Moyamoya disease

Introduction to moyamoya disease Moyamoya disease, also known as moyamoya disease, is also called abnormal vascular network in the brain. It is a group of cerebrovascular diseases characterized by the narrowing or occlusion of the internal carotid artery siphon and the anterior and middle cerebral arteries, and the abnormal small blood vessels in the brain. . Because of the small vascular formation of many densely packed piles in cerebral angiography, it is named after the smoke spit out. basic knowledge The proportion of illness: 0.0001%-0.0003% Susceptible people: no special people Mode of infection: non-infectious Complications: renal artery stenosis hypertension intracranial aneurysm cerebral vascular malformation cerebral infarction epilepsy

Cause of moyamoya disease

Cerebrovascular malformation (55%):

The vascular group of the brain is not seen in the normal angiogram and belongs to the abnormal blood vessel. The disease is more common in children and there is no clear cause. Some cases incorporate other congenital cerebrovascular diseases such as cerebral aneurysms or cerebrovascular malformations.

Disease factors (45%):

The dynamic changes of cerebral angiography, clinical symptoms, and the course of disease progress progressively within a certain period of time, especially in children, and the progression of the disease course tends to be greater. There are many diseases that can cause this disease, such as meningitis, non-specific arteritis, multiple neurofibromatosis, radiation, trauma, syphilis, spirochete, tuberculous meningitis, brain tumor, intracranial infection, optic glioma, Senile atherosclerosis and chiasm tumors can cause similar pathological changes.

Pathogenesis

1. Pathological anatomy: There are three main changes in the pathological anatomical changes of moyamoya disease.

(1) Large vessel occlusion or extreme stenosis at the base of the brain: the internal carotid artery bifurcation, the anterior cerebral artery and the middle cerebral artery, the cerebral artery stenosis, occlusion, and the damaged artery appear small. Endothelial cell hyperplasia, thickening of the intima, thickening of the inner elastic layer, resulting in stenosis or occlusion of the arterial lumen, atrophy of the medial membrane, weak and partial disappearance, lymphocytic infiltration, occlusion of the internal carotid artery pathological changes The inner elastic layer is highly buckled, partially thinned, partially broken, partially stratified, partially thickened; the inner membrane is locally eccentrically thickened, there are smooth muscle cells, collagen fibers and elastic fibers in the inner membrane; the middle layer is obviously thinner. Most smooth muscle cells are necrotic and disappear, and the pathological properties of occlusive blood vessels are consistent with congenital arterial dysplasia, some are inflammatory or arteriosclerotic changes, and some are thrombosis. For example, leptospirosis is caused by arteritis. .

(2) abnormal vascular network: mainly located in the bottom of the brain and basal ganglia, which is characterized by thinning of the wall, expansion, increased number, easy to rupture and hemorrhage, etc. The abnormal vascular network is from the front of the Willis ring, the posterior choroidal artery, and the anterior cerebral artery. Middle or small musculoskeletal vessels of the middle cerebral artery and posterior cerebral artery. These vessels are usually difficult to distinguish between arteries and veins. The lining of the abnormal vascular network of small arteries can be seen with edema, thickening, middle-elastic fibrosis, and elastic layer. Thickening, rupture, so that the blood stasis, thrombosis occlusion, dilated small arteries can be characterized by middle fibrosis, thinning of the lumen, elastic fiber hyperplasia, thickening of the intima, etc., sometimes the inner elastic layer is broken, the middle layer is thin, forming Microaneurysm ruptures and hemorrhage, with the increase of age, the dilated blood vessels can be progressively thinned, the number is reduced, and the stenotic artery is increased.

(3) Changes in secondary blood circulation disorder in the brain parenchyma: manifested as pathological changes such as hemorrhagic or ischemic and brain atrophy.

Observation under electron microscopy showed that moyamoya disease is a wide-ranging disease affecting cerebral blood vessels. The most obvious change is the degeneration, necrosis, disappearance and destruction of the inner elastic layer of smooth muscle cells.

