Aneurysm, Intracranial

KEY FEATURES

Essentials of Diagnosis

• Subarachnoid hemorrhage or focal deficit

• Abnormal imaging studies

General Considerations

• Most aneurysms are located

  • On the anterior part of the circle of Willis, particularly the anterior or posterior communicating arteries

  • At the bifurcation of the middle cerebral artery

  • At the bifurcation of the internal carotid artery

• Saccular aneurysms ("berry" aneurysms)

  • Occur at arterial bifurcations

  • Are frequently multiple (20% of cases)

  • Are usually asymptomatic

  • Are associated with polycystic kidney disease, Moyamoya disease, familial aldosteronism type 1, and coarctation of the aorta

• Mycotic aneurysms resulting from septic embolism occur in more distal vessels and often at the cortical surface

Demographics

• Risk factors for aneurysm formation include cigarette smoking, hypertension, and female sex

CLINICAL FINDINGS

Symptoms and Signs

• Most are asymptomatic or produce only nonspecific symptoms until they rupture, causing a subarachnoid hemorrhage

• Subarachnoid hemorrhage onset is characterized by sudden, severe headache followed by nausea, vomiting and loss or impairment of consciousness that can be transient or progress to coma (see Subarachnoid Hemorrhage for manifestations, complications and management)

• "Warning leaks" of a small amount of blood from the aneurysm sometimes precede the major hemorrhage by a few hours or days, leading to headaches, nausea, and neck stiffness

• Aneurysms may cause focal neurological deficit

  • By compressing adjacent structures

  • Secondary to a focal hematoma or ischemia in the territory of the ruptured aneurysm vessel

• Vasospasm may lead to significant cerebral ischemia or infarction and increase in intracranial pressure

Differential Diagnosis

• Meningitis or meningoencephalitis

• Ischemic stroke

• Space-occupying lesion, eg, brain tumor

• Subdural hemorrhage

• Epidural hemorrhage

• Migraine

DIAGNOSIS

Imaging Studies

• Digital subtraction angiography (bilateral carotid and vertebral studies)

  • Definitive evaluation

  • Generally indicates the size and site of the lesion

  • Sometimes reveals multiple aneurysms

  • May show arterial spasm if rupture has occurred

• Visualization by CT or MR angiography

  • Not usually adequate if operative treatment is under consideration because lesions may be multiple and small lesions are sometimes missed

  • Can be used to screen patients who have two or more first-degree relatives with intracranial aneurysms

TREATMENT

Medications

• Medical management as outlined for subarachnoid hemorrhage is continued for about 6 weeks and followed by gradual mobilization

Surgery

• Definitive treatment requires either

  • Surgery and clipping of the aneurysm base, or

  • Endovascular treatment by interventional radiology

Therapeutic Procedures

• Major aim is to prevent further subarachnoid hemorrhages

• Symptomatic but unruptured aneurysms merit prompt treatment, either surgically or by endovascular techniques

• Decision to ...