Mechanical Thrombectomy for Acute Middle Cerebral Artery Occlusion Caused by a Giant, Thrombosed, Extracranial Internal Carotid Artery Aneurysm

Dear Editor, A 45-year-old man was transferred to our stroke unit due to acute right-sided weakness, right hemianopsia, and global aphasia at 390 min after symptom onset [National Institutes of Health Stroke Scale (NIHSS) score=20]. Computed tomography (CT) angiography (CTA) performed at another institution revealed occlusion of the left proximal middle cerebral artery (MCA) due a giant aneurysm of the ipsilateral cervical internal carotid artery (ICA). The second CT and CTA performed at our institution at 405 min after symptom onset showed two small hypodense areas within the left MCA territory [Alberta Stroke Program Early CT score (ASPECTS) score=8/10] as well a large extracranial aneurysm of the left ICA with arterial wall calcification and hypodense material within the lumen corresponding to an intraluminal thrombus (Fig. 1A and B). His neurological status deteriorated further (NIHSS score=23) at 410 minutes after symptom onset. The patient did not fulfill two of the suggested inclusion criteria for mechanical thrombectomy (MT) in acute ischemic stroke (AIS) according to recent recommendations1 (pretreatment with intravenous thrombolysis and time window of ≤6 hours from symptom onset), and the pathology of the extracranial ICA was a contraindication in some of recent randomized controlled trials.2 However, we decided to pursue rescue MT at 415 minutes after symptom onset based on the high ASPECTS score in the second brain CT (8/10), good collaterals in CTA, and the presence of a severe neurological deficit at baseline with further neurological deterioration. Digital-subtraction angiography revealed left proximal MCA occlusion and verified the presence of a giant, partially thrombosed aneurysm in the left ICA (Fig. 1C and D). MT was performed using a triaxial homocentric system approach with placement of a long sheath (Neuron-MAX-6F, Penumra, Alemeda, CA, USA) in the left ICA bulb and distal catheterization of the cavernous ICA through the extracranial aneurysm with a Penumbra 5Max-ACE device and a microcatheter (Rebar-18, Covidien, Dublin, Ireland). Left proximal MCA revascularization was successful with two passages of a Solitaire-FR stent retriever (Covidien) that resulted in substantial thrombus removal (Fig. 1E and F). The procedure took 35 minutes under conscious sedation and resulted in complete reperfusion of the left MCA territory at 455 minutes after symptom onset (Thrombolysis In Cerebral Infarction grade=III). The patient exhibited significant improvement immediately after the procedure, with a NIHSS score of 14 at 460 min after symptom onset. Brain MRI performed after 24 hours (Fig. 1G and H) showed an acute left putaminal infarction with asymptomatic hemorrhagic transformation (hemorrhagic infarct grade=II), while transcranial Doppler ultrasonography showed sustained complete recanalization (TIBI grade=5). The patient experienced further neurological improvement during hospitalization, with mild Odysseas Kargiotis Georgios Magoufis Apostolos Safouris Aristeidis H. Katsanos Eleftherios Stamboulis Georgios Tsivgoulis