Optochiasmatic arachnoiditis as a paradoxical reaction in tuberculous meningitis: a case series from Sri Lanka

Tuberculous meningitis (TBM) is the most severe manifestation of central nervous system tuberculosis and is often complicated by paradoxical reactions despite appropriate anti-tuberculous therapy. One of the most devastating forms of paradoxical worsening is optochiasmatic arachnoiditis (OCA), a vision-threatening inflammatory condition involving the optic nerves and chiasmatic cisterns. We describe three HIV-negative patients treated for TBM in Sri Lanka who developed optochiasmatic arachnoiditis as a paradoxical reaction during the course of therapy. Clinical features, cerebrospinal fluid profiles, neuroimaging findings, treatment strategies and outcomes were reviewed. All three patients initially demonstrated clinical improvement following initiation of anti-tuberculous therapy before developing neurological and radiological deterioration consistent with paradoxical reactions. Neuroimaging revealed suprasellar tuberculomas and basal cisternal involvement affecting the optic pathways in all cases. Management required prolonged high-dose corticosteroid therapy. Adjunctive immunomodulatory therapy, including thalidomide, was administered in selected cases. Despite intensive immunosuppressive therapy, two patients died from complications related to prolonged immunosuppression and the surviving patient experienced persistent visual deficits. Optochiasmatic arachnoiditis represents a rare but catastrophic paradoxical complication of tuberculous meningitis in HIV-negative patients. Improved understanding of the underlying immunopathology is essential to guide targeted adjunctive therapies and improve outcomes.