What Is Brain Arteriovenous Malformation?

Cerebral arteriovenous malformation (AVM) is a congenital variation of local cerebral angiogenesis. The lack of capillaries between the cerebral arteries and cerebral veins at the diseased site causes the arteries and veins to communicate directly, forming a short circuit between arteries and veins, resulting in a series of cerebral hemodynamic disorders. Clinical manifestations often include repeated intracranial hemorrhage, partial or systemic seizures, transient ischemic attacks, and progressive neurological dysfunction, which is also the second cause of intracranial spontaneous subarachnoid hemorrhage.

Basic Information

nickname

Cerebral hemangioma

Visiting department

neurosurgery

Multiple groups

20 to 39 year old men

Common locations

Cerebrovascular

Common causes

Embryonic angiogenesis is caused by a disorder in the regulatory mechanism. Acquired pathological cerebral angiogenesis may also be one of the causes.

Common symptoms

Bleeding, epilepsy, headache, progressive neurological dysfunction, mental retardation, intracranial murmurs, eyeball protrusion

Causes of cerebral arteriovenous malformations

Cerebral arteriovenous malformations are generally believed to be caused by impediments in the regulation of embryonic angiogenesis. Arteriovenous malformations after streptococcal infection, new arteriovenous malformations after resection of arteriovenous malformations, arteriovenous malformations that occur simultaneously inside and outside the skull, and astrocytomas, oligodendrocytes, glioblastomas, blood supply Abundant reports of malignant meningiomas and metastatic cancer with arteriovenous malformations suggest that in addition to congenital factors, special circumstances such as those that can trigger pathological cerebral angiogenesis may also be the cause of cerebral arteriovenous malformations.

Arteriovenous malformations consist of a group of malformed blood vessels (vessel nests), which contain directly communicating arteries and veins, without capillaries; they are more common at the junction of the cortex and white matter, and are tapered, with the base facing the cerebral cortex and the tip Pointing deep into the white matter or directly to the lateral ventricle wall; there are one or more thickened blood supply arteries, and the drainage veins are dilated, distorted, and contain bright red arterial blood; deformed brain tissue (pathological features) is mixed between deformed blood vessel clusters, adjacent to the brain Parenchymal atrophy and even ischemic necrosis often occur in parenchyma.

Clinical classification of cerebral arteriovenous malformations

Spetzler & Martin (1986) classification is currently the most commonly used arteriovenous malformation grading method. The main indicators are whether there is obvious neurological function in the area where the arteriovenous malformation is located, the pattern of the drainage vein, and the maximum diameter of the arteriovenous malformation vascular group. Level plan:

1. Those who are located in the functional area (sensory, motor, language function, vision, thalamus and hypothalamus, inner capsule area, brain stem, cerebellar feet and deep cerebellum nucleus) score 1 point, otherwise listed as "quiet zone" 0 Minute;

2. If the drainage vein is partially or completely introduced into the deep vein, 1 point is scored, otherwise 0 is scored;

3. Small arteriovenous malformation (maximum diameter 6cm) is worth 3 points;

Add the above three scores, the lowest score is 1 point, the highest score is 5 points; those who are located in the brainstem and hypothalamus cannot be surgically resected are grade 6.

Clinical manifestations of cerebral arteriovenous malformations

Bleeding

It usually occurs in younger people and can be manifested as subarachnoid hemorrhage, intracerebral hemorrhage or subdural hemorrhage, often after sudden physical activity or mood swings, sudden severe headache, vomiting, loss of consciousness, neck stiffness, and Kernig sign are positive.

Epilepsy

Can be seen in 40% to 50% of patients, about half of the first symptoms, more common in larger arteriovenous malformations with a large number of "brain stealing blood", mainly partial seizures, can be secondary to systemic spread , With the typical characteristics of Jackson epilepsy.

3. headache

60% of patients have a long history of headache, mostly confined to one side, and the nature of the headache changes during bleeding.

4. Progressive neurological dysfunction

Mainly manifested as motor or sensory paralysis (see 40% of patients, 10% are the first symptoms), mainly due to transient ischemic attack caused by "brain stealing blood", cerebral edema caused by large arteriovenous malformations Brain atrophy and brain damage or compression caused by bleeding.

