Burnt-out arteriovenous malformation mimicking unilateral Fahr’s disease: a diagnostic pitfall in adult-onset seizure: a case report

Background

Intracranial calcifications are a common radiological finding, but their significance varies widely depending on the pattern and distribution. While Fahr's disease is often considered in such cases, it typically presents with bilateral and symmetrical involvement. Unilateral, extensive calcifications, especially when associated with cerebral atrophy, should prompt a broader differential. Case Presentation: We describe a 43-year-old man with no significant medical history who presented with his first-ever seizure. He was found unresponsive by his wife, with tongue biting and post-ictal confusion. By the time he arrived in the emergency department, he had returned to baseline, and his neurological examination was completely normal. Initial CT imaging revealed extensive right-sided subcortical calcifications with associated cerebral atrophy, raising the possibility of Fahr’s syndrome. However, further imaging told a different story. MRI indicated dilated convoluted signal-void formations with post-contrast enhancement, and SWI confirmed widespread blooming matching the calcifications. At the right MCA bifurcation, CT angiography revealed a 4.1 mm focal dilatation with surrounding tortuous arteries. Ultimately, digital subtraction angiography did not demonstrate an active AVM but did reveal an ectatic MCA bifurcation with a small aneurysmal bulge. Taken together, the findings were most consistent with chronic changes from a previously existing, now regressed vascular malformation.