BSN Notes: Neurology- Cerebral aneurysms

Cerebral aneurysms

Introduction

A brain aneurysm, also called a cerebral or intracranial aneurysm, is an abnormal bulging outward of one of the arteries in the brain.

Brain aneurysms are often discovered when they rupture, causing bleeding into the brain or the space closely surrounding the brain called the subarachnoid space, causing a subarachnoid hemorrhage.

INCIDENCE

•         75% of subarachnoid hemorrhages

•         12% die before receiving medical help.

•         40% of hospitalized patients die within I month.

•         More than 1/3 lives with major neurologic deficits.

RUPTURED

•         20% morbidity

•         20% mortality

UNRUPTURED

•         4% morbidity

•         0.2% mortality

Classification of aneurysm

·     According to size

·     Fusiform aneurysm

·     Saccular aneurysm

·     Dissecting aneurysm

·     According to cause

·     True aneurysm

·     False aneurysm

Fusiform aneurysm — it is a diffuse dilation that involves the entire circumference of the arterial segment that is whole artery.

Saccular aneurysm- it is a distension of a vessel projecting from one side. Saccular aneurysm is a distinct, localized out pouching of the arterial wall.

Dissecting aneurysm - Are the result of traumatic tear of an arterial Hemorrhage or intramural hematoma, separating the layers of an arterial wall. Commonly involves arch of aorta

According to cause

True aneurysm- results of the slow weakening of the arterial wall caused by long term disease such as hypertension, atherosclerosis etc.

False aneurysm- pseudo aneurysm caused by traumatic break in the arterial wall.

         OTHER CLASSIFICATION

•         Small- less then 12mm 78%

•         Large- 12-24mm. 2%

•         Giant- 24mm.      2%

RISK FACTORS

·         Genetic

·         Age over 50 years.

·         Female gender.

·         Cigarette smoking.

·         Cocaine use- drug abuse

·         Infection of vessel wall.

·         Head trauma.

·         Intracranial neoplasm/neoplastic emboli.

·         HTN.

     Alcohol.

·         Constant stress

·         Atherosclerosis and arteriosclerosis

PATHO PATHOLOGY

Due to etiological factors

·         Weakness of the vessel wall

·         Abnormal dilation of the wall of the artery

·         Rupture of an aneurysmal due to intra-aneurysmal pressure and thinning of vessel wall

·         Blood leaks into the subarachnoid space may cause increase ICP and ischemia  Subarachnoid hemorrhage

    Grading of cerebral aneurysm

Hunt- Hess scale

Grade 0  Unruptured asymptomatic discovery

Grade I         Asymptomatic or minimal headache with slight nuchal rigidity

Grade II   Moderate to severe headache , nuchal rigidity, no neurologic deficit other than cranial nerve palsy

Grade III    Drowsiness, confusion or mild focal deficit(hemiparesis) or combination

Grade IV      Stupor , moderate to severe deficit , decerebrate posturing

Grade V   Deep coma, decerebrate posturing, moribound.

CLINICAL PRESENTATION

Symptoms of unruptured aneurysm

I . Acute

 Severe headache

 Transient ischemia

o 2.Chronic	Seizures Oculomotor nerve palsy/vision loss
o	headache Chronic loss of vision Unilateral optic neuropathy
o	Motor weakness/cranial neuropathy Facial pain

ONLY 11%OF ANEURYSMS CAUSES SYMPTOMS

 

Diagnosis

·         History and physical examination

·         Cerebral angiography

·         CT angiography

·         EEG

·         CT

·         MRI

·         CSF analysis

Medical management

•          Administer nitroprusside / antihypertensive agents and close monitoring of blood pressure

•          Administer calcium channel blockers such as nimodepine to prevent vasospasm

•          Prophylactic antiepileptic drugs to prevent /control seizures such as phenytoin, phenobarbital.

Aneurysm precautions

       Complete bed rest with head elevated 30 degree

•          Intravenous fluids

•          Avoidance of valsalva maneuver and neck flexion

•           Decreasing environmental stimuli 

•          Limitations of visitors

•          Administration of analgesic and sedatives

Surgical management

       There are two common treatment options for rupture brain aneurysm.

·         Surgical clipping

·         Endovascular coiling

l . SURGICAL CLIPPING

·          Is a procedure to close of an aneurysm

·          The neurosurgeon removes a section of skull to access the aneurysm and locates the blood vessel that feeds the aneurysm.

·          A tiny metal clip is placed on the neck of the aneurysm to stop the blood flow to it

2. ENDOVASCOLAR THERAPY/ COILING

·          Is a less invasive procedure than surgical clipping

·          The surgeon inserts a hollow plastic tube (catheter) into an artery , then uses a guide wire to push a soft platinum wire through the catheter and into aneurysm

·          The wire coils up inside the aneurysm , disrupts the blood flow and causes blood to clot

·          This clotting essentially seals off the aneurysm from the artery.

Ventricular or lumbar draining catheters and shunt surgery

·          Can lessen pressure on the brain from excess cerebrospinal fluid (hydrocephalus) associated with a ruptured aneurysm

·          Catheter may be placed in the spaces filled with fluid inside of the brain (ventricles) or surrounding brain and spinal cord to drain the excess fluid into an external bag.

·          Shunt system — which consists of a flexible silicone rubber tube (shunt) and a valve — that creates a drainage channel starting in brain and ending in abdominal cavity.

Nursing management

·         Monitor neurologic status carefully everyhour

·          Establish and maintain a patent airway as needed. administer supplemental oxygen as ordered

·         Position the patient to promote pulmonary drainage and prevent upper airway obstruction. avoid placing the patient in the prone position as well as hyperextending his neck .

·         Suction the secretions from the airway as necessary to prevent hypoxia and vasodilation from carbondioxide accumulation

·         Prepare the patient for emergency craniotomy , if indicated

·         Administer hydralazine / antihypertensive agents as ordered.

·         Discourage and control any measures that initiates valsalvas maneuver, such as coughing , straining at stool , pushing up in bed with elbows , turning with the mouth closed.

·         Give fluids as ordered and monitor IV infusions to avoid overhydration, which may increase ICP.

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