Moyamoya disease is one that draws initial attention for neurologists due its intriguing name. “Puff of smoke” in Japanese, the disease is named after the angiographic appearance that patients with the condition have due to development of tiny collateral vessels to compensate for large artery stenosis usually occurring in bilateral ICAs, extending to the MCAs and ACAs. Revascularization procedures in the illness such as superficial temporal artery- middle cerebral artery (STA-MCA) bypass procedure and dural synangiosis have been used to improve collateral flow and appear to benefit patients in overall outcome. Usually patients are assigned to one type of bypass technique however the authors out of Korea attempted to combine the procedures of STA-MCA anastomosis and encephalodurogaleosynangiosis (EDGS) and see if these improved long term outcome in adult Moyamoya disease.
The group performed STA-MCA bypass and EDGS on 77 hemisphere in 60 patients and followed the patients for short-term (approx. 6 months) and long-term (approx.. 5 year) periods and compared clinical status improvement based on Karnofsky Performance Scale (KPS) and modified Rankin Scale (mRS) measures. All procedures were performed by a single surgeon. They also quantitatively measured the revascularization area relative to the supratentorial area by using cerebral angiography as well as used SPECT scans with and without acetazolamide to be able to assess hemodynamic status for these patients both before and after the procedure. They found that clinical status by KPS and mRS improved from 81.1 (+/- 6.7) and 1.5 +/- 0.6 respectively to 96.2 (+/- 8.4) to 0.4 (+/- 0.7). Symptomatic clinical hyperperfusion syndrome was seen in 29.9% (23 operations, 21 patients). The revascularization area improved from long-term follow up compared to short term (54.8% vs 44.2%, P<0.001). CBF also increased from preoperative values to the short term follow up period (P<0.001) and then became stable. Only 2 hemorrhagic events and 1 infarction were seen during follow up translating to symptomatic hemorrhage and infarction rates of 0.4%/person-year and 0.2%/person-year respectively. No patients died.
The combined revascularization technique makes sense as the STA-MCA bypass would provide immediate cerebral blood flow to the area of need and the EDGS would create more of a long-term benefit with slow forming collaterals over 3-6 months. Because no randomized control trials exist comparing surgical methods, and the inherent difficulties are present in comparing small retrospective trials given different surgical techniques, small number of patients, etc., the Korean group aimed to use a well-designed study to prove their point that this particular method can be used on adults with Moyamoya disease with relatively few complications and good outcomes and it appears they succeeded.