Cerebral Aneurysm Notes

Cerebral Aneurysm

Overview

• Cerebral aneurysms are bulges or balloon-like dilatations in the walls of blood vessels (arteries) in the brain.

Objectives

• Understand the physiology of cerebral aneurysms.
• Explain the types and causes of cerebral aneurysms.
• Understand the treatment of cerebral aneurysms.
• Describe the nursing management of patients with cerebral aneurysms.

Central Nervous System (CNS)

• Brain:
  • Receives and processes sensory information.
  • Initiates responses.
  • Stores memories.
  • Generates thoughts and emotions.
• Spinal Cord:
  • Conducts signals to and from the brain.
  • Controls reflex activities.

Peripheral Nervous System (PNS)

• Sensory Neurons:
  • Sensory organs to CNS.
• Motor Neurons:
  • CNS to muscles and glands.
  • Somatic Nervous System: Controls voluntary movements.
  • Autonomic Nervous System: Controls involuntary responses.
    • Sympathetic Division: "Fight or Flight".
    • Parasympathetic Division: "Rest or Digest".

Brain Lobes and Functions

• Frontal Lobe:
  • Motor control (premotor cortex).
  • Problem-solving (prefrontal area).
  • Speech production (Broca's area).
• Parietal Lobe:
  • Touch perception (somatosensory cortex).
  • Body orientation and sensory discrimination.
• Temporal Lobe:
  • Auditory processing (hearing).
  • Language comprehension (Wernicke's area).
  • Memory/information retrieval.
• Occipital Lobe:
  • Sight (visual cortex).
  • Visual reception and visual interpretation.
• Brainstem:
  • Involuntary responses.
• Cerebellum:
  • Balance and coordination.

Cerebral Aneurysm Defined

• A bulge or balloon-like dilation/swelling of the wall of a blood vessel in the brain.
• Develops due to weakness in the vessel wall, usually at branch points.

Blood Supply to the Brain

• Blood is supplied to the brain by four major blood vessels that join together, forming the Circle of Willis at the base of the brain:
  1. Anterior cerebral artery.
  2. Posterior cerebral artery.
  3. Internal carotid artery.
  4. Basilar artery.

Circle of Willis

• The circle of Willis begins to form when the right and left internal carotid arteries (ICA) enter the cranial cavity, each dividing into two main branches: the anterior cerebral artery (ACA) and the middle cerebral artery (MCA).
• The anterior cerebral arteries are united, allowing blood to cross-flow via the anterior communicating (ACOM) artery.
• The ACAs supply most midline portions of the frontal lobes and superior medial parietal lobes.
• The MCAs supply most of the lateral surface of the hemisphere, except the superior portion of the parietal lobe (via ACA) and the inferior portion of the temporal lobe and occipital lobe.
• The ACAs, ACOM, and MCAs form the anterior half, known as the anterior cerebral circulation.
• Posteriorly, the basilar artery (BA), formed by the left and right vertebral arteries, branches into left and right posterior cerebral arteries (PCA), forming the posterior circulation.
• The PCAs mostly supply blood to the occipital lobe and inferior portion of the temporal lobe.

Layers of Blood Vessel

• Tunica intima (Endothelium)
• Internal elastic membrane
• Tunica media (Smooth muscle)
• External elastic membrane
• Tunica externa

Pathophysiology of Intracranial Aneurysm

• Normal Cerebral Vessel:
  • VSMC (Vascular Smooth Muscle Cells) dysfunction.
  • Environmental factors (Cigarette smoking, Genetics, Wall shear stress).
  • Pro-inflammatory VSMCs lead to an inflammatory response (Macrophages, mast cells, T cells).
  • Endothelial cell dysfunction (NF-kB, Ets, PGE2, MCP-1).
  • Aneurysm formation and progression leading to rupture.

Types of Cerebral Aneurysms

• Saccular Aneurysm
• Fusiform Aneurysm
• Ruptured Aneurysm
• Dissecting

Why Aneurysms Develop

• In many cases, the cause is unknown (idiopathic).
• Potential factors include:
  1. Congenital or familial inheritance
  2. Atherosclerosis
  3. Hypertension
  4. Connective tissue disorders
  5. Sickle cell anemia
  6. Infections
  7. Trauma
  8. Cigarette smoking
  9. Illicit drug use
  10. Alcohol

Who Gets Aneurysms?

• Peak incidence: 40-60 years old.
• Rare in children.
• Female predominance in adults.

Symptoms of Cerebral Aneurysm

• Headache: Acute onset of severe pain, described as "the worst headache of my life."
• Facial pain.
• Manifestations of meningeal irritation: Neck pain or stiffness.
• Alterations in consciousness: Sudden elevation of ICP may lead to a severe decline in cerebral perfusion pressure, causing syncope (50% of cases). Confusion or mild impairment in alertness may also be noted.
• Seizures: Present in 25% of aneurysmal SAH cases, with most events occurring within 24 hours of onset.
• Autonomic disturbances: Subarachnoid accumulation of blood degradation products may elicit fever. Nausea or vomiting, sweating, chills, and cardiac arrhythmias may also be present.
• Visual symptoms: Blurring of vision, diplopia, or visual field defects may be present.

