¹ Division of Clinical Neurosciences, Western General Hospital, Edinburgh, UK
² Department of Clinical and Surgical Sciences (Geriatric Medicine), Royal Infirmary of Edinburgh, Edinburgh, UK

Correspondence to:
Correspondence to:
Professor J M Wardlaw
Department of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK; jmw{at}skull.dcn.ed.ac.uk

Background/Aim: The neurological effects of internal carotid artery (ICA) occlusion vary between patients. The authors investigated whether the severity of symptoms in a large group of patients with ipsilateral or/and contralateral ICA occlusion at presentation with ocular or cerebral ischaemic symptoms could be explained by patency of other extra or intracranial arteries to act as collateral pathways.

Methods: The authors prospectively identified all patients (n = 2881) with stroke, cerebral transient ischaemic attack (TIA), retinal artery occlusion (RAO), and amaurosis fugax (AFx) presenting to our hospital over five years, obtained detailed history and examination, and examined the intra and extracranial arteries with carotid and colour-power transcranial Doppler ultrasound. For this analysis, all those with intracranial haemorrhage on brain imaging and cerebral events without brain imaging were excluded.

Results: Among 2228/2397 patients with brain imaging (1713 ischaemic strokes, 401 cerebral TIAs, 193 AFx, and 90 RAO) who underwent carotid Doppler, 195 (9%) had ICA occlusion. Among those patients with cortical events, disease in potential collateral arteries (contralateral ICA, external carotid, ipsilateral or contralateral vertebral or intracranial arteries) was equally distributed among patients with severe and mild ischaemic presenting symptoms.

Conclusion: The authors found no evidence that the clinical presentation associated with an ICA occlusion was related to patency of other extra or intracranial arteries to act as collateral pathways. Further work is required to investigate what determines the clinical effects of ICA occlusion.

Abbreviations: ACA, anterior cerebral artery; ACoA, anterior communicating artery; AFx, amaurosis fugax; CCA, common carotid artery; ECA, external carotid artery; ICA, internal carotid artery; LACI, lacunar infarct; MCA, middle cerebral artery; OCSP, Oxfordshire Community Stroke Project; PACI, partial anterior circulation infarct; PCoA, posterior communication artery; POCI, posterior circulation infarct; RAO, retinal artery occlusion; TACI, total anterior circulation infarct; TIA, transient ischaemic attack

Keywords: carotid occlusion; carotid Doppler; collateral circulation; ischaemic stroke; transient ischaemic attacks