Unmasking Hypercoagulability: Superior Sagittal Sinus Thrombosis Attributed to Pernicious Anemia in a Patient With Normal Hemoglobin Levels.

BACKGROUND Superior sagittal sinus thrombosis is an uncommon but serious cerebrovascular disorder, often linked to a hypercoagulable state. One less common etiology of hypercoagulability is elevated homocysteine levels due to vitamin B12 deficiency caused by pernicious anemia, a process that usually also results in concurrent megaloblastic anemia. We describe a patient who developed superior sagittal sinus thrombosis despite normal hemoglobin and hematocrit values. CASE REPORT A 52-year-old man presented to the emergency department with first-time tonic-clonic seizure. Brain magnetic resonance imaging revealed thrombosis of the superior posterior segment of the superior sagittal sinus. Additional studies demonstrated deep vein thrombosis in the right peroneal vein. Extensive evaluation for potential prothrombotic causes revealed an elevated homocysteine level and vitamin B12 deficiency. The patient had serologic evidence of pernicious anemia; antibodies against intrinsic factor and gastric parietal cells were present. Despite the pernicious anemia diagnosis, his hemoglobin level was normal. High-dose oral vitamin B12 was administered to correct the deficiency and alleviate the hypercoagulable state. The patient was initially anticoagulated with a heparin infusion to treat the superior sagittal sinus thrombosis; therefore, intramuscular injections of vitamin B12 were avoided during hospitalization. He was ultimately discharged home with prescriptions for apixaban and intramuscular injections of vitamin B12. CONCLUSIONS Patients presenting with thrombotic events should be thoroughly evaluated for an underlying hypercoagulable state to ensure appropriate treatment and prevent complications. This case highlights the importance of considering hyperhomocysteinemia induced by vitamin B12 deficiency as a cause of thrombosis, even in patients with normal hemoglobin levels.