Ruptured Aneurysm Symptoms

• Sudden and extremely severe headache (e.g., the worst headache of one’s life).
• Double vision.
• Nausea.
• Vomiting.
• Nuchal rigidity.
• Photosensitivity (sensitivity to light).
• Seizures.
• Loss of consciousness (brief or prolonged).
• Cardiac arrest.

Diagnosis of Brain Aneurysm

1. History of the Headache: Acute onset of the worst headache of the patient's life, associated with a stiff neck.
2. CT-Scan & MRI: Shows a subarachnoid hemorrhage in more than 90% of cases of ruptured aneurysm.
3. Lumbar Puncture:
   • Considered if CT results are negative but there is a strong clinical suspicion of SAH.
   • Identifies blood in the cerebrospinal fluid (CSF) in the subarachnoid space.
4. Cerebrospinal Fluid Analysis:
   • Bloody CSF that fails to clear with continued egress of CSF suggests SAH.
   • Presence of xanthochromia (yellowish discoloration) indicates bilirubin from hemoglobin breakdown.
   • Xanthochromic CSF indicates SAH occurred more than 12 hours prior; fresh blood suggests trauma.
5. Computed Tomography (CT):
   • Reliable and simple diagnostic test for ruptured aneurysm.
   • Positivity rate is 98-100% up to 12 hours after onset and 93% in the first 24 hours.
   • Positive results decrease with time.
   • Findings: Well-defined round hyperattenuating lesions.
6. Cerebral Angiography:
   • Widely used modality for imaging and screening intracranial aneurysms.
   • 100ml of contrast medium is injected intravenously at a flow rate of 4ml/sec.
   • Changes in attenuation values are measured with a region of interest with the internal carotid arteries, and spinal scan is automatically started.

Intra-arterial Digital Subtraction Angiography (IADSA)

• Most sensitive tool for detecting intracranial aneurysms.
• Should be performed within 24 hours from bleeding.
• Demonstrates the aneurysm's neck, size, location, associated cortical branches, vasospasm, and additional aneurysms.
• Performed with selective injection of ICA and vertebral arteries to investigate the entire cerebral vasculature.

Fisher's Grade - SAH

Complications of Aneurysm Rupture

• Re-rupture, rebleeding
• Cerebral vasospasm
• Delayed ischemic complications and stroke
• Hydrocephalus
• Seizures
• Central nervous system infections
• Volume disturbances
• Osmolar disturbances
• Cerebral sodium depletion
• SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion
• Pulmonary edema
• Cardiac arrhythmias
• Takotsubo cardiomyopathy

Management Aims

• Allow the brain to recover from the initial insult (bleeding).
• Prevent or treat other complications, especially vasospasm.

Management Strategies

• Surgical (Clipping, Coiling)
• Medical (Medication)

Surgical Management

• Clipping:
  • A neurosurgeon cuts open the skull, identifies the damaged blood vessel, and puts a clip across the aneurysm neck.
  • This prevents blood from entering the aneurysm and causing further growth or blood leakage.
• Coiling:
  • A neurosurgeon or interventional radiologist threads a tube through the arteries, identifies the aneurysm, and fills it with coils of platinum wire or latex.
  • This prevents further blood from entering the aneurysm.
• Flow Diversion
  • Bridges the aneurysm neck and diverts blood flow away from the aneurysm sac.
  • Reduction of blood flow into the aneurysmal sac causes stasis, thrombosis, and healing of the aneurysm.

Medical Management

• Calcium channel blockers: Nimodipine (Nimotop), Verapamil (Isoptin).
• Osmotic diuretic: Mannitol 20%.
• Antiepileptics: Phenytoin.
• Antihypertensives: Nitroprusside.
• Antifibrinolytic agents (if surgery is delayed or contraindicated).
• Analgesics: Acetaminophen.
• Laxatives: To prevent straining and avoid BP increase.
• Elastic stockings: to prevent DVT.

