A limited cystic dilatation of the cerebral artery wall. The etiology is mostly congenital malformations, followed by infections and atherosclerosis. The peak age of onset is between 50 and 54 years, with a slightly higher incidence in women than in men. The location of the aneurysm is mostly in the intracranial segment of the internal carotid artery, followed by the anterior and middle cerebral arteries, and less frequently in the posterior cerebral artery. Introduction Brain Aneurysm; Cerebral Aneurysm Symptom Stage Spontaneous subarachnoid hemorrhage is the first symptom, accounting for about 80% to 90%. Sudden headache, nausea, vomiting, cervical tonicity or partial impairment of consciousness are often seen during exertion or agitation, and cerebrospinal fluid is seen to be bloody by lumbar puncture. Depending on the amount of bleeding and the location of the aneurysm, there may be specific neurological signs, such as internal carotid artery-posterior communicating artery aneurysm bleeding, there may be ipsilateral arteriovenous nerve palsy (eyelid ptosis, limited eye movement, dilated pupil); if the bleeding is large enough to form a huge hematoma, the patient may die within a short time. Typical attacks The clinical diagnosis is not difficult for those with typical attacks, and the diagnosis can be confirmed by CT scan to determine the side and angiography. In the examination, it should be active and steady, and early angiography should be performed in milder cases. Treatment time Most of the time, aneurysm neck clamping surgery is performed before the second hemangioma rupture. The operative mortality rate has decreased to 5% or 0. In critically ill patients, conservative treatment is often performed, and the prognosis is poor. The congenital defect of the arterial wall is believed to be a congenital lack of smooth muscle layer in the arterial bifurcation of the intracranial ring of Willis. The theory of acquired degeneration of the arterial wall suggests that intracranial atherosclerosis and hypertension. The arterial elastomeric plates are destroyed and gradually bulge to form a cystic aneurysm. In addition, infectious lesions in the body such as bacterial endocarditis and pulmonary infections can lead to infected aneurysms by shedding infectious emboli and eroding the wall of cerebral arteries; head trauma can also lead to aneurysm formation. However, they are rare in clinical practice. Cerebral aneurysms are localized areas of particular weakness in the blood vessel wall of the intracerebral arteries, which gradually expand outward under the impact of long-term blood flow, forming small balloon-like hemangiomas. The higher the local blood flow pressure, the higher the risk of aneurysm rupture. When rupture occurs, blood enters the surrounding tissue. Sometimes, the aneurysm does not rupture, but because of its increased size, it can compress nearby nerves, causing the corresponding symptoms. The image on the right is an image of an aneurysm in an angiogram. Causes 1. The following causes may lead to aneurysms: 2. hypertension or arteriosclerosis in the brain 3. cerebral thrombosis 4. certain types of infections (also called bacterial aneurysms) 5. head trauma 6. heredity 7. drug use such as cocaine Cerebral aneurysm pathophysiology Histological examination reveals that only a layer of intima exists in the aneurysm wall, lacking middle smooth muscle tissue, and the elastic fibers are broken or missing. The aneurysm wall was infiltrated by inflammatory cells. Electron microscopy reveals the loss of elastic plates in the aneurysm wall. Giant aneurysms often have thrombosis or even calcification, and the straight emboli are layered in an “onion” shape. Aneurysms are cystic, spherical or berry-shaped. The aneurysm has a purplish-red appearance, and the wall is extremely thin, with intraoperative vortexes of blood flow visible. The apex of the aneurysm is much weaker, and 98% of aneurysm bleeds are located at the apex of the aneurysm. The ruptured aneurysm is surrounded by a hematoma, and the ruptured apex is adherent to the surrounding tissue. Aneurysms of the internal carotid artery system account for approximately 90% of intracranial aneurysms, including internal carotid artery-posterior communicating aneurysms, anterior artery-anterior communicating aneurysms, and middle artery aneurysms; ② aneurysms of the vertebrobasilar system account for approximately 10% of intracranial aneurysms, including vertebral aneurysms, basilar aneurysms, and posterior cerebral aneurysms. Aneurysms less than 0.5 cm in diameter are small, 0.6-1,5 cm in diameter are general, 1.6-2.5 cm in diameter are large, and those larger than 2.5 cm in diameter are giant. Aneurysms with small diameters have more chances of bleeding. Intracranial multiple aneurysms account for about 20% of all aneurysms, with two being the most common and three or more. Signs and symptoms Cerebral aneurysms may not cause any symptoms until they rupture, but about half of the patients have warning symptoms before the aneurysm bleeds heavily. Secondly, the aneurysm may compress the adjacent nerve tissues and cause symptoms such as ptosis, inability to open one eye, diplopia, hemianopia, loss of vision and facial pain. In addition, ischemic symptoms such as dizziness may also occur due to vasospasm. The best way to reduce mortality and disability is to treat cerebral aneurysms before they bleed. Once the cerebral aneurysm ruptures, there is usually a sudden and severe headache, which is an instant and unexperienced severe head pain like splitting on a clear sky, instead of a slow headache little by little; this headache can extend to the neck, shoulder, waist and back and lower limbs, accompanied by nausea, vomiting, pale face, cold sweat, and more than half of them have different degrees of consciousness impairment, with the lighter ones being briefly confused, and the heavier ones In severe cases, the patient may die due to brain herniation. It is important to note that some patients may have sudden onset of severe headache as the only symptom, so further examination is necessary to exclude cerebral aneurysm rupture and bleeding.