Concurrent Spinal Dural Arteriovenous Fistula and Varicella-Zoster Virus Meningoencephalitis Unmasked by Corticosteroid-Associated Deterioration: A Case Report on the Diagnostic Value of Serial mNGS.

backgroundConcurrent spinal dural arteriovenous fistula (SDAVF) and varicella-zoster virus (VZV) meningoencephalitis are exceptionally rare, and overlapping features can delay diagnosis. This case adds to the literature by illustrating how corticosteroid exposure before exclusion of vascular and infectious mimics may be followed by neurological deterioration, and by emphasizing the diagnostic value of serial metagenomic nextgeneration sequencing (mNGS). CASE PRESENTATION: A 48-year-old man developed insidious bilateral lower-limb weakness that progressed to numbness, sphincter dysfunction, and near-paralysis. Initial spinal magnetic resonance imaging showed diffuse thoracolumbar cord lesions; cerebrospinal fluid studies were mildly inflammatory, and myelitis was suspected. He received methylprednisolone pulse therapy followed by oral corticosteroids without improvement. One month later, he presented with fever, severe headache, vomiting, worsening paralysis, and altered mental status. Cerebrospinal fluid demonstrated marked pleocytosis, hypoglycorrhachia, and elevated protein, and mNGS detected abundant VZV sequences. Brain imaging showed hydrocephalus, meningeal enhancement, multifocal ischemic lesions, and intracranial arterial stenoses, consistent with VZV meningoencephalitis and vasculopathy. After external ventricular drainage, intravenous acyclovir, dexamethasone for cerebral edema, and empirical anti-tuberculosis therapy, serial mNGS showed a reduced VZV burden. Repeat spinal imaging revealed tortuous perimedullary vessels and hemosiderin deposition, and angiography confirmed SDAVF from the left T10 intercostal artery. The fistula was coagulated. At 12-month follow-up, he regained slight right-leg movement and partial sensory recovery above L1.

conclusionProgressive myelopathy with atypical inflammatory features should prompt vascular evaluation and pathogen testing. Serial mNGS can identify coexisting infection, guide therapy, and help avoid hazardous empirical corticosteroid use when the diagnosis remains uncertain.