Cerebrovascular Events: TIA and Stroke

• Cerebrovascular events are also known as strokes or TIAs.

Transient Ischemic Attack (TIA)

• TIA is a short-term interruption in blood flow to the brain.
• This interruption resolves within 24 hours and leaves no residual brain damage.
• TIA is considered a major warning sign for stroke risk.

Stroke (Cerebrovascular Accident)

• Stroke involves an interruption of blood circulation to the brain.
• Neurologic deficits result that correspond to the affected brain area.
• Strokes can be ischemic, which is more common, or hemorrhagic which is more deadly.
• Stroke is the 5th leading cause of death, improved from being the 3rd leading cause.
• Management has significantly improved outcomes.
• African American males and females have twice the likelihood of stroke and higher mortality than other races.
• The cost of stroke is about $36.5 billion annually.
• 15% to 30% of stroke survivors are permanently disabled, placing a large burden on long-term care facilities.

Epidemiology

• Annually, there are more than 795,000 strokes in the U.S.
• Someone in the U.S. has a stroke approximately every 40 seconds.
• More than 133,000 deaths per year are attributed to stroke.
• Stroke is more disabling than fatal, and it is the leading cause of serious long-term disability.
• 6.1 million Americans, aged 20 and older, have had a stroke.
• It's estimated that 58% of Americans are unaware they are at risk.
• 40% of stroke deaths occur in males, and 60% occur in females.
• A significant racial disparity exists.
• 80% of strokes can be prevented.

Risk Factors

• Ischemic strokes tend to occur in older patients with co-morbidities.
• Risk factors for ischemic stroke include hypertension, older age, cigarette smoking, male gender, family history, race, previous stroke or TIA, carotid stenosis of more than 80%, atrial fibrillation, and drug abuse.
• Additional factors include diabetes, obesity, sedentary lifestyle, and hyperlipidemia.
• Hemorrhagic strokes tend to occur in healthy individuals between the ages of 40 and 60 years.
• Risk factors for hemorrhagic stroke include uncontrolled hypertension, smoking, hyperlipidemia, obesity, diabetes, heart disease, family history of stroke, use of blood thinners, arteriovenous malformations, trauma, and aneurysms.

Pathophysiology of TIA

• Narrowing of a major artery reduces blood flow to the brain, such as the carotid artery.
• An embolus travels to the brain from another part of the body, temporarily occluding blood flow.
• Plaque accumulation in a brain artery decreases blood flow.

Pathophysiology of Ischemic Stroke

• Thrombotic strokes involve atherosclerotic build-up, resulting in a complete blockage of an artery.
• Embolic strokes involve a clot that lodges and creates a blockage of blood flow.
• The effect of the blockage depends on the severity and length of ischemia, as well as the location in the brain.
• The longer the time, the larger the area of cell death and the greater the swelling.

Pathophysiology of Subarachnoid Hemorrhage

• Bleeding occurs between the tissue that covers the brain and the brain itself.
• An aneurysm, arteriovenous (AV) malformation, or bleeding disorder usually causes it.
• Both of subarachnoid and intracerebral Hemorrhage events cause the area surrounding the injury dies due to lack of O2 and ATP pathway failure.
• Intracellular calcium release contributes to cell death.

Pathophysiology of Intracerebral Hemorrhage

• Bleeding occurs within the brain tissue itself.
• A weakened artery in the brain with uncontrolled hypertension is the primary factor in intracerebral Hemorrhage.

Clinical Presentation

• TIA and ischemic strokes may have similar presentations.
• Symptoms of both TIA and ischemic strokes tend to worsen over time.
• Acronym FAST aids the recognition of stroke. It includes face drooping, arm weakness, speech difficulty and time to call 911.

Subarachnoid Hemorrhage

• Headache in subarachnoid hemorrhage is described as the "worst of my life."
• Nausea and vomiting may occur due to meningeal irritation.
• Varying degrees of neurological dysfunction can be seen.
• Short term LOC could occur.
• Atypical headaches in the days or week which precede the event.
• May cause occasional seizures.

Intracerebral Hemorrhage

• Intracerebral hemorrhage may present as a headache.
• Symptoms of intracerebral hemorrhage could include facial sag, slurred speech, limb weakness and eye deviation away from affected limbs within 5-30 minutes.
• There may be no consistent prodromal symptoms.
• Onset while sleeping is rare.
• Hypertension is almost always present.
• Clinical presentation depends on the location and severity of the bleed;
• Immediate coma or stupor could occur.
• Hemiplegia that worsens in minutes to hours.

