Clinical StudySTA–MCA bypass for symptomatic carotid occlusion and haemodynamic impairment
Introduction
There is a group of patients with symptomatic carotid occlusion in whom the symptoms and imaging findings suggest a haemodynamic rather than embolic cause of ischemia. Prospective studies of such patients report that those with impaired haemodynamics have an annual risk of stroke of between 8% and 36% which is significantly higher than in patients with normal haemodynamics (0–6%).[1], [2], [3], [4], [5], [6], [7], [8] In these patients, improving the cerebral blood supply by an external to internal carotid artery bypass (EC–IC bypass) improves the haemodynamic reserve.[9], [10], [11], [12] Bypass surgery remains controversial, however, because a clinical benefit has not been proven.
We describe the clinical presentation, management and outcome of 19 patients who underwent EC–IC bypass for symptomatic carotid occlusion and impaired cerebrovascular reserve (CVR), detected by single photon emission computed tomography (SPECT) and acetazolamide challenge.
Section snippets
Patient characteristics and clinical management
From January 2000 to January 2006, 31 patients were referred for consideration of bypass surgery. Five patients had symptomatic carotid occlusion but did not have significant acetazolamide-induced perfusion reduction. Three patients were seen with abnormal SPECT scans but unclear symptomatology. These patients were not offered surgery. Twenty-two patients presented with symptomatic carotid occlusion and haemodynamic compromise detected by SPECT scan. Eighteen of these patients underwent
Patient 13
This 50-year-old man presented with a left hemiparesis due to cerebral infarction. Carotid angiography demonstrated occlusion of the right internal carotid artery (ICA) secondary to dissection, intracavernous stenosis of the left ICA, and poor collateral circulation (Fig. 2). MRI demonstrated an internal watershed pattern of ischemia consistent with haemodynamic rather than embolic pathology and the SPECT scan demonstrated right hemispheric steal (Fig. 1). A right STA–MCA anastomosis was
Discussion
In patients with symptomatic carotid occlusion and impaired haemodynamic reserve the stroke rate per year with medical management alone is about 18% (Table 2) compared to about a 3% yearly risk in patients with normal haemodynamics. In our patient series, there were four post-operative strokes in 52 years of patient follow-up, for an annual risk of stroke of 7.6%.
In spite of not having a true control group, we are still able to compare our patients with others. During the time on the waiting
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