1.Definition of intracranial aneurysm
Intracranial aneurysms are caused by local congenital defects in the wall of cerebral arteries and increased intracranial pressure, and are abnormal protrusions on the wall of intracranial arteries, usually on the large arteries at the base of the brain, often accompanied by weaknesses and defects in the wall structure. The aneurysms are congenital (developmental) aneurysms, infected aneurysms, traumatic aneurysms, atherosclerotic aneurysms, and dissecting aneurysms. The age of prevalence is 40-60 years old, and it is more common in women.
2. Prevalent sites of intracranial aneurysm
Anterior circulation: 85%, anterior cerebral artery: 30%, internal carotid artery: 30%, middle cerebral artery: 25%, posterior circulation: 15%, posterior cerebral artery: 2%, basilar artery: 10%, vertebral artery: 3%.
Saccular aneurysms are more common and vary in shape and size, with those less than 14mm in diameter being small, those 15-24mm being large, and those over 25mm being giant. Trauma can also cause aneurysm, but it is less common.
3.Ruptured intracranial aneurysm causes
About 1/3 of the subarachnoid hemorrhage caused by aneurysm rupture occurs during strenuous exercise, emotional excitement, coughing, holding stool, weight bearing, trauma and surgery are also the main causes of aneurysm rupture.
4.Symptoms of intracranial aneurysm
1.Compression symptoms
Brain fatty aneurysms produce corresponding compression symptoms depending on their different locations. When the aneurysm enlarges, headache may appear, which is located in the orbit on the side of the disease and is pulsating; protrusion of the eye on the side of the disease, ptosis of the eyelid, limited abduction of the eye, mild hemiparesis, motor aphasia, mental disorder, uveitis, seizure and rhinorrhea may also appear.
2.Rupture precursor
Aneurysm expansion often causes limited headache, eye pain, vision loss, nausea, neck stiffness, vertigo and movement or sensory disturbance, which may be the aura of cerebral aneurysm rupture. When the diameter of aneurysm exceeds 2.5 cm, it may cause symptoms of increased intracranial pressure.
3.Hemorrhage symptoms
After rupture of cerebral aneurysm, symptoms of subarachnoid hemorrhage will appear, such as severe headache, nausea and vomiting, meningeal irritation, fever, and may be accompanied by convulsions, impaired consciousness and arteriovenous nerve palsy. After the rupture of cerebral aneurysm, the patient’s symptoms are often repeatedly aggravated after re-bleeding, and the consciousness impairment is deepened or new symptoms and signs appear again.
5.Auxiliary examination
1.CT: The diagnostic positivity rate of SHA within 24 hours is 92%. It should be noted that sometimes only intracerebral hematoma, intraventricular hemorrhage, ventricular enlargement (lateral ventricular inferior pedicle), etc. are shown.
2, lumbar puncture: when CT does not support SHA, it can be diagnosed by lumbar puncture. The detection rate of hemorrhagic cerebrospinal fluid is 3%. (Puncture is prohibited when intracranial pressure is hyperactive)
3.Cerebral arteriogram: It is the “gold standard” for diagnosing the source of hemorrhage, with a positive rate of 80-85%. Advantages: high sensitivity and specificity, dynamic observation of collateral circulation, etc. Disadvantages: invasive, the rate of rebleeding in DSA is 1-2% on average and 4.8% within 6 hours. Therefore, it is recommended to perform after 6 hours of onset.
4, CTA: The sensitivity is equivalent to DSA, advantages: high sensitivity and specificity, can grasp the peri-tumor vessels, bone three-dimensional structure, the first choice of examination during craniotomy. Non-invasive. Short examination time. Disadvantages: dynamic observation of the collateral circulation is not possible.2 Aneurysms less than 5 mm have a high negative rate.
5, RA: Sensitivity is lower than DSA, not preferred in the acute phase. Advantages: non-invasive. It is possible to grasp the three-dimensional structure of the peri-aneurysmal vessels and bone. Disadvantages: dynamic observation of collateral circulation is not possible. The negative rate is high for aneurysms smaller than 5 mm. Long examination time.
6.Aneurysm grading ( Hunt-Hess)
Grade 0 No rupture
Grade I consciousness, no neurological deficit, mild headache and neck straightness.