2. Pathophysiology: When the blood vessels are narrow and occlusion occurs, the collateral circulation is gradually formed, the collateral circulation increases and becomes mesh-like, and the lumen expands significantly to form an abnormal vascular network. The abnormal vascular network serves as a means of compensating blood supply. When the cerebral artery ring is occluded, the cerebral artery ring has lost its function as a powerful compensatory pathway. Therefore, only the blood vessels that originate from the proximal part of the occlusion site are compensated for blood supply through expansion and hyperplasia. The abnormal vascular network can continue the shape and the normal anterior and middle cerebral arteries. If the vascular occlusion site continues to develop to the proximal end, the origin of the abnormal vascular network may be occluded, resulting in the disappearance of the abnormal vascular network. The formation of an abnormal vascular network is a form of special compensatory blood supply for occlusion of a specific site, rather than an essential thing. It can be seen in the anterior part of the Willis ring and also in the posterior part. If the occlusion continues to develop, the abnormal vascular network is occluded. The starting point, or the occlusion site is at the proximal end of the starting point, then there is no abnormal blood vessel.

3. Pathogenesis: destruction of smooth muscle cells in the middle layer of blood vessels, hyperplasia and re-destruction, re-proliferation, and repeated morphological basis may be the pathogenesis of moyamoya disease.

When the blood vessels are narrowed or occluded, the collateral circulation is gradually established, forming an abnormal vascular network. Most abnormal vascular networks are formed by the increase and expansion of some primitive blood vessels. When the blood vessels are occluded so fast that sufficient collateral circulation is not formed. When repaying blood supply, then, clinically, it is a symptom of cerebral ischemia. If the vascular occlusion is formed, the proximal pressure increases, causing abnormally fragile, vascular network or other abnormal blood vessel rupture, and clinical intracranial hemorrhage occurs. Symptoms, when the intracranial aorta is completely occluded, the collateral circulation has been established, and the lesions stop developing. Due to the different vascular properties of the lesions, the degree of the lesions is different. After the formation of the collateral circulation, under the action of long-term blood flow disorders, new The formed blood vessels can develop lesions, so the clinical symptoms can be manifested as recurrent or alternating.

Moyamoya disease prevention

Early detection of moyamoya disease, early diagnosis and early treatment are the key. Through early surgical treatment, more than 80% of patients can return to normal life.

1. Pay attention to the functional exercise of rest and limbs.

2, strengthen nutrition, give high protein and high vitamin diet.

3, the occurrence of subarachnoid hemorrhage, can not move the patient, to avoid coughing, sneezing and breath holding defecation, etc. to increase the thoracic cavity, abdominal pressure action.

4, should prevent flooding, rodent control, poultry should be kept in captivity, prevent pollution of water sources, do a good job of drinking water disinfection.

5, educate children not to drink raw water, do not play water, bathing, etc. in the epidemic water, to avoid suffering from leptospirosis.

Moyamoya disease complications Complications renal artery stenosis hypertension intracranial aneurysm cerebral vascular malformation cerebral infarction epilepsy

1. The diseases that may be associated with moyamoya disease include renal artery stenosis hypertension, intracranial aneurysm, cerebrovascular malformation, primary pulmonary hypertension, periodic torticollis and developmental disorders.

There are two types of cerebral aneurysms associated with moyamoya disease:

(1) Ordinary intracranial aneurysms: aneurysms on the Willis ring are more common, but the distribution is different, mainly at the top of the basilar artery, which is related to the increased hemodynamic load of the vertebral basilar artery of this disease, followed by The internal carotid artery, middle cerebral artery and anterior communicating aneurysm are rare.

(2) smog or collateral aneurysms: These aneurysms can disappear by themselves if there is enough blood for compensation or revascularization.

In adults, these aneurysms are one of the causes of intracerebral hemorrhage, intraventricular hemorrhage and subarachnoid hemorrhage.

2. Postoperative complications

(1) Chronic subdural hematoma: may be related to high brain atrophy in cerebral infarction and antiplatelet agents such as aspirin.

(2) Hematoma in the anastomosis of the anastomosis: may be related to the rupture of the blood vessel wall and the postoperative hypertension.

(3) Ischemic symptoms: may be too thin with the recipient arteries, difficult to fit, the diaphragm of the diaphragm is compressed, the blood flow is temporarily blocked during anastomosis, the original collateral circulation is destroyed, and intraoperative hypocapnia is related.

(4) Other adverse reactions: postoperative headache, epilepsy, etc.

