Intracranial aneurysm is a cerebrovascular disease with subarachnoid hemorrhage as the main manifestation. Its incidence is much higher than people think. Among the cerebrovascular diseases, intracranial aneurysm ranks third after cerebral thrombosis and hypertensive cerebral hemorrhage. The Department of Neurosurgery of Nanjing Brain Hospital once made a statistic and found an interesting phenomenon that intracranial aneurysms are more likely to occur in middle-aged and elderly women and are prone to rupture and bleeding in winter. Intracranial aneurysm is equivalent to a “time bomb” in the skull, once ruptured, the death or disability rate is extremely high. Nearly half of all patients die upon first rupture. Even if they survive, the risk of re-rupture is extremely high. If the aneurysm is not treated promptly, most patients will die within a few years, making it a veritable “cold-blooded killer. However, it is a curable disease, and with advances in science and technology, most patients can recover after treatment. What is an intracranial aneurysm? An intracranial aneurysm is not a tumor, but a localized bulge in the wall of an intracranial blood vessel, like an inflated rubber water pipe, which once ruptured, the water inside the pipe will gush out. Clinically, a ruptured aneurysm is often highlighted by a severe headache, with the patient describing the pain as cracking or exploding. What are the symptoms of an aneurysm? Intracranial aneurysms that have not ruptured do not usually cause any clinical symptoms. This results in many patients presenting to the hospital only after the aneurysm has ruptured and bled. A small number of large or massive aneurysms (20 mm or greater than 25 mm in diameter) may cause neurological deficits before they rupture, such as actinic nerve palsy, ptosis, visual impairment, hypopituitarism, or limb immobility. Once an aneurysm ruptures and bleeds, severe headaches often occur, along with frequent vomiting, profuse sweating, body temperature may rise, and neck tonicity. Impaired consciousness and even coma may also occur. In nearly half of the patients, aneurysm rupture is followed by death due to untimely diagnosis and treatment. In addition to bleeding, ruptured aneurysms can also trigger cerebral vasospasm, which mostly occurs 3-14 days after subarachnoid hemorrhage. The clot stimulates the vessel wall and causes strong vasoconstriction through various mechanisms, which in severe cases can lead to ischemic necrosis of brain tissue, coma and hemiplegia of the patient. If early surgery is performed, in addition to clamping the aneurysm to further eliminate the risk of rebleeding, the clot can be removed during surgery, and various measures and drugs can be used to prevent cerebral vasospasm and promote patient recovery. How can intracranial aneurysms be diagnosed? Many patients, and even some physicians, only administer medications for subarachnoid hemorrhage after it occurs, without further examination of the cause of the hemorrhage, thus losing the opportunity for timely treatment of the aneurysm. All patients with subarachnoid hemorrhage should be routinely examined with neuroimaging techniques, such as CTA, MRA, and DSA, to make a definitive diagnosis of the aneurysm. DSA (digital subtraction cerebral angiography): generally considered the “gold standard” for the diagnosis of intracranial aneurysms, this test has a higher sensitivity and CTA and MRA are basically non-invasive examination methods, painless to patients and inexpensive, and can be used as screening methods for intracranial aneurysms. How should patients with intracranial aneurysms be treated? After a patient is diagnosed with an intracranial aneurysm and treated conservatively, about 70% of patients will die from rebleeding of the aneurysm. It is estimated that after the first rupture of an aneurysm, the mortality rate is as high as 30-40%, half of which die within 48 hours after the onset of the disease. In surviving cases, 1/3 of them may have rebleeding, and the mortality rate of those with rebleeding is as high as 70-80%. Patients with milder conditions should be examined as early as possible for early surgery. If the patient is in a coma, which indicates severe bleeding or cerebrovascular spasm, surgery is more dangerous. Some patients need to wait for two weeks after their condition has improved before considering surgery. There are two main treatment methods for intracranial aneurysm: one is open aneurysm clamping and the other is aneurysm lumen embolization (interventional treatment) via femoral artery cannulation. Closure treatment: Intracranial aneurysm clamping is the most commonly used treatment method and has a long history and is effective in treating most aneurysms. The material used to make the aneurysm clips is titanium alloy, which is not affected by MRI, airport security equipment, or metal detectors. The neurosurgeon makes an incision at the site of the aneurysm, removes the bone flap, exposes the intracerebral structures, and reaches the aneurysm through the gap between the brain and skull base without damaging brain tissue. Under a surgical microscope, the aneurysm is carefully separated along the normal cerebral artery, and then the neck of the aneurysm (the area where the aneurysm connects to the cerebral vessels) is clamped with an aneurysm clip so that blood flow from the cerebral vessels does not enter the aneurysm and the aneurysm does not rupture. The advantage is that if the aneurysm is completely clamped, there is no residue and the recurrence rate is very low. It is also suitable for patients who have a large intracranial hematoma in combination, and the hematoma can be removed at the same time during the surgery. Many people mistakenly believe that opening the cranial cavity is dangerous, but in fact, due to the minimally invasive technique especially for unruptured aneurysms, the operation can be completed with a bone window of only 3 cm in diameter, and there is basically no damage to the brain tissue.