# ’Carotid spells’ - transient focal neurological episodes associated with convexity subarachnoid haemorrhage in severe ipsilateral extracranial internal carotid artery stenosis: a case report and concise literature review

## TL;DR

A rare case links carotid artery stenosis to subarachnoid hemorrhage and transient neurological episodes, suggesting a new clinical connection.

## Contribution

Identifies extracranial carotid stenosis as a potential cause of convexity subarachnoid hemorrhage and transient neurological episodes.

## Key findings

- A 46-year-old patient with carotid stenosis presented with cSAH and TFNEs.
- Empirical antiepileptics and endarterectomy led to symptom resolution.
- cSAH may result from fragile collaterals in severe carotid stenosis.

## Abstract

Convexity subarachnoid haemorrhage (cSAH) is most frequently caused by cerebral amyloid angiopathy (CAA), often presenting with transient focal neurological episodes (TFNEs, a.k.a. amyloid spells). In younger patients, posterior reversible encephalopathy, reversible cerebral vasoconstriction syndrome, and sinus thrombosis are the most frequent aetiologies. Reports on extracranial internal carotid artery (ICA) stenosis-associated cSAHs are exceptional.

A 46-year-old female with a history of heavy smoking presented with repetitive stereotypical right-sided sensory TFNEs. An acute cranial computed tomography revealed multi-lobar left hemispheric cSAHs. The angiography demonstrated severe bilateral extracranial atherosclerotic ICA stenosis with left-sided predominance and no intracranial involvement. In addition to confirming the cSAHs, a magnetic resonance imaging revealed acute/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, in addition to repetitive transient ischaemic attacks secondary to stenosis, focal epileptic or spell-like episodes triggered by the cSAHs were considered as plausible mechanisms underlying the TFNEs. Given the high TFNE frequency on admission, empirical antiepileptics were initiated; the patient subsequently became asymptomatic and the TFNEs stopped. Secondary stroke prevention was initiated on day 9. Considering the asymptomatic state and the recent intracranial haemorrhages, vascular surgeons opted for elective endarterectomy of the left ICA, which was performed 6 weeks later. The contralateral endarterectomy was performed three months later. The patient is asymptomatic and the antiepileptics have been successfully tapered. We propose that, in our case, cSAHs could be attributed to severe ipsilateral ICA stenosis and consequently recruited fragile leptomeningeal collaterals, similarly to that seen in moyamoya disease/syndrome. The TFNEs most likely developed secondary to a cSAH-associated mechanism reminiscent of that seen in amyloid spells in CAA.

cSAH is a rare but often symptomatic manifestation of an ipsilateral significant extracranial ICA stenosis, which widens the spectrum of its possible clinical manifestations. Expanding the literature of the few cases previously reported with a similar scenario, our case draws attention to the significance of extracranial vascular imaging in the setting of TFNEs and/or cSAHs, to promote the timely diagnosis of stenotic alterations of potential surgical relevance.