Peer-Review ReportIndications and Results of Direct Cerebral Revascularization in the Modern Era
Introduction
Microvascular bypass surgery was introduced by Yaşargil in 1970 (30) and rapidly became a mainstay in the treatment of patients with intracranial ischemia. However, improvements in medical management and the publication of results from the extracranial-intracranial (EC-IC) bypass trial and subsequent Carotid Occlusion Surgery Study trial have dampened enthusiasm for the use of bypasses for intracranial ischemias 2, 23. At the same time, advances in chemotherapy combined with better and more precise radiation techniques have reduced the use of cerebral revascularization for treating complex skull base tumors (15). The introduction and refinement of endovascular techniques that began in the 1990s also led to a decrease in the use of bypass techniques for giant and complex aneurysms, where revascularization and trapping was once the definitive treatment 14, 16, 17, 18.
Cerebral revascularization remains the primary treatment in certain neurovascular diseases, such as moyamoya angiopathy, but these cases are uncommon, and patients are rarely treated outside of major tertiary care centers 4, 7, 13, 27. The changes in the aforementioned practice paradigms outlined and the decrease in the use of bypass techniques beget 2 important and related questions: What are the current indications for cerebral revascularization? With a decreasing number of bypass procedures being performed, do the results of microvascular bypass surgery remain comparable to historical controls?
To address these questions, we retrospectively reviewed all direct cerebral revascularization procedures performed at our center in the modern endovascular era (2006−2013) to evaluate indications for their use and the outcome of patients, with special emphasis on the rates of morbidity and mortality associated with the use of bypass.
Section snippets
Patient Population
Between January 2006 and March 2013, 121 consecutive patients underwent direct microsurgical cerebral revascularization alone or in combination with other procedures. Patients with penetrating intracranial trauma were excluded from this analysis. Medical records, neurological examinations, and radiographic studies were reviewed retrospectively. Pre- and postoperative neurological function was evaluated via Glasgow Outcome Scale (GOS) scores. Patients undergoing cerebral revascularization in
Results
Altogether, 121 patients (75 female, 46 male) with a mean age of 46.6 years (range, 1−87 years) underwent 131 direct cerebral revascularization procedures. The indications for revascularization and overall patient characteristics are summarized in Table 1. In total we performed 47 (35.9%) revascularization procedures for 40 patients with moyamoya disease, 56 (42.7%) procedures for 54 patients with complex aneurysms, and 28 (21.4%) procedures for 27 patients with occlusive vascular disease
Discussion
Advances in the medical management of patients with cerebral ischemia, targeted therapies for malignancies, and expanding endovascular techniques have resulted in a significant decrease in the indications for microvascular cerebral revascularization. As an example, we previously reported the results of our experience in 18 patients who underwent carotid artery occlusion and bypass for malignancies involving the skull base (15). In contrast to this previous report, we did not perform a single
Conclusion
The introduction of more effective medical therapies, targeted chemotherapeutics and novel radiation, and endovascular techniques has changed the traditional paradigm of and indications for cerebral revascularization. Whereas bypass surgery has been used since its inception as a mainstay for treating intracranial occlusive disease and was widely used as an adjunct in the treatment of skull base tumors and aneurysms, the numbers of cases in which these techniques are still used are diminishing.
References (30)
- et al.
Further conclusions from the extracranial-intracranial bypass trial
Surg Neurol
(1986) - et al.
The extracranial-intracranial bypass study
Surg Neurol
(1986) - et al.
Endovascular treatment for moyamoya disease in a Caucasian twin with angioplasty and Wingspan stent
Clin Neurol Neurosurg
(2009) Extracranial to intracranial bypass and the prevention of stroke
Lancet
(1985)Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke. Results of an international randomized trial. The EC/IC Bypass Study Group
N Engl J Med
(1985)The EC/IC Bypass Study group. The International Cooperative Study of Extracranial/Intracranial Arterial Anastomosis (EC/IC Bypass Study): methodology and entry characteristics
Stroke
(1985)- et al.
Surgical outcomes for moyamoya angiopathy at barrow neurological institute with comparison of adult indirect encephaloduroarteriosynangiosis bypass, adult direct superficial temporal artery-to-middle cerebral artery bypass, and pediatric bypass: 154 revascularization surgeries in 140 affected hemispheres
Neurosurgery
(2013) - et al.
Extracranial-intracranial bypass surgery: a critical analysis in light of the International Cooperative Study
Neurosurgery
(1986) - et al.
Estimating the proportion of intracranial aneurysms likely to be amenable to treatment with the pipeline embolization device
J Neurointerv Surg
(2013) - et al.
Intracranial carotid artery stent placement causes delayed severe intracranial hemorrhage in a patient with moyamoya disease
J Neurointerv Surg
(2011)