Physical Exam

• Physical examination findings correspond to the location of the vascular event and associated neurologic deficits.
• Emphasis placed on a patent and protected airway, quality respiratory effort, heart rate and peripheral circulation (ABC's).
• Neurologic deficits assessment quickly follows.

ABCD Score

• The ABCD score is used for cerebral vascular syndrome risk assessment.

Criteria

• Age ≥60 years gets 1 point.
• Blood pressure ≥140 mm Hg systolic and/or ≥90 mm Hg diastolic gets 1 point.
• Unilateral weakness with/without speech changes gets 2 points.
• Speech changes, no unilateral weakness gets 1 point.
• Duration ≥60 minutes gets 2 points.
• Duration ≤59 minutes gets 1 point.
• Diabetes gets 1 point

Interpretation

• A score of 1-3 points shows a 1% risk, consider scheduling neurology consultation for possible outpatient treatment/evaluation.
• A score of 4-5 points shows a 4.1% risk, hospitalization is justified.
• A score of 6-7 points shows a 8.1% risk, hospitalization is beneficial.

Diagnostics

• Head CT (non-contrast) is preferrable to distinguish the type of stroke
• If there is an atypical presentation, consider CT with contrast or MRI to rule out tumors.
• Other diagnostic modalities include EKG, ABG, CBC, PT, PTT, CMP, EEG and Carotid Ultrasound.

Differentials for Cerebrovascular Events

• Other Neurologic etiologies could include migraine, seizures, subdural or epidural hematoma, tumor (primary/metastatic), syncope, transient global amnesia, and encephalopathy.
• Cardiac arrest (Post-Cardiac Arrest Ischemia) could cause similar symptoms via cardiac arrhythmia, transient global amnesia and encephalopathy.
• Metabolic disorders such as hypoglycemia and nonketotic hyperosmolar coma.
• Psychiatric disorders such as conversion disorder, hyperventilation, and panic attack.
• Drug overdose from cocaine or amphetamine.
• Infection (meningitis/encephalitis).
• Immunologic disorders such as demyelinating syndromes.

Management

• Immediate emergency room referral is required for all patients with suspected cerebrovascular events.
• Initial management varies depending on the presentation.
• Risk management is a primary factor for all patients.
• ABCD score is helpful.
• Patients confirmed to have had TIA can be treated as outpatients.
• Time is of the essence for all suspected strokes.

Stroke Centers Levels

• Acute stroke ready hospitals are in development.
• These will have trained stroke response teams available in the ER and standard care protocols.
• These hospitals administer thrombolytics based on existing protocols.
• These hospitals use telemedicine for rapid consultation with neurologists.
• Patients will be rapidly transferred to tertiary facilities when needed.
• Primary Stroke Centers are accredited and measure the time from patient arrival to thrombolytics administration.
• Patients will undergo accepted treatment algorithms.
• Comprehensive Stroke Centers have neurosurgeons, neurologists, neurologic intensive care units, interventional radiologists, and extensive rehabilitation services.
• These centers support acute stroke-ready hospitals and primary stroke centers through education, streamlined transfer, and acute specialized treatment.
• ER management includes CT scan, ABC maintenance, airway management, neurology consult, and monitoring blood pressure.
• Oral antihypertensive agents are preferred, to avoid excessively rapid blood pressure reduction.
• TPA was approved in 1996 for ischemic stroke patients if the drug gets administered to the patient 3hrs from the stroke.
• Revisions in 2009 increased the time frame to 4.5 hours, except for those on anti-coagulants, with diabetes, a history of stroke, or older than 80 years.
• Surgical interventions could be performed in the event of a stroke.
• Carotid endarterectomy.
• Coil placed by interventional radiology into aneurysm.
• Ventriculostomy to reduce intracranial pressure.

Patient Education

• Focus is on risk reduction and stroke symptom recognition and emergency treatment.

Modifiable Risk Factors

• Hypertension
• Smoking
• Diabetes
• Atrial Fibrillation
• Hyperlipidemia
• Sedentary Lifestyle
• Carotid Artery Disease
• Obesity

Non-Modifiable Risk Factors

• Increased age
• Family history
• Race (African Americans and Hispanics have higher incidence) -Gender (men have a higher incidence, while women have higher mortality).