Intracranial aneurysms are mostly abnormal bulges in the walls of intracranial arteries and are the first cause of subarachnoid hemorrhage, ranking third after cerebral thrombosis and hypertensive cerebral hemorrhage among cerebrovascular accidents. It can develop at any age, mostly in middle-aged and elderly women between 40 and 60 years old. Most scholars believe that intracranial aneurysms are caused by local congenital defects in the walls of intracranial arteries and increased intraluminal pressure, and that hypertension, cerebral atherosclerosis, and vasculitis are related to the occurrence and development of aneurysms. Intracranial aneurysms are usually found in the arterial ring at the base of the brain (Willis ring), of which 80% occur in the anterior half of the arterial ring at the base of the brain.
Clinical presentation
Prior to rupture and bleeding, 90% of patients with intracranial aneurysms have no obvious symptoms or signs, and only a very small number of patients have specific manifestations due to the aneurysm affecting adjacent nerves or brain structures. Symptoms and signs of aneurysm can be broadly classified into pre-rupture aura symptoms, rupture bleeding symptoms, localized signs and symptoms of increased intracranial pressure.
Aura symptoms
Forty to 60 percent of aneurysms have some aura symptoms before rupture because there is often a sudden expansion or a small amount of localized blood leakage before rupture. Among them, arteriovenous nerve palsy is the most lateralized and localized aneurysm augmentation symptom of posterior communicating artery.
Bleeding symptoms
In 80% to 90% of patients with aneurysms, subarachnoid hemorrhage due to rupture is the most common symptom of hemorrhage.
(1) Causes and onset: Some patients often have obvious causes before aneurysm rupture, such as heavy physical labor, coughing, straining to defecate, running, after drinking, emotional excitement, anxiety, and sexual life. Some patients may have no obvious trigger, or even occur during sleep. Most patients have sudden onset, usually with headache and impaired consciousness as the most common and prominent manifestations.
(2) Focal neurological symptoms caused by hemorrhage: The neurological symptoms caused by subarachnoid hemorrhage are meningeal irritation, manifested by a stiff neck and a positive Creutzfeldt-Jakob sign. Hemorrhage of the anterior cerebral artery aneurysm often invades the frontal lobe of the cerebral hemisphere, causing dementia, memory loss, urinary and fecal incontinence, hemiparesis, and aphasia. Hemorrhage of middle cerebral artery aneurysm often causes temporal lobe hematoma, which manifests as hemiplegia, hemianopia, aphasia and temporal lobe herniation. The ruptured posterior communicating artery aneurysm may cause ipsilateral arteriovenous nerve palsy and other symptoms.
(3) Systemic symptoms: After rupture and bleeding, a series of systemic symptoms may appear.
A. Elevated blood pressure: after the onset of the disease, the patient’s blood pressure increases suddenly, often temporarily, and usually returns to normal after a few days to 3 weeks.
B. Elevated body temperature: Most patients do not exceed 39℃, mostly around 38℃, and the elevated body temperature often occurs 24-96h after the onset of the disease, and usually returns to normal within 5 days to 2 weeks.
C. Cerebrocardiac syndrome: Clinical manifestations include transient hypertension, impaired consciousness, respiratory distress, acute pulmonary edema, epilepsy, and in severe cases, acute myocardial infarction (mostly occurring within the first week after onset) within 1 to 2 days after the onset of the disease. The more severe the impairment of consciousness, the higher the chance of ECG abnormalities.
D. Gastrointestinal bleeding: A few patients may show signs of upper gastrointestinal bleeding, manifested as vomiting coffee-like material or tarry stools.
(4) Re-bleeding: Once the aneurysm ruptures, it will bleed repeatedly, and the re-bleeding rate is 9.8%-30%. According to statistics, the time of rebleeding is often 7-14 days after the last bleeding, 10% in the first week, 11% in one year, and 3% in longer time.
(5) Local localization symptoms: Aneurysm rupture may be preceded by direct compression of adjacent structures and symptoms, which have localization significance in diagnosis. Common localization symptoms include
(1) Cranial nerve symptoms: This is one of the most common local localization symptoms caused by aneurysm, with the most common involvement of the articulatory nerve, trigeminal nerve, talocrural nerve and spinal nerve.
Aneurysms in the anterior half of the ring of Willis, such as anterior cerebral artery aneurysms and anterior communicating artery aneurysms, can compress the visual crossings and cause bilateral temporal hemianopia or compression of the visual tracts and cause isotropic hemianopia.
③Migraine: Typical migraine caused by aneurysm is not common, and its incidence is 1% to 4%. Most of the headaches are sudden, often around one orbit, and most of them are pulsating pain. Compression of the ipsilateral common carotid artery can temporarily relieve the pain.
(6) Symptoms of increased intracranial pressure: It is generally believed that unruptured giant aneurysms with a diameter of more than 2.5 cm or ruptured aneurysms with intracranial hematoma can cause increased intracranial pressure. The change of fundus edema caused by giant type aneurysm is different from the change of fundus edema and hemorrhage caused by ruptured hemorrhage. The former is optic disc edema caused by increased intracranial pressure, while the latter is mostly optic disc edema and retinal hemorrhage caused by subarachnoid hemorrhage.
(7) Special manifestations: Aneurysms may sometimes present with some special manifestations. For example, internal carotid artery aneurysm or anterior communicating artery aneurysm may present with headache, bilateral temporal hemianopia, limb hypertrophy, pituitary hypoplasia and other manifestations of saddle area tumor. Transient cerebral ischemia may also be the main manifestation in individual cases; a few patients may develop acute mental disorder after aneurysm rupture and bleeding, which may manifest as acute confusion, disorientation, excitement, hallucination, incoherent speech and irritable behavior.
(8) Clinical grading: Hunt and Hess classified patients with intracranial aneurysm into five grades according to their clinical manifestations, which are used to assess the risk of surgery.
Grade I: asymptomatic, or mild headache and mild neck stiffness.
Grade II: moderate to severe headache, neck tonicity, and no neurological deficits other than cerebral nerve palsy.
Grade III: drowsiness, confusion, or mild focal neurological deficits.
Grade IV: lignation, moderate to severe lateral incomplete paralysis, possible early decortical tonicity and autonomic nervous system dysfunction.
Grade V: deep coma, decortical tonicity, near-death state.