Bilateral thalamic lesions are an uncommon presentation that can arise from various etiologies. This case report discusses a unique instance of bilateral thalamic ischemia caused by an arteriovenous fistula (AVF).

A 64-year-old man with hypertension, hyperlipidemia, and type 2 diabetes mellitus presented to the emergency department after being found confused by a neighbor. Prior to this presentation, he was fully independent in all his activates of daily living and was working as a full-time taxi driver. In the week before his presentation, patient was treated with amoxicillin by his primary care provider for fevers and chills. Neurological assessment revealed significant cognitive deficits in attention, executive function and memory. Further, the patient exhibited a tearful affect and cried multiple times during the interview. Given his recent fevers, he was empirically started on meningitis coverage until a negative lumbar puncture resulted. Initial CT head revealed hypodense changes suggesting ischemia in the left corona radiata and internal capsule, alongside chronic lacunar infarcts in both thalami which on MRI was more suspicious for hemorrhagic necrosis of bilateral thalami from possible deep cerebral vein thrombosis. CT angiography was performed which demonstrated abnormal opacification of deep cerebral veins, raising suspicion for an underlying vascular malformation. This was confirmed on digital subtraction angiography showing a dural AVF with branches from the occipital artery feeding into the vein of Galen which was successfully treated through endovascular coil embolization. Post-intervention imaging demonstrated reduced edema in the thalami, indicating improved venous drainage. The patient was discharged on anticoagulation therapy with significant cognitive improvement and complete resolution to his functional baseline.

This is a uncommon case of an AVF leading to bilateral thalamic lesions, underscoring the importance of considering vascular etiologies in similar presentations. Recognizing these rare associations can lead to timely and effective interventions, improving patient outcomes.