EXPLAINING CEREBRAL ANEURYSM
Definition
An aneurysm is focal dilatation of the vessel wall
, Is most often a balloon-like outpouching, but may also be fusiform
Aneurysms usually occur at branch points of major vessels e.g, internal carotid artery (lCA) bifurcation, or at the origin of smaller vessels e.g., posterior communicating artery or ophthalmic artery
Approximately 85% of aneurysms arise from the anterior circulation (carotid) and 15% from the posterior circulation
vertebrobasilar
Aneurysms are thin-walled and at risk for rupture. The major cerebral vessels, and therefore aneurysms, lie in the subarachnoid space. Rupture results in subarachnoid hemorrhage (SAH) . The aneurysmal tear may be small and seal quickly or not
SAH may consist of a thin layer of blood in the CSF spaces, or thick layers of blood around the brain and extending into brain parencbyma. resulting in a clot with mass effect. The meningeal linings of the brain are sensitive
SAH usually results in a sudden, severe thunderclap headache. A patient will classically describe the worst headache of my life. Presenting neurologic symptoms may range from mild headache to coma to sudden death. The Hunt-Hess grading system categorizes patients clinically
CT immediately. Acute SAH appears as a bright signal in the fissures and CSF cisterns around the base of the brain
CT is rapid, noninvasive, and approximately 95% sensitive. Patients with suspicious symptoms but negative head CT should undergo lumber puncture
Lumbar puncture (LP) with Xanthochromia and high red blood cells counts is consistent with SAH , negative CT and LP essentially rules out SAH
Patients diagnosed with SAH require four vessels cerebral angiography within 24 hours to assess for aneurysm or other vascular malformation
Catheter angiography remains the gold standard for assessing the patients cerebral vasculature SAH
Patients should be admitted to the neurologic ICU hunt Hess grade 4 to 5 patients require intubation and hemodynamic monitoring and stabilization
, The current standard of care for ruptured aneurysms requires early aneurysmal occlusion there are two options for occlusion
The patient may under go craniotomy with microsurgical dissection and placement of a titanium clip across the aneurysm neck to exclude the aneurysm from the circulation and reconstitute the lumen of the parent vessel
The second option is to take the patient to the interventional neuroradiology suite for endovascular placement of looped titanium coils inside the aneurysm dome. The coils support thrombosis and prevent blood flow into the aneurysm
Factors favoring craniotomy and clipping
Include young age, good medical condition, and broad aneurysm necks
Factors favoring coiling
Include old age or medically-frail patients and narrow aneurysm necks
Clipping results in a more definitive cure, because coils can move and compact over time, requiring repeat angiograms and placement of additional coils
The decision to clip or coil is complex and should be fully explored
Debate also continues regarding optimal care for unruptured intracranial aneurysms
aneurysm occlusion for medical complications that accompany neurologic injury. In addition to routine ICU concerns, SAH patients are also at risk for cerebral vasospasm
In vasospasm, cerebral arteries constrict pathologically and can cause ischemia or stroke from 4 to 21 days after SAH
Current vasospasm prophylaxis includes maintaining hypertension and mild hypervolemia to optimize perfusion, and administering nimodipine, a calcium channel blocker that may
decrease the incidence and degree of spasm
Neurointerventional
, Aneurysmal SAH has an approximate mortality rate of 50% in the first month. Approximately one-third of survivors returns to pre SAH function, and the remaining two-thirds have mild to severe disability. Most require rehabilitation after hospitalization
tags:cerebral,explaining,aneurysm
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