Symptoms of moyamoya disease Common symptoms Nausea intracranial hemorrhage Atrophy Pseudobulbar paralysis dementia

The reported age of onset was 2 years old, the largest was 65 years old, and the average was 29.25 years old. Most of the literature reported that the disease was more common in children and adolescents, and 30% to 45% under 15 years old.

Patients with this disease have rare blood pressure, generally no fever, often onset in the form of stroke, there may be two groups of symptoms of cerebral ischemia or cerebral hemorrhage, as follows:

Ischemic group

(1) The age of onset is relatively light, with an average age of 18.4 years. It is more common in children and adolescents. It is mostly acute and has subacute disease.

(2) Clinically, it can be expressed as cerebral thrombosis, and TIA can also occur. Patients often have multiple episodes of stroke. The literature reports that 13.3% of the authors, 60% of the two authors, and 26.7% of the three authors. .

(3) Frequent symptoms such as dizziness, headache, numbness, paralysis, lack of energy, and unclear speech on the onset of the disease often occur after the limbs of one side are improved and the limbs of the other side are paralyzed. In the case of all-in-one, hemispherical lesions may have aphasia, and those with multiple lesions may have pseudobulbar paralysis, mental disorders, mental retardation or dementia, and about 40% of patients have seizures.

(4) At the time of CT or MRI examination, 80% of the brain showed multiple infarcts.

2. Bleeding group

(1) The age of onset was much later than that of the ischemic group, with an average age of onset of 33.1 years, mostly young and middle-aged.

(2) normal blood pressure, sudden onset, common bleeding site for subarachnoid hemorrhage, primary ventricular hemorrhage and cerebral hemorrhage, the above three kinds of bleeding accounted for 78% to 90% of the intracranial hemorrhage of the disease, rare for the shell Nuclear hemorrhage, thalamic hemorrhage and tail nucleus hemorrhage, so the intracranial hemorrhage caused by moyamoya disease is mostly bleeding with obvious signs.

(3) often with headache, nausea and vomiting, some patients may have different degrees of disturbance of consciousness, the clinical symptoms and signs are the same as other causes of intracranial hemorrhage, the prognosis seems to be better, it has been reported that 18 cases of moyamoya disease caused by intracranial hemorrhage Patients, followed up for 5.4 years, 13 patients (72.2%) had a good prognosis, and 5 patients (27.8%) had one or more recurrences.

It is worth mentioning that moyamoya disease causes more primary ventricular hemorrhage, which is the main cause of primary ventricular hemorrhage. It is easy to hemorrhage except for the ventricular wall and the miliary aneurysm rupture. The important reason is Infarctual hemorrhage, because the blood around the ventricle is a group of blood vessels extending from the ventricle surface to the parenchyma, consisting of the anterior and posterior cholangio-macular branches, the blood vessels distributed from the ventricles, and the other group passing through the brain parenchyma. The peripheral arteries distributed around the ventricles are supplied. The blood vessels in both groups are terminal branches, and basically no anastomosis occurs, which constitutes the marginal zone. At the same time, these distal branches are farthest from the heart, and are hyperplasia after the lesions of the main blood vessels of the Willis arterial ring. , compensated for small arteries, it is easy to cause ischemic softening of the ventricular wall, infarct bleeding.

Moyamoya disease check

Medical examination

There are no fundus edema, limb paralysis, aphasia and meningeal irritation.

Laboratory inspection

1. General laboratory tests: many no specific changes, general laboratory tests including blood routine, erythrocyte sedimentation rate, anti-"O", C-reactive protein, mucin determination, tuberculin test and serum leptospirosis test, blood routine Most patients have a white blood cell count below 10×109/L; the erythrocyte sedimentation rate can be slightly higher, most of them are normal; the anti-0 can be slightly higher and normal; if the patient is caused by tuberculous meningitis, the tuberculin skin test can be strong. Positive; if it is caused by leptospirosis, the serum leptospirosis test can be positive.