Grade Ia clear consciousness, more fixed neurological symptoms (chronic phase)
Grade II clear consciousness, moderate or more headache, cervical tonicity, may have neurological deficits.
Grade III drowsiness, confusion, mild focal neurological deficits.
Grade IV coma, moderate or greater hemiparesis, and denervation.
Grade V deep coma, deactivation of the brain.
7.Differential diagnosis
1.In the presence of intracerebral hematoma, it should be differentiated from hypertensive cerebral hemorrhage.
2.It should be differentiated from vascular malformation and venous embolism (by CTA,DSA angiography ).
8.Comorbidities
1.Rehemorrhage: the risk factor of rehemorrhage is 4.1% within 24 hours, 19% within two weeks and 50% within six months.
2. Acute hydrocephalus: 15-20% incidence, mostly in posterior circulation aneurysms. The mortality rate of aneurysm rupture combined with hydrocephalus is higher, and the frequency of cerebral infarction is also higher.
3.Pulmonary edema: neurogenic pulmonary edema.
4.Electrocardiographic abnormalities: The main cause of occurrence is hypothalamic ischemia, with an incidence of 50%. It manifests as heart rate arrhythmia, T-wave inversion, QT segment prolongation, ST segment elevation or decrease, and the appearance of U wave. It usually improves within 5 days after the onset, and 10% of patients induce myocardial infarction.
5.Electrolyte disorders: disorders of antidiuretic secretion or salt depletion syndrome lead to hyponatremia and hypovolemia, which can cause delayed cerebral infarction in severe cases.
9.Treatment of cerebral aneurysm
Once a patient is diagnosed with “intracranial aneurysm”, about 70% of patients will die from aneurysm rebleeding if they are treated conservatively. According to statistics, after the first rupture of aneurysm, the mortality rate is as high as 30-40%, half of them die within 48 hours after the onset of the disease, and among the surviving cases, 1/3 of them may suffer from rebleeding, and the mortality rate of those who suffer from rebleeding is as high as 70-80%. At present, there are two methods of treating intracranial aneurysms, namely, direct microscopic surgery (aneurysm clamping) and neurointerventional surgery (aneurysm embolization). Both methods can achieve the purpose of curing aneurysm, preventing rebleeding, and reducing the disability and mortality rate.
1.Aneurysm Closure
It is a surgical method to treat aneurysm directly under the microscope, i.e. craniotomy. A special aneurysm clip is used to clip the neck of the aneurysm and protect the patency of the aneurysm-carrying artery.
2.Aneurysm embolization
Since the neurointerventional treatment of cerebral aneurysm has entered a revolutionary stage of rapid, minimally invasive, safe and effective treatment, the death and disability rate of the disease has been greatly reduced.
Indications for the procedure
① Patients of advanced age and poor general condition.
② Patients who have improved symptoms after external drainage of cerebrospinal fluid in severe SHA (Grade IV-V)
③ Posterior circulation aneurysm, periocular artery, saccular aneurysm with direct surgical access difficulties (internal carotid artery sea surface sinus segment, etc.)
④ Patients in the cerebral vasospasm phase who can undergo interventional vasospasm treatment at the same time
⑤ Patients whose condition improves after stage I embolization treatment in the acute stage, stage II embolization radical surgery is feasible.
⑥ No severe arteriosclerosis, vascular torsion, or rupture and bleeding after vasospasm is not severe.
【Surgical method】.
Through cerebral angiography, the site and type of aneurysm are clarified, embolization material is delivered into the aneurysm cavity using microcatheter technology, and embolic substances such as balloon or spring ring are used to occlude the aneurysm so that the aneurysm thromboses by itself to achieve the treatment purpose.
Advantages of aneurysm embolization]
①Low erosivity to the whole body. Puncture is performed in the femoral artery at the root of the thigh, and the incision is about 2 mm.
②Low trauma to brain tissue. No craniotomy.
③Short operation time.
④No damage to the normal perivascular penetrating vessels, which can reduce surgical complications.
⑤Aneurysm rupture can be stopped by first-stage embolization, and then radical surgery can be performed after the dangerous period.