LAUSR

Dear Editor, We read with great interest the recent paper by Lavrysen et al. [3] published on Acta Neurochirurgica. The authors provided a description of burr hole surgery, a surgical indirect revascularization procedure used in moyamoya disease (MMD) and moyamoya syndrome (MMS), consisting in burr hole placement over the ischemic cortex, through which periosteal flaps are arranged to reach the surface of the brain.MMS andMMD are characterized by the progressive bilateral occlusion of the internal carotid artery (ICA) and its branches, with secondary formation of anastomotic collateral capillary network on the cortical surface [5, 6]. Their typical presentation is with ischemic attack and transient ischemic attack (TIA) in children and hemorrhages in adults. The rationale of this procedure is that a cortical revascularization can be achieved by connecting the ischemic cortex with periosteal flaps, which are normally supplied by the superficial temporary artery (STA) and the middle meningeal artery (MMA), which are both originating from the external carotid artery, and, for this reason, not involved in MMD and MMS. Particular importance is given by the authors to the burr hole placement over the ischemic cortex, in order to not interfere with the supplying vasculature of one another. Another crucial point is the dural opening, both for preservation of STA and MMA and to avoid damage to existing dural-pial collaterals. We would like to congratulate the authors for the comprehensive presentation and explanation of this interesting technique. It can be very useful, alone or combined with other procedures, especially when direct revascularization is not possible for technical reasons (e.g., when vessels are too small for bypass surgery) or when a previous revascularization treatment has failed.Even so, we would like to emphasize some limitations of this technique, suggested by literature and our experience. It is widely accepted in literature that burr hole surgery is effective only in selected adults and pediatric patients with MMD and accurate indication can make the difference in terms of outcome. Blauwblomme and colleagues [1] reported a series of sixty-four pediatric MMD patients treated with a large number of burr holes and the 89.1% of them had not suffered any recurrent stroke or TIA at long-term follow-up. Oliveira et al. [2] carried out similar results in a series of seven pediatric MMD patients treated with burr holes. They obtained an angiographic extensive collateralization by the external carotid artery in all the patients. Despite all these promising results, to the best of our knowledge, there is a lack of studies that suggest the superiority of burr hole surgery over other indirect revascularization techniques in MMD and MMS patients. Moreover, burr hole procedure carries the weakness that in case of failure, few rescue revascularization techniques are technically feasible.Pacetti et al. [4] reported a series of three pediatric This article is part of the Topical Collection on Vascular Neurosurgery Other