Nursing Management

• Nursing Assessment:
  • Altered level of consciousness.
  • Sluggish pupillary reaction.
  • Motor and sensory dysfunction.
  • Cranial nerve deficits (extraocular eye movements, facial droop, ptosis).
  • Speech difficulties and visual disturbance.
  • Headache and nuchal rigidity or other neurologic deficits.
• Nursing Diagnosis:
  • Ineffective tissue perfusion related to bleeding or vasospasm.
  • Impaired Physical Mobility related to weakness, paraesthesia.
  • Impaired verbal communication related to impaired cerebral circulation.
  • Disturbed sensory perception related to altered sensory reception, transmission, integration.
  • Self-care deficit related to neuromuscular impairment.
  • Risk for impaired swallowing related to neuromuscular impairment.
• Improving Cerebral Tissue Perfusion:
  • Monitor closely for neurologic deterioration.
  • Check blood pressure, pulse, level of consciousness, pupillary responses, and motor function hourly; monitor respiratory status.
  • Implement aneurysm precautions (immediate and absolute bed rest in a quiet, nonstressful setting; restrict visitors).
  • Elevate the head of bed 15 to 30 degrees or as ordered.
  • Avoid any activity that suddenly increases blood pressure or obstructs venous return (e.g., Valsalva maneuver, straining).
  • Apply antiembolism stockings or sequential compression devices. Observe legs for signs and symptoms of deep vein thrombosis (tenderness, redness, swelling, warmth, and edema).
• Relieving Sensory Perception:
  • Keep sensory stimulation to a minimum.
  • Explain restrictions to help reduce the patient’s sense of isolation.
• Relieving Anxiety:
  • Inform the patient of the plan of care.
  • Provide support and appropriate reassurance to the patient and family.
• Monitoring and Managing Complications:
  • Assess for and immediately report signs of possible vasospasm, and administer calcium channel blockers or fluid volume expanders as prescribed.
  • Maintain seizure precautions and maintain airway and prevent injury if a seizure occurs. Administer antiseizure medications as prescribed (phenytoin).
  • Monitor for onset of symptoms of hydrocephalus.
  • Monitor for and report symptoms of aneurysm rebleeding. Rebleeding occurs most often in the first 2 weeks (sudden severe headache, nausea, vomiting, decreased level of consciousness, and neurologic deficit).
  • Administer medications as ordered.
  • Hyponatremia: monitor sodium level.
• Discharge and Home Care Guidelines:
  • Teach patients and family members about the disease condition.
  • Explain medical treatments, assistive devices, and the importance of follow-up appointments.

Hyponatremia

• A common complication following a brain aneurysm and subarachnoid hemorrhage (SAH).
• Occurs in up to 40-50% of patients.
• Can be due to SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion) or cerebral salt-wasting syndrome (CSWS).
• Hyponatremia can exacerbate complications like cerebral edema and increase intracranial pressure, potentially worsening patient outcomes.
• SIADH is a condition where the body produces too much antidiuretic hormone (ADH), also known as vasopressin, even when serum osmolality is low. This excess ADH leads to increased water retention and dilution of sodium, resulting in hyponatremia.

Summary of Nursing Care

• Nursing care for brain aneurysms focuses on monitoring for complications, managing neurological status, and providing psychosocial support to patients and their families.
• Includes meticulous observation of vital signs, neurological function, and any signs of aneurysm rupture or other complications.
• Nurses educate patients and families about the condition, treatment options, and post-operative care.

Pre-operative Care

• Neurological Assessment:
  • Regular assessment of neurological status, including level of consciousness, pupillary response, motor function, and sensory function, is essential to identify any changes or deterioration.
• Blood Pressure Management:
  • Strict blood pressure control is crucial, as high blood pressure can increase the risk of aneurysm rupture.
• Hydration and Electrolyte Balance:
  • Maintaining adequate hydration and electrolyte balance is vital to prevent complications.
• Patient Education:
  • Explaining the procedure, potential risks and benefits, and post-operative care instructions is important.

Post-operative Care

• Monitoring for Rupture:
  • Close monitoring for signs of aneurysm rupture, such as sudden severe headache, vomiting, and neurological deficits, is critical.
• Intracranial Pressure (ICP) Management:
  • Monitoring and managing ICP is essential to prevent secondary brain injury.
• Vital Sign Monitoring:
  • Continuous monitoring of vital signs, including heart rate, respiratory rate, blood pressure, and oxygen saturation, is necessary.
• Pain Management:
  • Effective pain management is crucial for patient comfort and to prevent complications.
• Prophylaxis against Complications:
  • Measures to prevent deep vein thrombosis, pressure ulcers, and infections should be implemented.
• Psychosocial Support:
  • Providing emotional support, counseling, and education to the patient and family is essential to address anxiety and facilitate coping.
• Rehabilitation:
  • Assisting with physical, occupational, and speech therapy to promote recovery and improve functional outcomes.
• Medication Management:
  • Educating patients about medication management, including anti-platelet agents and medications for managing pain, seizures, or vasospasm.
• Follow-up Care:
  • Explaining the importance of regular follow-up appointments and imaging studies to monitor for recurrence or other complications.

Specific Nursing Interventions

• Elevate Head of Bed: This helps to reduce ICP.
• Maintain Adequate Oxygenation: Ensuring sufficient oxygenation is crucial for brain tissue health.
• Administer Medications: Administering medications as prescribed, such as anti-seizure medications, pain relievers, and anti-hypertensives.
• Provide Fluid and Electrolyte Balance: Monitoring and managing fluid and electrolyte balance to prevent complications.
• Monitor for Signs of Vasospasm: Recognizing and managing vasospasm, which can occur after aneurysm rupture, is essential.
• Encourage Early Mobility: Promoting early mobilization and activity to prevent complications like deep vein thrombosis.
• Educate Patients on Lifestyle Modifications: Advise on lifestyle changes, such as quitting smoking, managing hypertension, and maintaining a healthy weight.