Rituximab induced cerebral venous sinus thrombosis in a patient with anti-N-methyl-D-aspartate receptor-antibody encephalitis: a case report and review of literature.

Background: Cerebral venous sinus thrombosis has not been reported in anti-N-methyl-D-aspartate receptor-antibody encephalitis in the absence of an underlying thrombotic state while rituximab induced cerebral venous sinus thrombosis is rarely reported. We report a patient with anti-N-methyl-D-aspartate receptor-antibody encephalitis without a prothrombotic state who developed cerebral venous sinus thrombosis following rituximab treatment.

Case presentation: A 15-year-old Sri Lankan girl who had been in remission following an episode of anti-N-methyl-D-aspartate receptor-antibody encephalitis 2 years ago, presented with a relapse of anti-N-methyl-D-aspartate receptor-antibody encephalitis characterized by recurrent seizures, mutism, and cognitive abnormalities. Since response was inadequate to first-line immunotherapy, she was administered four doses of rituximab at weekly intervals. Two days after the fourth dose, she developed increasing headaches, and her cranial magnetic resonance venogram confirmed the development of cerebral venous sinus thrombosis. Screening for prothrombotic states were negative. She made an unremarkable recovery following anticoagulation.

Conclusion: This case highlights the occurrence of the rare but serious complication of cerebral venous sinus thrombosis following rituximab in the context of anti-N-methyl-D-aspartate receptor-antibody encephalitis and informs the clinician to be wary of new onset headache in patients with anti-N-methyl-D-aspartate receptor-antibody encephalitis treated with immunotherapy.