5. Intellectual decline

Most of the large arteriovenous malformations are diffuse ischemia and brain development disorders caused by severe "brain stealing blood", and can also be caused by repeated seizures and long-term use of antiepileptic drugs.

6. Intracranial murmur

Found in larger, superficial arteriovenous malformations.

7. Eye prominent

It is found on some diseased sides, especially when there is a large drainage vein leading to the cavernous sinus in the anterior arteriovenous malformation of the temporal lobe.

The clinical manifestations of subventricular arteriovenous malformations are more insidious than those above the scene, with fewer symptoms other than spontaneous subarachnoid hemorrhage.

Cerebral arteriovenous malformation

CT scan of the head

See local irregular low-density areas, calcification in the lesion, fresh bleeding, hematoma, cavity left after hematoma absorption or cerebral infarction; irregular and high density (equivalent to arteriovenous malformation), blood supply artery and drainage after enhancement vein.

2. Digital Subtraction Angiography (DSA)

The most characteristic: an irregularly distorted blood vessel group can be seen in the arterial phase radiograph. There are one or more thick, deep-developed blood supply arteries. Draining veins appear early on the arterial phase radiograph, distorted and expanded, and are introduced into the sinus. The cerebral arteries on the distal side of the lesion are poorly filled or not filled.

3.MRI (magnetic resonance imaging)

Vascular masses, blood supply arteries, and draining veins are all shown black due to the "empty effect".

Diagnosis of cerebral arteriovenous malformations

Young patients with spontaneous subarachnoid hemorrhage or intracerebral hemorrhage, especially authors who have had localized or generalized epilepsy, should suspect this disease.

Differential diagnosis of cerebral arteriovenous malformations

Cavernous hemangioma

It is one of the common causes of recurrent subarachnoid hemorrhage in young people. DSA is often negative. CT shows honeycomb in different density areas with calcifications, which can be slightly enhanced. The surrounding brain tissue is slightly edema, and there is rarely a placeholder effect. No large blood supply arteries or dilated, premature drainage veins; identification of intraoperative and pathological and occult arteriovenous malformations is required.

Epilepsy

Embolized cerebral arteriovenous malformations often have refractory epilepsy, may have hemiplegia and cerebellar ataxia, and are often misdiagnosed as epilepsy due to negative DSA; however, they often occur after subarachnoid hemorrhage, and CT removes large areas formed by focal atrophy. Outside the low-density area, small pieces of calcified shadows can be seen around the low-density area.

3. Gliomas

Glioma with abundant blood supply can cause subarachnoid hemorrhage. Arteriovenous communication and early veins can also be seen in DSA. However, there are still obvious space-occupying effects. There is no thickening and enlarged supply arteries. Draining veins do not dilate. Tortuous; and rapid development, short duration, often with symptoms of cranial hypertension and neurological deficits, CT and MRI can be clear.

4. Metastases

Patients with brain metastases such as chorionic epithelial cancer and melanoma may have subarachnoid hemorrhage, and DSA can show abundant vascular clusters and early veins; but they are older, have a shorter course, progress rapidly, and often have irregular blood vessels. Sinus-like, edema around the lesion is obviously accompanied by vascular displacement, and the primary lesion can be found.

5. Meningiomas

Angioblastic meningiomas may have similar clinical and DSA manifestations, but there are obvious signs of occupancy. There are no thickened blood supply arteries and dilated drainage veins. The blood supply blood vessels are "ball-shaped" and surround the tumor. CT is obvious. The enhanced tumor has clear boundaries, is close to the inner surface of the skull, adheres to the dura, and may have skull invasion.

6. Angio reticuloma (hematoblastoma)

Mostly cystic, small tumor nodules are located on the cyst wall; blood supply is mostly around the tumor; CT shows low-density cystic lesions, and enhanced tumor nodules are located on the side of the cyst wall; can be associated with erythrocytosis and Hemoglobin is abnormally elevated.

7. Intracranial aneurysm

The first cause of subarachnoid hemorrhage can be identified based on typical clinical manifestations and DSA.

8. Venous cerebrovascular malformations

Rarely, those located in the quadrilateral or near the fourth ventricle can block the aqueduct or the fourth ventricle and cause obstructive hydrocephalus. Cerebral angiography shows a thick vein with several collaterals. CT is a low density that can be enhanced. Lesions.

