Neuropathology of Strokes

Stroke

• Stroke is a brain injury caused by a disruption to blood vessels in the brain, leading to neurological dysfunction.
• Strokes are the third leading cause of death in the US and are responsible for about half of all aphasia cases.
• The lack of blood supply to the brain (ischemia) leads to brain cell death, resulting in a stroke.
• 87% of strokes are ischemic, caused by blockages in the arteries supplying blood to the brain.
• 13% of strokes are hemorrhagic, caused by ruptured blood vessels that bleed into the brain tissue or surrounding spaces.
• Stroke symptoms include weakness, numbness, impaired vision, difficulty speaking/understanding, balance issues, severe headache, nausea, and vomiting.
• The location and extent of the stroke, as well as the amount of brain tissue damage, determine the severity of the stroke.
• Prompt medical attention is crucial to minimize brain damage, as the brain can sustain irreversible damage within 3 minutes of oxygen deprivation.

Ischemic Strokes

• Ischemic strokes are more common than hemorrhagic strokes, accounting for 87% of cases.
• Thrombotic strokes are caused by a blood clot that forms in the arteries supplying the brain.
• Embolic strokes are caused by a piece of debris (emboli) that travels through the bloodstream and blocks an artery in the brain.

Hemorrhagic Strokes

• Hemorrhagic strokes occur when a weakened blood vessel ruptures and bleeds into the brain tissue or surrounding spaces.
• Common causes of hemorrhagic strokes include high blood pressure, aneurysms, and arteriovenous malformations (AVMs).
• Aneurysms are weakened sections of an arterial wall that can balloon out and rupture, leading to bleeding.
• AVMs are incorrect formations of blood vessels in the brain, where arteries and veins connect directly, bypassing normal tissues.
• Hemorrhagic strokes can be extremely deadly and often lead to severe disability or death.

Transient Ischemic Attacks (TIA)

• TIAs are temporary disruptions of cerebral circulation lasting less than 24 hours.
• Symptoms are similar to stroke but do not last as long and do not cause permanent brain damage.
• TIAs are a warning sign of underlying cerebrovascular disease and can indicate an increased risk of future stroke.

Stroke Prevention

• 80% of strokes are preventable by managing risk factors, including high blood pressure, smoking, atrial fibrillation, and physical inactivity.
• High blood pressure is the most important risk factor to control, as it is responsible for more than half of all strokes.

Stroke Recovery

• Language recovery after stroke is greatest in the first three months.
• Most stroke recovery occurs within the first 6-8 months after the event.
• Ischemic stroke recovery is usually more rapid than hemorrhagic stroke recovery.

Stroke

• Stroke occurs when a blood vessel in the brain is blocked or ruptures
• Medical treatments aim to open blocked vessels or treat ruptures
• Survival rates have significantly improved due to advancements in stroke treatments

Treatment Options

• Anticoagulants/Antiplatelets
  • Prevent blood clotting
  • Examples include aspirin and warfarin
• Antihypertensives
  • Treat high blood pressure
  • Lower blood pressure by opening blood vessels, decreasing blood volume or reducing the heart's pumping rate and force

Ischemic Stroke Treatment

• Tissue plasminogen activator (tPA)
  • The only FDA-approved treatment for ischemic strokes
  • Dissolves clots and improves blood flow
  • Must be administered within 3 hours (up to 4.5 hours for certain eligible patients)
  • Significant number of victims don't reach the hospital in time for tPA treatment

Mechanical Thrombectomy

• Endovascular procedure for removing large blood clots
• Doctors use a stent retriever, a wired-caged device, to reach the blocked blood vessel
• Procedure should be done within 6 hours of stroke symptoms, after tPA administration

Hemorrhagic Stroke Treatment

• Endovascular Procedures
  • Similar to those used for ischemic strokes
  • Less invasive than surgical treatments
  • Involve guiding a catheter to the aneurysm or AVM and depositing a mechanical agent (coil) to prevent rupture
• Surgical Treatment
  • Used for bleeds within the brain or abnormal blood vessel tangles (AVMs)
  • May involve clipping the base of a ruptured aneurysm to secure it

Associated Medical Conditions

• Diabetes (IDDM/NIDDM)
  • Elevated blood sugar speeds up arteriosclerosis
• Hypertension
  • Persistently high blood pressure
• Obesity
  • Abnormal fat accumulation
• High Cholesterol
  • Development of plaques
• Arteriosclerosis
  • Loss of elasticity, thickening or hardening of the arteries
• Atrial Fibrillation (A-Fib)
  • Heart palpitations
• Hydrocephalus
  • Build-up of fluid in the skull, causing brain swelling
• Infections
  • Bacterial meningitis
  • Brain abscess
• Smoking
  • Narrows blood vessels
• Drug abuse
• Lack of exercise

Causes of Cognitive-Linguistic Deficit and Aphasia Syndromes

• Traumatic Brain Injury (TBI)
  • Second leading cause of aphasia
  • Can result in speech-language disorders
  • Anomic aphasia is common
• Seizures
  • Abnormal neural discharge
  • Can cause various neurological issues, including aphasia
  • May impact aphasia recovery
• Tumors
  • Brain tumors (glioblastomas)
  • Tumors in tissues near the brain (meningiomas)
  • Cause anomia, word finding difficulty
  • Increased intracranial pressure can cause confusion and drowsiness

Dementia

• Progressive decline in cognitive function
• Aphasia develops with classical aphasia patterns
• Eventually progresses from palilalia to mutism

Neuropathology of Aphasia

• Language disorder resulting from brain damage
• Different aphasia syndromes stem from specific blood vessel involvement and various disease causes
• Recovery rates and patterns vary depending on the affected areas
• Dominant hemisphere (usually left) is responsible for language
• 95% of right-handers have left hemisphere dominance for language
• Approximately 70% of left-handers have right hemisphere dominance, while 30% have bilateral dominance

Broca’s and Wernicke’s Aphasia

• Broca’s aphasia
  • Lesion in the left lateral, frontal, prerolandic, suprasylvian region
  • Superior division of MCA
  • Affects speech production
• Wernicke’s aphasia
  • Lesion in the posterior third of the superior temporal gyrus, inferior MCA
  • Affects language comprehension

Conduction and Anomic Aphasia

• Conduction aphasia
  • Lesion in the supramarginal gyrus and white matter pathways connecting Wernicke's and Broca’s areas
  • Affects repetition
• Anomic aphasia
  • Lesion in or near language zones
  • Affects word finding

Transcortical Motor & Sensory Aphasia

• Transcortical Motor aphasia
  • Lesion interrupts the connection between the supplementary motor cortex and Broca’s area
  • Impacts speech fluency
• Transcortical Sensory aphasia
  • Posterior lesion at the border of middle and posterior cerebral arteries
  • Affects language comprehension

Global Aphasia

• Destruction of large portions of the left fronto-parieto-temporal zone of language
• Severe language deficits across all modalities

Global Subcortical Aphasias

• Severe language deficit across all modalities
• Milder version - mixed aphasia
• Subcortical aphasias - two primary locations: basal ganglia and internal capsule, or thalamus

This quiz explores the causes and effects of strokes, focusing on the types, symptoms, and urgency of medical attention required. Learn about ischemic and hemorrhagic strokes and their impact on brain health. Test your knowledge on how strokes can lead to various neurological dysfunctions.