Neuro Exam Notes: Stroke, TIA, Aneurysm, TBI, SCI, and Autonomic Dysreflexia

Ischemic vs. Hemorrhagic Stroke

  • Neurodegenerative diseases reviewed previously: MS, myasthenia gravis, Parkinson's, Huntington's, ALS, Guillain-Barré syndrome. Today focus on brain disorders acquired after birth (non-neurodegenerative) and how they affect brain function.
  • Stroke subtypes discussed: ischemic stroke and hemorrhagic stroke.
    • Ischemic stroke
    • Etiology: secondary to atherosclerosis; plaque buildup reduces cerebral perfusion distally; can progress to a thrombus that fully blocks perfusion to tissue downstream.
    • Significance: reduced blood flow leads to ischemia and potential infarction if perfusion remains blocked.
    • Hemorrhagic stroke
    • Etiology: due to an aneurysm formed by chronic hypertension; weakened arterial walls rupture, causing blood to leak into brain tissue.
    • Consequence: blood accumulates in intracranial space, compressing neural tissue and reducing distal perfusion, causing ischemia.
  • Transient Ischemic Attacks (TIAs)
    • Definition: very small, microscopic arterial ischemia producing transient symptoms lasting a short time (usually < 10 minutes, sometimes seconds).
    • Notable points from lecture:
    • TIAs can occur at any age; may be precursors to larger strokes if recurrent.
    • MRI can reveal tiny necrotic spots after frequent TIAs, indicating structural damage not captured by clinical stroke symptoms.
    • Brain tissue ischemia threshold: tissue becomes ischemic in about 4extminutes4 ext{ minutes} and total necrosis may occur around 9extminutes9 ext{ minutes} if perfusion isn’t restored.
    • Recovery: transient events may not cause lasting deficit unless TIAs recur and accumulate microscopic damage.
  • Aneurysms and drug-related risk factors
    • Aneurysm feature: a bulging, weakened arterial wall (often from sustained hypertension) that can rupture and cause hemorrhagic stroke.
    • AVMs: congenital arteriovenous malformations can burst and cause hemorrhage.
    • Cocaine use: induces severe vasoconstriction, increasing risk for aneurysm rupture and hemorrhagic stroke; vasoconstriction is not limited to cerebral arteries but can affect coronary and systemic vessels as well.
  • TIAs: clinical management and prevention emphasis
    • Acute management: elevate head position to reduce intracranial pressure (see below), titrate oxygen to maintain > 95 ext{%} (SpO2), and administer aspirin after ruling out intracranial bleeding.
    • Rationale: preventing progression to a full-blown stroke; TIAs serve as a warning sign for stroke risk.
  • Ischemic stroke management (emergency principles)
    • Time is critical: there is a therapeutic window for thrombolytics (e.g., tissue plasminogen activator, tPA) within about 4exthours4 ext{ hours} of initial symptoms.
    • Before thrombolysis: confirm ischemic mechanism (usually via imaging like MRI or CT) to rule out hemorrhage; giving thrombolytics in a hemorrhagic stroke can be catastrophic.
    • Thrombolytic agents: include tPA, TNK (tenecteplase), etc., depending on hospital protocol.
  • Signs and symptoms of acute stroke (vary by affected brain region)
    • Acute weakness on one side; neuropathy; sensory loss; facial droop; tinnitus/vertigo; visual disturbances (blurry vision, diplopia); altered level of consciousness; unilateral neglect.
    • Unilateral neglect: common with middle cerebral artery (MCA) stroke; patient ignores one side of the body/space.
    • Decussation concept: most cranial nerve fibers cross (about 80%) at the medulla; thus, a right-hemisphere (right-sided) stroke results in left-sided motor deficits.
  • Unilateral neglect: practical management
    • Approaches include:
    • Approach patient from the unaffected side so they can see you.
    • Teach scanning of the environment to perceive the full 180° visual field.
    • Rotate plates during meals so they see food on both sides; ensure they can eat safely.
    • Lighthouse strategy: caregiver/patient interaction begins from the unaffected side; the caregiver then sits on the affected side to engage the patient from the neglected side.
  • Homonymous hemianopsia
    • Definition: loss of half of the visual field in both eyes on the same side (e.g., left visual field loss from a right occipital/optic pathway stroke).
    • Impact: affects vision but not other senses; can influence driving eligibility and rehabilitation planning.
