Meningococcal Meningitis Complicated by Cerebral Venous Sinus Thrombosis Presenting as Pseudo-Subarachnoid Hemorrhage in a Toddler: A Case Report.

Cerebral venous sinus thrombosis (CVST) is a rare and potentially devastating complication of bacterial meningitis. While a small number of adult cases have been reported, meningococcal-associated CVST in children is exceptionally rare. We report a previously healthy 20-month-old boy who presented with fever, vomiting, irritability, and a left convergent squint. Initial non-contrast computed tomography of the brain demonstrated bilateral tentorial hyperdensities consistent with the pseudo-subarachnoid hemorrhage sign, an imaging pitfall in which venous engorgement and cerebral edema mimic true subarachnoid hemorrhage. Subsequent magnetic resonance venography and computed tomography venography confirmed acute thrombosis of the right transverse and sigmoid sinuses. Cerebrospinal fluid polymerase chain reaction obtained on the third day of admission confirmed Neisseria meningitidis. The patient was treated with appropriate antimicrobial therapy, intensive supportive care, and therapeutic anticoagulation with enoxaparin, achieving progressive clinical improvement without hemorrhagic complications. Thrombophilia workup, including complement levels, immunoglobulins, protein C, protein S, and antithrombin III, was unremarkable. To the best of our knowledge, this represents the first reported case of meningococcal meningitis complicated by CVST in a child without an identified thrombophilic predisposition, suggesting that meningococcal infection alone may be sufficient to precipitate CVST. This case underscores the importance of maintaining a high index of suspicion for CVST, recognizing the pseudo-subarachnoid hemorrhage sign as a potential diagnostic pitfall, and pursuing early venographic imaging when neurological deterioration occurs despite appropriate antimicrobial therapy.