This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: https://info.ahrq.gov. Let us know the nature of the problem, the Web address of what you want, and your contact information.
Please go to www.ahrq.gov for current information.
Title: Extracranial-Intracranial Bypass To Reduce the Risk of Ischemic Stroke
Agency: Agency for Health Care Policy and Research/Center for Health Care Technology
(formerly the Office of Health Technology Assessment)
Contact: Thomas V. Holohan, M.D.
Status: Technology Assessment: Published, 1990
Primary Objective: To evaluate the safety, efficacy, and clinical effectiveness of extracranial-intracranial bypass to prevent stroke.
Methods used: Review of published medical literature.
Data identification: Published articles in the English language. A MEDLINE search of the
National Library of Medicine using search terms "extracranial-intracranial bypass" and "stroke"
was completed; information was also solicited from other agencies of the Public Health Service. A
Federal Register notice was also published soliciting information from the medical community at
Study Selection: Published articles which addressed the issue of the effectiveness of EC-IC
bypass in the prevention of stroke were selected. Thirteen case series encompassing 1,464 patients
and one prospective, randomized control trial of 1,377 patients were found.
Data extraction: Type of study, sample size, patient selection criteria, controls (historical or
randomized), comparison of outcomes of operated patients versus historical or randomized
Key findings: The surgical case series provided insufficient information to precisely characterize
the operated patients, and most contained inadequate data for followup determination of the
frequency of postoperative stroke; the historical annual stroke rates to which the operated cases
were compared varied between 3% and 25%, and the concomitant effect of antiplatelet drugs was
not addressed. Operative stroke and mortality rates did not differ from those in the prospective
trial. The multicenter cooperative randomized trial demonstrated that at 56 months of followup
the annualized stroke rates were 6.2% for medically treated patients and 6.6% for operated
Conclusions: There are no reliable objective data which indicate that there exists a group of
patients in whom EC-IC bypass reduces the rate of stroke compared to patients managed
medically. The results of the single prospective randomized trial must be accepted as the best
medical evidence currently available.