2026 Poster Presentations
P494: INDIRECT EXTRACRANIAL-INTRACRANIAL BYPASS IS A VALID SURGICAL OPTION FOR NON-MOYAMOYA ATHEROSCLEROTIC CAROTID OCCLUSION: ILLUSTRATIVE CASE
Armando Bunjaj, BS; Alexandra Abrams, BS; Edinson Najera, MD, FCNS; Ralph Rahme, MD, FACS, FCNS; SBH Health System
While indirect extracranial-intracranial (EC-IC) bypass, particularly encephaloduroarteriosynangiosis (EDAS), is an established and effective treatment for moyamoya, its role in atherosclerotic carotid occlusion remains unclear, due to limited neoangiogenesis in adults. We present angiographic evidence of successful, robust neoangiogenesis following rescue EDAS in a patient with non-moyamoya carotid occlusion, after a failed attempt at direct EC-IC bypass.
A 58-year-old man, heavy smoker with multiple cardiovascular risk factors (diabetes, hypertension, coronary artery disease), presented with a 1-year history of recurrent transient ischemic attacks and strokes in the right cerebral hemisphere, despite maximal medical therapy (antiplatelet agents, statin). Neurologic exam revealed mild left brachiofacial hemiparesis and a modified Rankin scale (mRS) score of 2. Brain imaging (CT, MRI) showed multiple small, acute and chronic, right cerebral hemispheric infarcts with a watershed distribution. Cerebrovascular imaging (CTA, DSA) revealed multifocal extracranial and intracranial atherosclerotic disease, including an occluded right internal carotid artery (ICA) at its origin in the neck, with limited circle of Willis and leptomeningeal collaterals (insufficient anterior communicating artery, fetal posterior cerebral arteries), and distal reconstitution of the cavernous and supraclinoid segments of the right ICA via internal maxillary-ethmoidal-ophthalmic collaterals. Brain SPECT without and with acetazolamide confirmed the presence of reduced cerebrovascular reserve in the right MCA territory. Thus, surgical cerebral revascularization via a direct EC-IC bypass was offered, consisting of a superficial temporal artery (STA)-middle cerebral artery (MCA) end-to-end anastomosis, using the parietal branch of the STA. Although this was attempted intraoperatively, the surgical plan for a direct bypass had to be abandoned because of a small STA caliber and poor recipient vessel quality, precluding a successful anastomosis. Thus, an indirect EDAS procedure was performed, making use of the already harvested parietal branch of the STA. The patient had an initially uneventful postoperative course, remaining neurologically unchanged. However, three days later, following an inadvertent hypotensive episode (overdose on antihypertensive medications), he developed a sizable right MCA territory infarct with a dense left brachiofacial hemiparesis. The patient was ultimately transferred to a rehabilitation facility, where he exhibited gradual improvement in his neurologic exam and functional performance. Remarkably, however, the patient’s recurrent ischemic events rapidly subsided over time and, by the end of the first month after surgery, had largely resolved. At his one year follow-up appointment, the patient continued to exhibit a moderate left brachiofacial hemiparesis with a mRS score of 3. Repeat cerebral DSA, 6 months and 1 year postoperatively, demonstrated excellent revascularization of the right MCA territory via the EDAS bypass, with the development of rich EC-IC collaterals arising from the parietal branch of the STA and the middle meningeal artery (Matsushima grade A).
Contrary to traditional belief, indirect cerebral bypass, particularly EDAS, remains an effective surgical revascularization strategy in patients with non-moyamoya atherosclerotic carotid occlusion for whom a direct bypass strategy is not feasible or unsuccessful. Evidently, effective revascularization and collateralization following indirect EC-IC bypass is a time-dependent process, necessitating weeks to months to mature, during which the patient is potentially vulnerable to recurrent ischemic events.