9.Moyamoya disease (moyamoya disease)

DSA showed that the internal carotid artery and middle cerebral artery were occluded, the anterior and posterior cerebral arteries had a countercurrent phenomenon, and there was an abnormal vascular network at the bottom of the brain. No reflux vein was seen.

Cerebral arteriovenous malformation

Principle

The main harms of cerebral arteriovenous malformations are bleeding and "steal blood", which can cause serious consequences. The most reasonable treatment is total resection. For low-level arteriovenous malformations, total resection can be considered as long as the patient is determined; The higher one has to weigh the pros and cons of surgery and treat it carefully because the scope of the lesion is too extensive or the site is critical. Neither convulsions or mild focal neurological dysfunction is an indication of surgery. Repeated bleeding of the lesion is an indication of surgery.

2. Non-surgical treatment

Applicable to other cases of arteriovenous malformations of grade 3 or higher, other cases without bleeding, and cases that are temporarily unsuitable for surgery; Contents include regulating daily life (avoid emotional excitement, smoking ban, dredge stools, improve sleep, lower blood pressure, 4 to 6 weeks in bed), control epilepsy, symptomatic treatment and prevent bleeding.

3. Surgical treatment

(1) Total resection of arteriovenous malformations is the most reasonable treatment option. The number, location, source, size, and involvement of the main blood supply arteries and drainage veins in the opposite side should be identified before surgery. Control intracranial pressure during operation; surgical incision large enough to expose the main blood supply artery; temporarily block the blood supply artery during operation and stop the brain protective agent if necessary; make full use of cerebral softening lesions and glial hyperplasia around arteriovenous malformations; Follow the procedure of cutting off the arteries, then the small veins, and finally the large main drainage vein; after each blood vessel is cut off, it must be firmly welded with bipolar coagulation, step by step.

(2) Blood-supplying arterial ligation is suitable for palliative surgery of arteriovenous malformations of grades 3 to 4 and above, which cannot be surgically removed and often has bleeding, or as a precursor operation in giant arteriovenous malformation; Can be significantly reduced, but there are still other cerebral arteries resupplying blood and causing bleeding.

4. Interventional Therapy

Artificial embolization and endovascular surgery (disconnecting from balloon catheters, electrolytic releasable coils) are suitable for those who cannot be surgically removed, and preparations before removal of huge arteriovenous malformations.

5. Radiology and Radiosurgery

(1) Indications: those who have difficulty or high risk of surgical resection, patients who are older or have other systemic diseases and are unable to tolerate surgery, those who have failed surgery or have large residuals after surgery, and those who refuse to undergo surgery

(2) Radiotherapy methods Stereotactic cyclotron helium ion surgery, Stereo cyclotron Bragg peak proton beam (photon) radiosurgery, Stereo cyclotron neutron beam surgery and Stereotactic focused gamma ray radiosurgery (Gamma knife treatment)

(3) Therapeutic effect It can reduce the risk of bleeding and maintain a normal life. It can be used as a choice for the deep brain and those who cannot be operated.

(4) Complications Bleeding, transient brain radiation reactions (cerebral edema, radiation brain, brain dysfunction), permanent brain dysfunction, and radiation brain necrosis.

Prognosis of cerebral arteriovenous malformations

Bleeding rate

Arteriovenous malformations tend to increase in children, and the bleeding rate also increases; arteriovenous malformations have a rebleeding rate of 6% in the first year after the first bleeding, and a rebleeding rate of 2% each year thereafter.

2. Epilepsy rate

Epilepsy is the first symptom, accounting for 17% to 40%; the seizures are mostly localized, and are generally closely related to the location and type of arteriovenous malformations. The incidence of epilepsy in the temporal and frontal lobe is higher than other parts The frontal lobe is more systemic and the parietal lobe is more limited. Surgery is the most important risk factor for epilepsy in patients.

3. Spontaneous thrombosis

Very rare, single reflux vein occlusion is the main cause of arteriovenous malformation and occlusion; it should be noted that although arteriovenous malformation has been occluded, bleeding may still occur, so surgery is still necessary.

4. Neuropsychiatric disorders

Most patients with arteriovenous malformations develop symptoms before the age of 40, with bleeding and epilepsy being the most common, showing transient progressive or permanent neurological dysfunction, heart failure, hydrocephalus and mental retardation, and even dementia.

5. Prognosis of surgery

Mortality is below 2% and disability rate is below 10%.