Dural arteriovenous malformation
Introduction
Introduction to dural arteriovenous malformation Dural arteriovenous malformation (DAVM) is an arteriovenous communication or arteriovenous fistula in the dura mater. The dura mater of the dura mater or intracranial arteries supplies blood and returns to the sinus or arterial meningeal vein, essentially DAVM is one or more arteriovenous fistulas based on the dura mater, so it was also called dural arteriovenous fistula in the past. However, most of the arteriovenous fistulas are acquired lesions. The name "dural arteriovenous malformation" can better reflect the innate source characteristics of some lesions. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: spinal cord ischemia
Cause
The cause of dural arteriovenous malformation
Congenital factors (30%):
Some people think that the dural arteriovenous malformation is related to the congenital small arteriovenous circuit expansion. Robinson believes that the nourishing blood vessels of the intracranial sinus are derived from the external carotid artery system. If there is dysplasia, it is easy to form the external carotid artery - cavernous fistula. In the early stage of the embryo, the transverse sinus is closely related to the external carotid artery, so the dural arteriovenous malformation often occurs in the transverse sinus area. In addition, some people think that the dural arteriovenous malformation is related to sinusitis.
External factors such as trauma, surgery, etc. (30%):
Trauma, surgery and other external factors can cause the reticulum between the arteriovenous and venous sinus to open, forming arteriovenous fistula, most scholars emphasize that dural arteriovenous malformation and sinusitis are closely related, due to venous sinus embolism After the formation of new blood vessels.
Pathology (30%):
The natural course of the disease varies greatly and is difficult to predict. Some lesions are accidentally discovered and can remain unchanged for many years; some patients have clear symptoms (such as tinnitus or intracranial murmur), but the lesions do not develop progressively, and even the formed thrombus can Natural remission, especially in the cavernous sinus DAVM, often occurs spontaneous occlusion, but some of the lesions progressively expand, rupture, causing intracranial fatal bleeding or neurological damage.
Various factors cause the formation of DAVM, which causes a series of intracranial hemodynamics and pathophysiological changes.
Prevention
Dural arteriovenous malformation prevention
Early detection and early treatment are the key to prevention. Have a full physical examination every year on a regular basis. If the presence of dural arteriovenous malformations has been found, it should be treated aggressively and surgically removed if necessary. Maintaining a good mentality after surgery, active physical exercise, good working hours and eating habits can increase resistance and avoid recurrence of the disease.
Complication
Complications of dural arteriovenous malformation Complications spinal cord ischemia
Some patients with mixed dural arteriovenous malformations may have scalp vascular engorgement, distortion, and even formation of vascular mass. When the dural arteriovenous malformation of the posterior cranial fossa drains into the spinal cord vein, it may cause intraspinal venous hypertension, leading to spinal cord ischemia. Spinal cord damage appears, and high blood flow may be accompanied by heart enlargement and heart failure.
Symptom
Dural arteriovenous malformation symptoms Common symptoms Intracranial hemorrhage venous return disorder Tinnitus vascular murmur hydrocephalus increased intracranial pressure double vision
Because the dural arteriovenous malformation is located outside the brain, unless the dural arteriovenous malformation is returned to the sinus and is accompanied by sinus cortical vein reflux, the dural arteriovenous malformation is directly returned to the cortical vein or dural arteriovenous malformation with large venous pool. Very few manifestations of neurological symptoms and signs, common symptoms and signs of dural arteriovenous malformations are:
1. Intracranial vascular murmur This is the most common clinical manifestation of dural arteriovenous malformation. 67% to 79% of patients have subjective or objective vascular murmurs. The murmur is consistent with the pulse, showing a roaring sound, persistence, and becoming a patient. The most unbearable symptoms, the degree of intracranial vascular murmur is related to the blood flow and location of the dura mater. If the vertebral artery is not involved in blood supply, the compression of the carotid artery murmur may be weakened or disappeared.
2. Headaches Many patients with dural arteriovenous malformations have headaches. The possible causes are:
(1) Dural arteriovenous malformation "stolen blood" is severe, resulting in dural ischemia.
(2) Increased intracranial pressure.
(3) intracranial hemorrhage.
(4) Stimulation of the meninges by the deformed blood vessels.
(5) Persistent intracranial vascular murmur can cause mental stress and poor rest, and headaches can also occur.
3. The factors that increase intracranial pressure caused by increased intracranial pressure and dural arteriovenous malformation are:
(1) Increased cerebral blood flow and dura mater sinus pressure, accompanied by decreased cerebrospinal fluid absorption and increased cerebrospinal fluid pressure.
(2) The intracranial and extracranial arteries communicate directly with the sinus. A large amount of arterial blood directly enters the sinus, causing the venous sinus pressure to increase. As the venous sinus pressure increases, the cortical venous return disorder and cerebral congestion.
(3) Dural arteriovenous malformation directly into the cortical vein causes cerebral congestion.
