Moyamoya disease (MMD) is a progressive occlusive disease of the distal internal carotid arteries associated with secondary stenosis of the circle of Willis 1. Patients with MMD differ from those with normal cerebral blood vessels due to unstable intracranial artery hemodynamics and poor blood flow reserve 2. Hence, perioperative risk factors, intraoperative techniques, and anesthesia can affect the hemodynamics of these patients 2,3. When the brain cannot tolerate high blood flow rate due to long term ischemia, it becomes prone to hyper perfusion syndrome 4. This eventually leads to local neuro-functional deficit, and in more serious circumstances can cause life-threatening intracranial hemorrhage 5. Similarly, these fragile cerebral blood vessels with impaired cerebrovascular regulation have tendency for post-operative infarction and hemorrhage involving the asymptomatic cerebral hemisphere as well 6. One previous study 7 has also reported acute brain swelling intraoperatively due to anesthesia.
Keeping in mind the vascular pathology behind MMD, we need to be cautious in the operative techniques. During neurosurgical procedures, Mayfield skull clamp is the most commonly used 3-pin head immobilization device.
Mayfield skull pins are placed in the latitude line that corresponds with the linea temporalis, hence the occipital artery and temporalis muscle might get trapped while pin placement 8. The superficial temporal artery (STA) penetrate through the temporalis muscle, and there is higher likelihood of development of temporary ischemia in the cerebral cortex upon widely opening the temporalis muscle mouth and/or if excessive pressure is applied on the muscle during clamp placement. That said, there are higher chances of bypass occlusions in the absence of sufficient collateral circulation or combined indirect revascularization.
Therefore, we introduce the use of gel rolls instead of Mayfield skull clamp to avoid risk of vascular compromise and achieve an excellent clinical outcome. This is a conceptual framework in understanding the use of gel roll to avoid serious complications due to Mayfield clamp. (Fig. 1) The patients were positioned supine on the operative table after induction of anesthesia. Patients heads were placed on gel roll and turned to the side opposite to the site of surgery. No changes in SSEP or EEG recordings were noted during the course of surgery. None of the patients had any postoperative complications.
50-year-old female with history of severe right carotid stenosis and strokes. She ended up having an attempt at opening up the carotid, which resulted in occlusion. She was receiving all of her right hemisphere blood supply through the anterior communicating artery. She continued to have watershed strokes on the right side. Therefore, STA to middle cerebral artery (MCA) bypass was carried out.
31-year-old female with history of MMD and bilateral frontal stroke secondary to hypoperfusion. Perfusion imaging revealed the penumbra/hypoperfusion region to be at risk. Patient underwent direct and indirect STA MCA bypass followed by revision right-sided indirect STA MCA bypass [encephaloduroarteriosynangiosis (EDAS)].
56-year-old female with a history of intermittent left sided hemiparesis underwent indirect STA to MCA bypass.
42-year-old male with a history of left M1 occlusion presented with proliferation of MMD diagnosed on digital subtraction angiography (DSA). Left indirect STA to MCA bypass was performed [EDAS]
37-year-old female with bilateral MMD presented with occlusion of internal carotid artery terminus on the left side. She had bilateral watershed infarcts on maximal medical therapy. She underwent direct STA MCA bypass on the left side followed by right-sided indirect STA MCA bypass [EDAS].
Various complications can occur in MMD revascularization procedure due to sudden increase in cerebral blood flow or hemodynamic changes caused by perioperative factors. Hence, the use of gel rolls over the Mayfield skull clamp during surgery must be considered as this can help in avoiding the risk factors of vascular compromise such as compression of temporalis muscle, traumatic aneurysm, and vascular resistance. Nonetheless, the use of gel roll in our patients have suggested that it improves the outcomes for patients. Randomized controlled trial comparing the gel roll versus the Mayfield skull clamp may better define the most appropriate indications and use of these procedures.