  • Acute stroke protocols and emergency department workflow
    • Time-sensitive care: EMS to ER codes stroke as a trauma alert; multiple teams prepare in advance.
    • Initial assessment: ABCs (airway, breathing, circulation); rapid neurological assessment and continuous vital signs monitoring; neuro status checked every 30 minutes initially, then every 4 hours for 72 hours.
    • Diagnostic steps: airway management if needed; ECG for atrial fibrillation; carotid ultrasound to assess stenosis; oxygen saturation targets; blood glucose target set around 140–180 mg/dL; head of bed elevated to 20–30° to reduce intracranial pressure; avoid hip flexion; stool softeners to avoid straining; antiemetics to prevent vomiting that can raise ICP.
    • Imaging before thrombolytics: always obtain brain imaging (MRI/CT) to distinguish ischemic vs hemorrhagic stroke.
  • Post-stroke planning and rehabilitation
    • Speech, occupational, and physical therapy are essential.
    • Nutrition and swallowing assessments are crucial to prevent aspiration; plan for safe feeding (e.g., aspiration risk assessment and speech therapy involvement).
  • Traumatic Brain Injury (TBI): mechanisms and management
    • Mechanisms of injury
    • Acceleration injury: head is moving; impact occurs; can cause brain to move within skull.
    • Deceleration injury: head is moving; impact with a fixed object; brain can bruise as it shifts.
    • Rotational injury: twisting forces cause shearing of axons; often severe.
    • Open head injury: skull is penetrated; direct exposure of brain to pathogens increases infection risk.
    • Closed head injury: skull intact but brain undergoes coup-contrecoup injuries or diffuse axonal injury.
    • Concussions: a type of TBI from jolt/shaking rather than direct impact; important in sports.
    • Initial management principles
    • Minimize brain stimulation for the first 72 hours to conserve energy for healing (quiet environment, limit lights and noise).
    • Maintain airway and adequate oxygenation; keep SpO2 high; neuro monitoring; monitor intracranial pressure (ICP).
    • Intracranial pressure and CSF dynamics
    • ICP normal range: 7extto15extmmHg7 ext{ to } 15 ext{ mmHg}.
    • Elevated ICP can compress brain tissue, impair perfusion, and promote ischemia and infarction.
    • When ICP rises, neurosurgery may place a ventriculostomy (e.g., a bolt) to measure ICP and drain CSF via a fourth-ventricle catheter to lower ICP.
    • Neurosurgical interventions and imaging
    • Craniotomy: temporarily remove part of the skull to relieve pressure.
    • EVD (external ventricular drain) and bolt monitoring are used to monitor and reduce ICP.
    • Pharmacologic and supportive care
    • Sodium management to control cerebral edema (hypertonic/hypernatremic strategies may be used).
    • Vigilance for increasing ICP signs (decreased consciousness, dilated pupils, new deficits).
  • Brain death and long-term prognosis in severe TBI
    • In severe cases, ventilatory support and sedation may be continued for diagnostic clarity and family discussion.
    • Brain death determination often involves a waiting period to observe inflammatory processes and ensure no residual brain activity; family discussions about prognosis are challenging but essential.
  • Spinal Cord Injury (SCI): types and early management
    • Complete SCI
    • No impulses travel from brain to peripheral nervous system below injury level; destruction of voluntary movement and sensation; reflexes lost below the lesion.
    • Incomplete SCI
    • Some tracts remain intact and may carry impulses; some function preserved.
    • Acute management principles
    • Immobilize the spine on arrival; rapid assessment for other injuries; transport to ED.
    • Cervical spine stabilization (backboard, collar); halo traction may be used for neck stabilization and gradual healing.
    • Complications and long-term concerns
    • Pressure ulcer risk due to loss of sensation and prolonged immobility; reposition every two hours.
    • Thrombosis and pulmonary embolism risk due to immobility; DVT prophylaxis may be indicated.
    • Respiratory compromise with high cervical injuries due to diaphragmatic paralysis and decreased respiratory muscle control; C3–C5 are classically critical for breathing in true anatomy, but the lecture notes mention C6 in relation to the diaphragm.
    • Neurogenic bladder and bowel dysfunction requiring intermittently or straight catheterization and bowel/bladder training.
    • Sexual dysfunction assessment.
