INTRACRANIAL ANEURYSMS

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Common cause of nontraumatic intracranial hemorrhage:
-saccular aneurysm
-ateriovenous malformation
-hypertensive hemorrhage
-spontaneous lobar hemorrhage

Surgical treatment of aneurysm or arteriovenous malformation includes:
-elective repair to prevent hemorrhage
-emergent repair to prevent further complications of a preexisting intracranial hemorrhage

Cerebral aneurysms
-commonly occurs at the bifurcation of large arteries within the base of the brain
-majority of aneurysms are located at the anterior circle of Willis
-most common cause of SAH is rupture of a saccular aneurysm
-incidence of saccular aneurysm is approximately 5%
-acute mortality following rupture of a saccular aneurysm is approximately 10%
-aneurysm size greater than 7 mm is generally considered for surgical correction

Unruptured aneurysms
-headache: most common presenting symptom of an unruptured aneurysm
-CNIII palsy: most common presenting sign of an unruptured aneurysm

Other possible manifestations associated with unruptured aneurysm:
-brainstem dysfunction
-visual field defects
-trigeminal neuralgia
-cavernous sinus syndrome
-seizures
-hypothalamic-pituitary dysfunction

Common diagnostic techniques for aneurysm include:
-angiography
-MRI angiography
-helical CT angiography

Therapeutic intervention includes:
-elective clipping of cerebral aneurysm
-obliteration of cerebral aneurysm

Ruptured aneurysms
-more often acute presentation occurs due to SAH
-less often occurs due to hemorrhage into the epidural space or within the brain
-common complaint of: severe headache
-headache often associated with nausea and vomiting
-sudden ↑ ICP and ↓ CePP may present as a transient loss of consciousness
-uncorrected ↑ ICP may lead to death eventually leading to herination of brain
delayed complications of ruptured cerebral aneurysm include:
-cerebral vasospasm
-re-rupture of pre-existing cerebral aneurysm
-hydrocephalus

Cerebral vasospasm
-major cause of morbidity and mortality of patients with a ruptured cerebral aneurysm
-occurs in approximately 30% of patients who experience ruptured cerebral aneurysm
-etiology not fully understood but may be associated with blood clot near the cerebral artery
-manifestation related to severity of and distribution of cerebral artery involved
-usually occurs within 4 –14 days
-vasospasm prevention attempted with CCB
-once vasospasm occurs CCB generally are ineffective

Prevention of cerebral vasospasm attempted with:
-prevention cerebral vasospasm attempted with nimodipine and nicardipine

Treatment of cerebral vasospasm with:
“triple H” therapy which includes:
-hypervolemia
-hypertension
-hemodilution

Mild hypertension is preferred to marked hypertension:
-due to increased risk of rebleeding from a previously ruptured cerebral aneurysm
-accomplished by dopamine infusion