(4) Secondary venous sinus thrombosis.
(5) The occupying effect caused by the huge subdural venous lake, or the occupying effect of the posterior cranial fossa arteriovenous malformation, causes cerebrospinal fluid circulation disorder and forms obstructive hydrocephalus.
4. Intracranial hemorrhage is another common clinical manifestation of dural arteriovenous malformation. A considerable number of patients have subarachnoid hemorrhage as the first symptom, mainly cortical drainage venous rupture, which is due to the lack of dural arteriovenous malformation. Capillaries, arterial pressure directly into the drainage vein of the dura mater, when the pressure exceeds the load on the vein wall, that is, rupture of bleeding, the literature reported that 85% of patients have enlarged venous tumors or varicose veins at the vein end of the deformed blood vessels, which It is the root cause of bleeding. The incidence of intracranial hemorrhage caused by dural arteriovenous malformation in different parts is also different. The subarachnoid hemorrhage or intracerebral hemorrhage often occurs in the anterior cranial fossa of the cranial anterior fossa. This is because the cranial anterior fossa dura mater Arteriovenous malformation has a unique venous return method, that is, the blood first flows back to the soft meningeal vein of the prefrontal lobe, and then these veins flow into the superior sagittal sinus or cavernous sinus, and the drainage vein is a dural arteriovenous malformation of the cortical vein. The chance of internal bleeding was 20% and 42%, respectively. The incidence of bleeding near the main sinus was 7.5%, located far away. The main venous sinus bleeding incidence of 51%.
5. Others may have epilepsy, tinnitus, hemiparesis, aphasia, transient darkness, etc., cavernous sinus dural arteriovenous malformation may occur after frontotemporal or post-ball pain, exophthalmos, vision loss, diplopia, eye movement nerve Obstacles and so on.
Examine
Examination of dural arteriovenous malformation
No special performance.
Cerebral angiography
It is the most important means of diagnosis and classification of DAVM. It can clearly show the performance of malformed vessels from arterial phase to venous phase, which is beneficial to the classification of lesions and understanding the relationship between angiographic changes and clinical manifestations and prognosis, especially observation. The involvement of the venous sinus with or without embolization and venous return has a decisive effect on the design of the treatment plan.
Note on angiography:
(1) Six angiograms should be performed, that is, bilateral internal carotid artery, external carotid artery and vertebral artery were separately imaged.
(2) The lesion in the large area of the occipital region should be added for aortic arch angiography.
(3) The film should be placed in the early stage of the artery and maintained to the venous phase.
(4) Digital subtraction techniques and superselective intubation techniques should be used to increase the diagnostic value of cerebral angiography.
2. Magnetic resonance angiography / venography (MRA / MRV)
It can non-invasively display the anatomical structure of the dural arteriovenous, but the resolution is poor, which can not meet the clinical diagnosis requirements. At present, it is only one of the means of screening and following up the DAVM.
3.CT scan
CT scans can help detect lesions and intracranial hemorrhage. CT findings of dural arteriovenous malformations can be as follows:
1 worm-like or patchy contrast enhancement;
2 local occupancy effect;
3 large sinus expansion;
4 ventricle enlargement, mainly caused by hydrocephalus caused by poor absorption of cerebrospinal fluid or dural omental arteriovenous malformation;
5 The white matter density was significantly reduced, mainly due to cerebral parenchymal venous infarction caused by venous return disorder, edema and other reasons;
6 vascular indentation enlargement in the inner plate of the skull;
7 Intracranial hemorrhage can be seen in the subarachnoid space or high density in the brain. Three-dimensional computed tomography revascularization (3D-CTA) uses spiral CT to obtain enhanced intracranial vascular information, reconstruct blood vessel type, and clearly show abnormal blood vessels. The three-dimensional structure has important reference value for the choice of treatment plan and surgical approach, and has received more and more attention.
4. Magnetic resonance imaging (MRI)
It can be used as a means of screening and differential diagnosis of DAVM. On MRI, most of them have no signal-induced vascular shadows, which are grape-like or honeycomb-like black shadows, and can clearly show their blood supply artery and drainage vein, showing lesions. The thickness of the dura mater and the thrombus in the sinus, but this type of examination can not show the dynamic changes of blood flow in DAVM, and it does not help the choice of treatment and prognosis.
Diagnosis
Diagnosis and diagnosis of dural arteriovenous malformation
diagnosis
Diagnosis can generally be made based on the patient's clinical presentation and imaging, especially the performance of cerebral angiography.
Differential diagnosis
Should pay attention to the differentiation of cerebral arteriovenous malformations, sudden subarachnoid hemorrhage under the age of 40, history of epilepsy or hemiparesis before hemorrhage, aphasia, headache history, and no obvious increase in intracranial pressure, should be highly suspected Arteriovenous malformations, but a clear differential diagnosis depends on cerebral angiography, CT and MRI.
