Transient Ischemic Attack Progressing to Top-of-the-Basilar Syndrome: A Case Report

BACKGROUND Top-of-the-basilar syndrome (TOBS) is a rare but clinically heterogeneous posterior circulation disorder characterized by acute ischemia affecting 2 or more territories supplied by the distal basilar artery, including the thalami, midbrain, occipital lobes, medial temporal lobes, and cerebellum. Intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) is an established treatment for eligible patients with TOBS, and reports of transient coma induced during rt-PA infusion remain exceedingly scarce. CASE REPORT A 77-year-old man with non-valvular atrial fibrillation and hypertension presented with transient visual hallucinations-initially diagnosed as a transient ischemic attack. Emergency head and neck computed tomography angiography revealed severe stenosis-occlusion of the left posterior cerebral artery P1 segment. Within 12 hours, he developed dysarthria and right hemiparesis, prompting intravenous thrombolysis with rt-PA (0.9 mg/kg). Fifty minutes after infusion, he experienced abrupt, self-limiting loss of consciousness, without evidence of intracranial hemorrhage on emergent computed tomography. Subsequent magnetic resonance imaging confirmed incomplete TOBS, showing acute infarcts in bilateral thalami, left hippocampus, and right cerebellar hemisphere. Magnetic resoance angiography demonstrated resolution of the prior P1 stenosis but new suspicious narrowing in the distal P2 segment. CONCLUSIONS This case suggests that the clinical symptoms of cardiogenic TOBS change rapidly and are diverse. This diversity can occur before and during intravenous thrombolytic therapy. If neurological deterioration occurs during the use of thrombolytic agents, it is necessary to promptly identify whether it is stroke progression or hemorrhagic transformation.