Revascularisation surgery for paediatric moyamoya: a review of the literature

The role of and optimal surgical revascularisation technique for paediatric moyamoya syndrome (MMS) are controversial. In this literature review our primary aim was to evaluate the evidence base for the efficacy of surgical revascularisation for the treatment of paediatric MMS. Secondary aims were to estimate the rate of peri-operative complications and to ascertain whether direct or indirect revascularisation techniques resulted in differences in clinical or radiological outcomes. Methods: Papers describing surgical revascularisation and its outcome in the treatment of children with MMS were identified from the OVID Medline database (1966-2004). Only papers in English were reviewed. Data were abstracted using a standardised form. Results: Fifty-seven studies, including data on 1,448 patients, were reviewed. Most were Japanese; 10% were from Western institutions. Indications for revascularisation were described in < 15% of studies and varied between centres. Indirect procedures were most commonly performed (alone in 73% of cases, combined with direct procedures in 23%). The rates of peri-operative stroke and reversible ischaemic events were 4.4 and 6.1% respectively. Out of 1,156 (87%) patients, 1,003 derived symptomatic benefit from surgical revascularisation (complete disappearance or reduction in symptomatic cerebral ischaemia), with no significant difference between the indirect and direct/combined groups. Data on developmental and functional outcomes were limited and of uncertain significance as they were not related to pre-operative status. Good collateral formation was significantly more frequent in the direct/combined group than in the indirect group (chi(2), p < 0.001). Conclusions: Data from the medical literature suggest that surgical revascularisation is a safe intervention for paediatric MMS and most treated patients derive some symptomatic benefit. However, paucity of data on selection criteria and more global outcome measures means that the impact of surgical revascularisation on natural history remains uncertain. Direct and/or combined procedures provide better revascularisation, but this is not associated with differences in symptomatic outcome. International standardisation of the clinical approach to the treatment of paediatric MMS is urgently needed to critically evaluate the optimal indications for and timing of surgical revascularisation.