2. Cerebrospinal fluid examination: The examination of cerebrospinal fluid is similar to other cerebrovascular diseases. Children are mostly ischemic, cerebrospinal fluid examination is normal, and lumbar puncture pressure can be normal. If tuberculous meningitis is present, the patient's cerebrospinal fluid is tuberculous. Meningitis reaction, that is, the number of cerebrospinal fluid cells increased, sugar and chloride decreased, protein increased, such as leptospirosis, the patient's cerebrospinal fluid Leptospira immune response can be positive, if there is rupture bleeding, lumbar puncture cerebrospinal fluid examination can appear There is blood clot in blood cerebrospinal fluid or cerebrospinal fluid. If the cerebrospinal fluid is red at 24 hours after hemorrhage, uniform red blood cells can be seen in the cerebrospinal fluid. After 24 hours, the cerebrospinal fluid is brownish yellow or yellow. After 1 to 3 weeks, the yellow color disappears, and the white blood cells in the cerebrospinal fluid rise. High, early neutrophils, lymphocytosis in the late stage, this is the blood inflammatory response caused by meningeal stimulation, protein content can also be increased, usually around 1g / L, cerebrospinal fluid pressure is more than 1.57 ~ 2.35 kPa.

Film degree exam

1. EEG: generally no specific changes, whether it is bleeding patients or infarction patients, their EEG performance is about the same, both showed side or side slow wave increase, and there are a wide range of moderate to severe rhythm disorders According to the different waveforms generated by the abnormal computer map, different parts can be divided into three types:

(1) The posterior hemisphere of the brain: a high-order one-way paroxysmal or non-paroxysmal delta wave, limited to the posterior hemisphere of the brain, with an obvious side of ischemia.

(2) : The medium-high, continuous wave and wave are mainly limited to the middle part of the temporal lobe, and it is also dominant on the obvious side of ischemia.

(3) Scattered hair: a diffuse low-middle amplitude wave, excessive ventilation can induce slow waves, improve the positive rate of EEG diagnosis, excessive ventilation induced slow wave mechanism, and may be related to brain tissue blood supply dynamics Changes and changes in the pH of the arterial blood in the brain.

2. Cerebral angiography: cerebral angiography is the main means of diagnosis of this disease, and its cerebral angiography is characterized by:

(1) There is severe stenosis or occlusion in the upper part of the bilateral internal carotid artery bed and the anterior and middle cerebral arteries: the narrowing or occlusion of the first segment of the neck of the internal carotid artery is almost 100%, extending to the neck. 2 patients accounted for 50%, a small number of patients can extend to the neck 3, neck 4, while the distal vascular morphology of the occlusion segment is normal, bilateral cerebral angiography is basically the same, but the two sides are not completely symmetrical, a few cases only one side The abnormal manifestations of the above-mentioned blood vessels generally begin on one side and then develop into bilateral sides, first involving the first half of the Willis ring, and then developing to the second half until the entire arterial ring is occluded, resulting in basal ganglia, thalamus, hypothalamus. The cerebral occlusion of the brain-stem through the brain, such as the brain stem, forms an abnormal vascular compensatory collateral circulation at the base of the brain.

(2) There is a significant telangiectasia network at the basal ganglia: a collateral circulation centered on the internal and external striatum and thalamic arteries, the thalamic geniculate arteries, and the anterior and posterior choroidal arteries.

(3) There are extensive and abundant collateral circulation formation, including the establishment of intracranial and external anastomotic vessels: the collateral circulation pathway has the following three categories:

1 When the end of the internal carotid siphon is occluded, a collateral circulation is formed through an anastomosis between the posterior cerebral artery and the anterior and middle cerebral arteries.

2 The undamaged arterial ring and all the arterial branches of the siphon are involved in the blood supply of the basal ganglia, forming a collateral circulation to supply the branches of the anterior and middle cerebral arteries. Therefore, the basal ganglia forms a very rich abnormal vascular network. The most important collateral circulation pathway of the disease.

3 The branch of the external carotid artery is anastomosed to the pial vessels on the surface of the brain.

3. CT scan: Moyamoya disease can be performed separately or in combination in the CT scan.

(1) Multiple cerebral infarction: This is due to repeated occlusion of blood vessels in different parts. Multiple cerebral infarction may be old, or may be neoplastic, and there may be brain softening lesions of different sizes.

(2) secondary brain atrophy: mostly localized brain atrophy, this brain atrophy is directly related to the extent of internal carotid artery occlusion, and the more severe the internal carotid artery stenosis, the worse the blood supply, the brain atrophy The more obvious, and the collateral circulation is good, there is no brain atrophy on CT, brain atrophy occurs in the temporal lobe, frontal lobe, occipital lobe, peaks in 2 to 4 weeks, and then gradually improve, the reason for its improvement may be related to the lateral branch There is a certain relationship between loop creation.

