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Published on: May 9, 2013
Improved cerebrovascular reactivity following low flow EC/IC bypass in patients with occlusive carotid disease
Hiren C Patel1, Iain R McNamara, Pippa G Al-Rawi
1University Department of Neurosurgery, Addenbrooke's Hospital, Cambridge, UK.
Insights
Low flow extracranial-to-intracranial (EC/IC) bypass surgery significantly improved cerebrovascular reserve (CVR) in patients with symptomatic cerebral ischemia. This intervention reduced stroke risk and improved patient outcomes, demonstrating its therapeutic potential.
Area of Science:
- Neurosurgery
- Vascular Neurology
- Medical Imaging
Background:
- Major cerebral artery occlusive disease can lead to cerebral hypoperfusion and increased stroke risk.
- Extracranial-to-intracranial (EC/IC) bypass is a potential intervention to mitigate this risk.
- Cerebrovascular reserve (CVR) impairment, detectable by xenon computerised tomography (XeCT), indicates risk of hemodynamic ischemia.
Purpose of the Study:
- To evaluate the effect of low-flow EC/IC bypass on CVR in patients experiencing symptomatic cerebral hemodynamic ischemia.
- To assess changes in regional cerebral blood flow (rCBF) and CVR pre- and post-surgery.
Main Methods:
- XeCT with acetazolamide challenge was used to assess CVR in 13 patients with cerebral hypoperfusion.
- Pre- and postoperative rCBF and CVR were measured and compared.
- Statistical analysis included ANOVA and Student's paired t-test (p < 0.05).
Main Results:
- Baseline rCBF was not significantly improved post-bypass.
- A significant improvement in CVR was observed in the symptomatic hemisphere post-operatively (p = 0.015).
- The MCA territory showed the greatest CVR increase (28%, p = 0.0105), with 85% of patients experiencing symptom improvement or stability.
Conclusions:
- Low-flow EC/IC bypass can enhance CVR in patients with symptomatic cerebral ischemia due to occlusive carotid disease.
- The procedure demonstrated high graft patency (93%) and no operative mortality.
- Individualized therapy with careful patient selection and minimized surgical morbidity is crucial for optimal outcomes.
Abstract:
Patients with major cerebral artery occlusive disease can suffer cerebral hypoperfusion and be at an increased risk of future strokes. EC/IC bypass has been shown to reduce this risk. Patients with cerebral hypoperfusion, and who are at risk of haemodynamic ischaemia, can be identified by the use of xenon computerised tomography (XeCT) to demonstrate severe impairment of the cerebrovascular reserve (CVR). We report our series on the effect of low flow EC/IC bypass on CVR in patients with symptomatic cerebral haemodynamic ischaemia. Thirteen patients with clinical and radiological features of cerebral hypoperfusion were assessed with acetazolamide activated XeCT. Pre- and postoperative regional cerebral blood flow (rCBF) and CVR were assessed. The change in CVR from pre- to post surgery was calculated (%CVR). Values were compared using ANOVA and Student's paired t-test. Unless otherwise stated, values are given as mean +/- standard error of the mean. Statistical significance was taken at p < 0.05. Pre-operative symptomatic hemisphere CBF was 38 +/- 2 mls/100g/min compared to 40 +/- 3.2 mls/100 g/min in the asymptomatic hemisphere, with the greatest difference observed in the MCA territory (38.6 +/- 2 cf 45.4 +/- 3.2 mls/100g/min). Baseline CBF was not significantly improved post EC/IC bypass. However CVR was significantly improved in the symptomatic hemisphere post-operatively (p = 0.015), with the greatest increase (28%) seen in the MCA territory (p = 0.0105). First, 85% of patients had either an improvement in symptoms or no further symptoms. There was a 93% graft patency and no operative mortality. Low flow EC/IC bypass can improve CVR in patients with symptomatic cerebral ischaemia in the presence of occlusive carotid disease. However, therapy must be individualised, with careful patient selection and minimal surgical morbidity.
