EC-IC (Extracranial-Intracranial) bypass surgery is a specialized neurosurgical procedure that restores adequate blood flow to the brain. It creates a new pathway for blood to circumvent narrowed or blocked arteries, preventing serious neurological complications from insufficient blood supply.
Understanding EC-IC Bypass
EC-IC bypass connects an artery outside the skull (extracranial) to an artery inside the skull (intracranial). This reroutes blood flow, providing a reliable source to brain areas not receiving enough, thereby preventing damage from ischemia.
The most common type is the superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. The STA is a vessel in the scalp, and the MCA is a major artery on the brain’s surface. Surgeons connect these two arteries, creating a new conduit for blood to nourish deprived brain areas.
Conditions Treated by EC-IC Bypass
EC-IC bypass treats specific neurological conditions where the brain’s blood supply is severely compromised. Moyamoya disease is a primary indication, characterized by progressive narrowing of arteries at the base of the brain, particularly the internal carotid arteries. This narrowing can lead to recurrent strokes or transient ischemic attacks (TIAs), and bypass surgery helps compensate for reduced natural blood flow.
The procedure is also considered for complex brain aneurysms untreatable by conventional clipping or endovascular coiling. If the artery feeding the aneurysm needs surgical occlusion, the bypass provides an alternative blood supply. Severe intracranial atherosclerosis, a hardening and narrowing of arteries within the skull, can also cause chronic brain ischemia. When other treatments like medication or angioplasty fail or are unsuitable, EC-IC bypass can augment blood flow and reduce stroke risk.
The EC-IC Bypass Surgical Procedure
The EC-IC bypass procedure begins with patient preparation under general anesthesia. The patient’s head is secured in a skull-fixation device. The hair near the incision site is shaved, and the scalp is prepped with an antiseptic solution.
A neurosurgeon makes an incision in the scalp to locate and prepare the extracranial donor artery, often the superficial temporal artery (STA). A craniotomy is performed to expose the brain and the intracranial recipient artery, typically a branch of the middle cerebral artery (MCA). Under an operating microscope, the surgeon prepares the ends of both arteries.
The anastomosis, or connection, of the two arteries is performed using very fine sutures. Temporary clips are applied to the donor and recipient vessels to momentarily stop blood flow. Once the connection is complete, the clips are removed, and blood flow through the newly created bypass is verified, often using intraoperative angiography. Finally, the skull bone is replaced and secured, and the scalp incision is closed.
Post-Surgery Recovery and Outlook
Immediately following EC-IC bypass surgery, patients are transferred to an intensive care unit (ICU) for close monitoring. This includes continuous assessment of vital signs and neurological status, and pain medication is administered to manage discomfort at the incision site. Patients may have an intravenous line, a urinary catheter, and a drain near the surgical wound.
The hospital stay after a craniotomy for EC-IC bypass can range from five to ten days. During this initial recovery, patients may experience headaches, swelling, and bruising of the face. A CT scan is often performed to check for immediate complications, such as bleeding.
The recovery at home generally takes six to twelve weeks, during which driving and strenuous activities are restricted. Long-term outlook after EC-IC bypass often involves improved blood flow to the brain, which can reduce symptoms like dizziness and headaches, and decrease the risk of future strokes, particularly in Moyamoya disease. Follow-up care with the medical team is important to monitor the bypass and overall neurological health.