Abstract Number: Esoc2026a824 ’carotid Spells’ - Transient Focal Neurological Episodes Related to Convexity Subarachnoid Haemorrhage Caused by Severe Ipsilateral Extracranial Internal Carotid Artery Stenosis: Case Report

Abstract Background and aims Convexity subarachnoid haemorrhage (cSAH) is most frequently caused by CAA, often presenting with transient focal neurological episodes (TFNEs, amyloid spells). In younger patients, PRES, RCVS, and sinus thrombosis are the most frequent aetiologies. Reports on ICA stenosis-related cSAHs are exceptional. Methods We present a single-patient case report. Clinical data were collected from medical records, including history, physical examination, laboratory tests and imaging studies. Comprehensive review of the literature was conducted focusing on similar reported cases. Written informed consent was obtained from the patient. Results A 46-year-old female presented with repetitive stereotypical right-sided sensory TFNEs. Cranial CT revealed multi-lobar left hemispheric cSAHs. The angiography demonstrated severe bilateral extracranial atherosclerotic ICA stenosis and no intracranial involvement. In addition to confirming the cSAHs, a MRI revealed subacute small ischaemic alterations in the left anterior watershed area. A detailed diagnostic work-up did not reveal an alternative aetiology. Based on the stereotyped presentation, repetitive TIAs, focal epileptic or spell-like episodes triggered by the cSAHs were considered as mechanisms. Empirical antiepileptics were initiated. Considering the asymptomatic state vascular surgeons opted for elective endarterectomy of the left ICA. In our case, the cSAHs were attributed to ICA stenosis and consequently recruited fragile leptomeningeal collaterals. The TNFEs most likely developed secondary to cSAH-associated mechanism. Conclusions cSAH is a rare manifestation of an ipsilateral significant extracranial ICA stenosis, which widens the spectrum of its possible clinical manifestations. Our case draws attention to the significance of extracranial vascular imaging in the setting of TFNEs and cSAHs, to promote the timely diagnosis. Conflict of interest Levente Szalárdy: received speakers’ and advisory board honoraria from Biogen, speakers’ and authors’ honoraria from Viatris unrelated to the present content, a scientific award from Gedeon Richter Plc., and conference registration fees from Bayer, Biogen, Gedeon Richter Plc., Sandoz, Sanofi-Genzyme, and Viatris. József Norbert Nemes: nothing to disclose. Péter Klivényi: nothing to disclose. Emil Ferencz: nothing to disclose