Smoldering disease (moyamoyadisease), also known as skull base anomalous vascular network disease, is a chronic occlusive cerebrovascular disease characterized by progressive stenosis or occlusion of the ends of the internal carotid arteries bilaterally and the formation of an anomalous vascular network at the skull base. Its clinical manifestations are mainly cerebral ischemic symptoms in children and cerebral hemorrhage symptoms in adult patients. At present, the clinical treatment of smog is divided into pharmacological treatment and surgical treatment, the latter being the main one.
I. Drug treatment
When the cerebral perfusion reserve is still in the normal range, it is only appropriate to carry out conservative medical treatment for the time being, otherwise overly aggressive revascularization surgery may cause the brain tissue to be overperfused, resulting in the rise of intracranial pressure, and even the normal perfusion pressure breakthrough syndrome; while when the cerebral perfusion reserve has decreased, surgery should be carried out as soon as possible. The main drugs currently applied are antiplatelet agents, vasodilators, antifibrinolytics and fibrinolytics, and other drugs including anticonvulsants and steroids, which are used in patients with epileptic type and with increased intracranial pressure, respectively. Antiplatelet agents mainly prevent cerebral embolism by preventing the formation of microthrombi at arterial stenoses; calcium antagonists reduce the frequency and severity of recurrent TIAs and are effective in refractory headaches or migraines in patients with smog, but need to be used with caution because they can cause a drop in blood pressure. The effect of all the above drugs is inexact, and hemodynamic reconstruction with surgical intervention is the most effective means of improving hemodynamics and reducing secondary stroke.
II. Surgical treatment
1. Basis of surgical treatment
O-gawa’s study on cerebral blood flow (CBF) by 133Xe intravenous injection showed that CBF in the cerebral hemispheres of both Moyamoya disease and normal subjects declined with age, and the decline was more pronounced in the Moyamoya disease group; local cerebral blood flow (rCBF) was predominant in the frontal lobe of normal subjects, whereas in Moyamoya disease it was significantly predominant in the occipital lobe, suggesting that ischemia in the ICA system was more pronounced. The predominance of local cerebral blood flow (rCBF) in the frontal lobe in normal subjects and in the occipital lobe in Moyamoya disease suggests more pronounced ischemia in the ICA system. The hemispheric CBF in adolescent patients correlates with the degree of angiographic occlusion, with CBF decreasing with increasing occlusion and rCBF showing a significant occipital lobe increase with increasing occlusion. Thus, in theory, any surgical approach that directly increases cortical CBF (especially anterior CBF) is an option, and direct anastomotic bypass surgery is based on this.
In the natural situation, the formation of collateral circulation between extracranial and cortical vessels is restricted, creating conditions for such collateral anastomoses, and indirect bypass surgery has long been used to treat Moyamoya disease and has made substantial progress in recent years. In addition, the formation of collateral vessels after indirect bypass surgery can also reduce intracranial hemorrhage caused by microaneurysm formation and rupture due to spontaneous collateral vessel overdilation.
2. Timing and indications for surgery
Kim et al. followed up 204 children who underwent indirect revascularization. They divided these children into three groups according to their age, with the boundary of 3 and 6 years old. They found that children under 3 years old had the most frequent complaints of cerebral infarction (87%), the highest incidence of preoperative cerebral infarction (39%), and the lowest probability of a better prognosis (58%), and the poor clinical prognosis was mainly related to the occurrence of preoperative infarction. Therefore, early diagnosis and treatment are important for the development of intelligence. The indications for simultaneous treatment are: (i) significant cerebral ischemia and recurrent clinical symptoms. ②Reduced regional cerebral blood flow, vascular response and cerebral perfusion reserve, etc.
3.Postoperative complications
Complications after Moyamoya disease bypass surgery include: new symptoms of cerebral ischemia or aggravation of existing symptoms, intracranial hemorrhage, seizure-like epilepsy, wound and/or intracranial infection. Among them, the frequency of TIA or RIND seizures increased after surgery, and most of them gradually decreased in a short period of time. Matsushima et al. found one case of cerebral infarction and one case with seizure after 22 EDAS. Matsushima found 6 cases of cerebral infarction after EDAS on 161 sides, and suggested that this was related to postoperative crying of the child, which led to hyperventilation and further decrease in cerebral blood supply due to cerebral vasoconstriction, which was already in a critical state. Prevention should avoid stimulation of the child, and sedation should be given if necessary.
Three surgical methods
1.Direct vascular anastomosis
It is also called direct bypass surgery, mainly refers to superficial temporal artery-middle cerebral artery anastomosis (Superficialtemporalarterytomiddlecerebralarteryanastomosis, STA-MCA).
2.Encephalo-duro-arterio-synangiosis (EDAS) EDAS is performed by freeing the main trunk of the superficial temporal artery with fascias on both sides, without severing the distal end, then cutting the temporal muscle along the superficial temporal artery and lifting it into two flaps, drilling cranial holes along the two ends of the free superficial temporal artery trunk, making free bone flaps, then cutting the dura In 1979, Matsushima et al. first treated a 9-year-old child with Moyamoya disease with paroxysmal limb weakness and seizures using right-sided EDAS surgery, with no postoperative complications. Follow-up confirmed improvement in cognition and a decrease in the number of seizures with limb weakness. 6 months later cerebral angiography showed significant revascularization in the ischemic area. adelson and Scott [11], on the other hand, modified the EDAS procedure by widely opening the arachnoid and applying the artery to the surface of the brain, creating an apposition of the brain, artery and soft meninges. They treated 143 patients with lateral Moyamoya disease with this procedure, and most of them had no cerebral infarction and no reoccurrence of TIA, with a good prognosis at long-term follow-up.
Matsushima et al. analyzed the cognitive status of the two groups of patients about 10 years after the EDAS procedure to determine the difference between surgical treatment and non-surgical natural course. The difference between the natural course of the disease and the non-surgical course was determined. The total intelligence quotient (FIQ), vocabulary intelligence quotient (VIQ) and behavioral intelligence quotient (PIQ) were measured. Starke et al. performed the procedure on 43 North American patients with smog and followed them up (4-126 months, mean 41 months), showing that the neurological status of most patients was protected or improved after the procedure and that cerebral ischemic events in the hemisphere on the operated side decreased by 89 percent.
3. Encephalo-duro-arterio-myo-synangiosis (EDAMS)
4.Encephalo-myo-synangio-sis (EMS)
5.Multipleburr-operation of the skull
6.Large omental graft
7, direct and indirect vascular anastomosis surgery combined
Hint: Smog is still a difficult clinical treatment problem, and further research on genetic genetics is needed. In treatment, symptomatic treatment and individualized design of surgical plan can be adopted to stop the progression of the disease to the maximum extent and improve the prognosis. A randomized prospective clinical trial comparing different surgical procedures will help clinicians to determine the indications for surgery and the best surgical approach.