Transcranial Color-Coded Duplex Ultrasound for Assessing Cerebrovascular Reserve in Intracranial Dissection with Aneurysm.

Intracranial artery dissection (IAD) is an uncommon cause of cerebral ischemia. It may lead to symptoms due to rupture of subadventitial aneurysms or thromboembolism from subintimal disruption. Severe stenosis may lead to reduced cerebrovascular reserve (CVR). While there are many methods of assessing CVR, we report a case of IAD with hemodynamic complications diagnosed by transcranial color-coded duplex (TCCD) ultrasonography. Our patient is a 38-year-old female who presented with a 2-month history of nausea, then feeling faint whenever she got up suddenly. On the day of admission, she had gotten up to walk, felt nauseous, and the left upper limb felt "funny," after which she lost consciousness. Clinical and neurological examination was normal. Brain magnetic resonance (MR) imaging was normal. MR angiogram and subsequent computed tomography (CT) angiogram showed flow attenuation in the M1 segment of the right middle cerebral artery (RMCA), with a possible flap. Catheter angiography was suggestive of a dissection with 2.7 mm pseudoaneurysm. TCCD showed very high velocities in the RMCA. The Breath-Holding Index (BHI) was 0.56, suggestive of reduced CVR in the RMCA territory. Acetazolamide-enhanced single-photon emission CT showed reduced right frontal CVR. She was given clopidogrel for secondary prevention, and has remained well. BHI as measured by TCCD is a new method for assessing CVR in patients with cerebral ischemia.