The management of MMD includes medical treatment and surgical treatment. Platelet aggregation inhibitorsor calcium channel blockers[22,23] may generate excellent but transient effects could be only applied to mild casesor acute phase of stroke .Surgical treatment is considered to be the most effective method to treat MMD, especially for MMD, manifesting as a cerebral ischemic symptom.However, few studies focus on the surgical treatment of epileptic type MMD, and there is a lack of randomized controlled studies and meta-analysis. Thus, we reviewed the current literature and summarized the efficacy of surgical treatment for epileptic type MMD.
We calculated an overall pooled postoperative incidence of seizure in patients with epileptic type MMD, which was 21.52%. That means the rate of seizure freedom after surgery in this population is about 78%. As we know, surgery in children with refractory epilepsy resulted in higher rates of seizure freedom and better outcome than medical therapy alone . The most effective surgery is for temporal lobe epilepsy. The seizure-free rate ten years after surgery for temporal lobe epilepsy is about 50% , which is still lower than the rate for epileptic type MMD. Furthermore, most of the patients with epileptic type MMD suffered seizures after surgery could be controlled by anti-epileptic drugs[15,17,18], but only very few patients deteriorated or without improvement after surgery[2,19].
Surgical complications of MMD include hyperperfusion syndrome, intracranial hemorrhage, infarction, local hypoperfusion, poor scalp healing and infection, and epilepsy . The incidence of seizures after revascularization in MMD patients was 10.9–18.9% [6,8]. Thus, the seizure recurrence in some of the patients with epileptic type MMD is not because of epilepsy itself, but because of the surgery. Some of the postoperative seizure is associated with increased cerebral cortex excitability caused by increased blood flow . Since the improvement of cerebral hemodynamics, MMD patients with this type of postoperative seizures have been confirmed to have a good prognosis following synangiosis .
The pathogenesis of MMD presented with epilepsy is not very clear. Most scholars believed that it could be associated with ischemia . The epileptic type of MMD has an analogical progression as the ischemic stroke type of MMD .In a cohort study, 4 out of 7 patients with epileptic type MMD showed decreased cerebral perfusion. Since decreased cerebral perfusion could give rise to disturbance of cerebrovascular reactivity and could result in regional cerebral hypoxia, seizure recurrence should be prevented by the cerebral perfusion improvement via revascularization surgery .
We also calculated the overall pooled postoperative incidence of ischemic events in patients with epileptic type MMD, which was 7.42%.A review from 1,448 pediatric MMD patients showed that the rate of perioperative ischemic events was4.4-6.1%, which was lower than the rate in epileptic type MMD from our calculation. However, that may be because of the limitation of the number of studies included in our study. Choi et al.  reported that surgery could prevent epileptic seizures and obtained more approving clinical outcomes when applied to patients with epileptic type MMD compared to ischemic type MMD, but there were no differences in postoperative neuroimaging and hemodynamic changes between the two groups.
Since the postoperative incidence of seizure and the ischemic event showed low heterogeneity and publication bias in our study, we did not analyze the risk factors for epilepsy and ischemic event after cerebral revascularization in patients with epileptic type MMD. Different operation methods (indirect, direct, or combined), age of patients, course of epilepsy, and severity of clinical presentations may affect the prognosis of operation. Only one study  explored the risk factor of seizure recurrence in epileptic type MMD. They identified the duration of epilepsy as an independent risk factor for recurrent seizure after surgery in pediatric patients with epileptic type MMD, but the surgical modalities would not affect the outcome of the surgery. Nevertheless, no other studies discussed the correlation between the course of epilepsy and seizure recurrence. These suggest us to do more studies, including more patients with epileptic type MMD under different conditions.
Evidence from this study suggests that the postoperative incidence of seizure and ischemic events is relatively low. Surgery is an effective and secure therapy for patients with epileptic type MMD.
There were several limitations in our study: the numbers of patients and studies were all tiny, and all of these studies were retrospective and nonrandomized. That may because the incidence of epileptic type MMD is relatively low, and few scholars focus on this type of MMD. Follow-up periods were not consistent among individuals, ranging from 0.2 to 25 years, which implies that the observational time of some patients may not be sufficient. In a word, future studies should focus on the epileptic type MMD in large-scale randomized controlled clinical studies.