and causes myelitis. There is a paucity of data on spinal cord histopathology in the subacute phase of post-herpetic neuralgia and VZV myelitis.

Case description: In this report, we present a case of post-herpetic neuralgia in a patient who died 5 weeks after initiation of symptoms. Autopsy limited to the spinal cord revealed severe tissue vacuolization associated with macrophage and lymphocytic infiltration that was most intense in the right posterior horn, corresponding to an area of magnetic resonance imaging (MRI) T2-weighted hyperintensity. There was some extension of the inflammatory response to the ipsilateral posterior column, dorsolateral column, precentral gray matter, and contralateral lateral column. No significant axonal or myelin loss was observed. Nerve roots and meninges were free of significant inflammation.

Discussion: Our findings provide histopathological insight into early subacute changes in post-herpetic neuralgia and suggest the involvement of the cord and subsequent macrophage and lymphocyte inflammatory response may lead to pain fiber irritation and the clinical pain syndrome of post-herpetic neuralgia.