(3) ventricular enlargement: about half of the patients have enlarged ventricles, enlarged ventricles and ipsilateral lesions, can also be bilateral, ventricular enlargement often coincides with brain atrophy, ventricular enlargement and intracranial hemorrhage have a certain relationship, severe brain atrophy With ventricle enlargement, there is no history of intracranial hemorrhage in the past, and mild brain atrophy with obvious ventricular enlargement, in the past there is a history of intracranial hemorrhage, which may be adhesion after subarachnoid hemorrhage, affecting the circulation of cerebrospinal fluid.

(4) intracranial hemorrhage: 61.6% to 77.3% of patients with moyamoya disease can occur intracranial hemorrhage, the most common subarachnoid hemorrhage, accounting for about 60%, intraventricular hemorrhage is also more common, accounting for 28.6% to 60%, more cobwebs Intramembranous hemorrhage, 30% of intraventricular hemorrhage is primary intraventricular hemorrhage, which is caused by rupture of abnormal vascular network. Intracerebral hematoma is more common in frontal lobe, irregular in shape, inconsistent in size, adjacent to the ventricle, It can rupture and hemorrhage, the hematoma enters the ventricle, and the adjacent brain pool can rupture and form subarachnoid hemorrhage.

(5) Enhanced CT scan: It can be seen that the blood vessels near the basilar artery ring become thinner, poorly developed or not developed, and abnormal vascular clusters with point-like or arc-like enhancement can be seen around the basal ganglia and the ventricles, and the distribution is irregular.

4. MRI: Magnetic resonance can show pathological changes in the following moyamoya disease:

(1) Both the old and the recent cerebral infarction showed long T1 and long T2, and the brain softening was also long T1 and long T2, showing a low-density signal on the T1-weighted image and a high signal on the T2-weighted image.

(2) Intracranial hemorrhage showed high signal in all imaging sequences.

(3) Localized brain atrophy is most prominent in the frontal lobe and temporal lobe.

(4) The abnormal vascular network at the base of the skull is a honeycomb or reticular low-signal vascular image due to the airflow effect.

Diagnosis and identification of moyamoya disease

diagnosis

At present, the internationally accepted diagnostic criteria for moyamoya disease is adopted. The standard established by the Japanese Society of Moyamoya Disease in 1997 is that the cause is unknown and the DSA or MRA is consistent with the end of the internal carotid artery and the anterior and middle cerebral artery. Or) occlusion; arterial phase showing abnormal smog-like vascular network; lesions are bilateral; at the same time exclude the following diseases: atherosclerosis, autoimmune diseases, meningitis, brain tumors, Down's syndrome, brain trauma, Radiation head irradiation and hyperthyroidism; possible moyamoya disease, ie unilateral lesions in children or adults, should also be excluded.

Imaging examination is currently the main means of diagnosing moyamoya disease. Domestic Peking Union Medical College Hospital uses transcranial Doppler ultrasonography (TCD) to screen out many patients with clinically suspicious or unexplained moyamoya disease, TCD can find more ischemic and In the case of adult moyamoya patients with clinical symptoms of atypical vascular disease, digital subtraction angiography (DSA) is still the most accurate and reliable diagnostic method. Magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) can be Most smoke sick patients make a definitive diagnosis.

Differential diagnosis

The disease needs to be differentiated from cerebral atherosclerosis, cerebral aneurysm or cerebral arteriovenous malformation, and it is generally difficult to identify according to clinical manifestations and changes in cerebral angiography.

1. Cerebral arteriosclerosis: Most patients with internal carotid artery occlusion caused by cerebral arteriosclerosis are elderly, often have many years of hypertension, high blood lipid history, cerebral angiography showed sudden interruption of arteries or irregular stenosis, generally no abnormal blood vessels The web appears.

2. Cerebral aneurysm or cerebral arteriovenous malformation: For subarachnoid hemorrhage caused by moyamoya hemorrhage, it should be differentiated from aneurysm or cerebral arteriovenous malformation. Cerebral angiography can show aneurysm or thickening blood supply. Arteries, agglomerated malformed blood vessels and abnormally large drainage veins, without internal carotid artery stenosis, occlusion and collateral circulation, can be identified.

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