EXPLAINING CEREBRAL ANEURYSM

EXPLAINING CEREBRAL ANEURYSM

Definition

  An aneurysm is focal dilatation of the vessel wall

Types

,  Is most often a balloon-like outpouching, but may also be fusiform

Site

 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

 

 Risk of aneurysm

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

 

Symptoms and signs

 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

Investigations

Patients with symptoms suspicious for SAH should have a head

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

Treatment

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

SAH patients often require I to 3 weeks of lCU care after

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

Options for treating symptomatic vasospasm are intra-arterial papaverine and balloon angioplasty

, 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