Probable neurosyphilis-associated longitudinally extensive transverse myelitis with severe bladder dysfunction and radiologic resolution: a case report

Abstract Background Longitudinally extensive transverse myelitis (LETM) is often investigated as an autoimmune inflammatory myelopathy, but treatable infectious mimics should also be considered. Neurosyphilis-associated myelitis is uncommon and may resemble aquaporin-4 or myelin oligodendrocyte glycoprotein antibody-associated disease. Case presentation A 31-year-old man presented with a one-month history of progressive bilateral lower-limb thermal dysesthesia and hyperesthesia, proximal leg weakness, pyramidal signs, urinary retention, and fecal incontinence. Spinal magnetic resonance imaging showed a longitudinally extensive central thoracic cord T2 hyperintensity from T6 to T10. Serum syphilis serology and cerebrospinal fluid Venereal Disease Research Laboratory testing were reactive, whereas human immunodeficiency virus testing was negative, serum aquaporin-4 and serum myelin oligodendrocyte glycoprotein antibodies were negative, and oligoclonal bands were absent. Because the initial cerebrospinal fluid sample was blood-contaminated and showed no pleocytosis, the diagnosis was considered probable neurosyphilis-associated LETM rather than definitive syphilitic myelitis. The patient received ceftriaxone-based anti-treponemal therapy with adjunctive corticosteroids. Follow-up cerebrospinal fluid Venereal Disease Research Laboratory testing became non-reactive, spontaneous voiding recovered, and follow-up spinal magnetic resonance imaging showed radiologic resolution. Conclusions Probable neurosyphilis-associated LETM can mimic seronegative inflammatory myelitis. Syphilis testing should be considered early in LETM, particularly when prominent sphincter dysfunction is present. Diagnostic certainty may be limited by atypical cerebrospinal fluid findings, blood contamination, and concomitant antimicrobial and corticosteroid treatment.