  • Autonomic dysreflexia (AD)
    • Definition: a potentially life-threatening spike in blood pressure in patients with SCI above T6 due to loss of autonomic regulation and a trigger below the injury level (e.g., bladder distension, full rectum, skin irritation).
    • Clinical and practical considerations
    • AD can be triggered by various stimuli; the injury level must be known (above T6 is high risk).
    • Immediate response involves identifying and removing triggers, rapid assessment, and pharmacologic BP management (e.g., intravenous vasodilators such as prazosine or other agents used per protocol; the lecture mentions amanzoline and slow IV administration—note the specific drug naming from the lecture may be nonstandard).
    • Chart labeling and communication of triggers are vital for safe care.
  • Practical nursing and patient education themes from the lecture
    • Time-critical nature of stroke care and the need for rapid evaluation and imaging.
    • Importance of neuro checks and monitoring in acute settings (30-minute checks initially, then every 4 hours for 72 hours).
    • Understanding the signs of stroke helps guide immediate interventions, rehabilitation planning, and patient/family education.
    • Emphasis on preventative health measures to reduce stroke risk (modifiable risk factors: blood pressure, smoking, obesity, physical activity, glycemic control).
  • Key numerical references and formulas used in the lecture
    • Ischemia timing thresholds:
    • Ischemia occurs within 4extminutes4 ext{ minutes} of sustained ischemia; infarction may occur by about 9extminutes9 ext{ minutes} if perfusion is not restored. t<em>extischemia=4extmin, t</em>extnecrosis=9extmint<em>{ ext{ischemia}} = 4 ext{ min}, \, t</em>{ ext{necrosis}} = 9 ext{ min}
    • Intracranial pressure (ICP) normal range:
    • 7extto15extmmHg7 ext{ to } 15 ext{ mmHg}
    • Thrombolysis window for ischemic stroke:
    • Within 4exthours4 ext{ hours} of initial signs/symptoms
    • Oxygenation targets:
    • SpO2 > 95 ext{%} (often stated as > 94-95% in some protocols)
    • Blood pressure and perfusion targets in head injury/stroke care:
    • SBP should be > 100extmmHg100 ext{ mmHg} for adequate cerebral perfusion
    • Glucose targets during acute stroke management:
    • 140extto180extmg/dL140 ext{ to } 180 ext{ mg/dL}
  • Connections to broader clinical principles
    • The content reinforces foundational neuroanatomy concepts (e.g., decussation of motor pathways, MCA predominance in strokes) and links them to clinical signs (unilateral weakness, neglect, homonymous hemianopsia).
    • Emphasizes the integration of acute management, diagnostic imaging, prevention of further injury, and multidisciplinary rehabilitation.
    • Highlights ethical and practical dimensions in TBI and SCI care, including family communication, uncertainty of prognosis, and the balance between aggressive intervention and quality of life.
  • Quick review pointers for exam-style questions
    • Distinguish ischemic vs hemorrhagic stroke by imaging before giving thrombolytics.
    • Remember typical signs that map to brain regions (e.g., MCA stroke and unilateral neglect, homonymous hemianopsia).
    • TIAs are warning signs; educate patients about risk modification and prevention of full stroke.
    • For SCI, differentiate spinal shock (transient) from neurogenic shock (autonomic dysfunction) and recognize AD above T6.
    • ICP management basics: monitor signs of rising ICP, keep head midline and elevated, avoid actions that increase ICP, and be prepared for interventions like a ventriculostomy or craniotomy when indicated.
  • Ethical and practical implications discussed
    • The difficulty of predicting outcomes after TBI and the caution required when communicating prognosis to families.
    • The necessity of rapid, evidence-based action in stroke to minimize disability, balanced with risks of thrombolysis in uncertain cases.
    • The importance of preventing secondary injury in SCI and TBI through careful monitoring, minimizing stimulation, and preventing complications like ulcers, DVT, and autonomic dysreflexia.
  • Summary of key terms to know for exams
    • Ischemic stroke, hemorrhagic stroke, TIAs, MCA, aneurysm, AVMs, TPA/tenecteplase, hypoxic-ischemic injury, unilateral neglect, homonymous hemianopsia, ICP, craniotomy, ventriculostomy, cranial bolt, open vs closed head injury, concussion, spinal shock, neurogenic shock, autonomic dysreflexia, halo traction, pressure ulcers, dignified family communication in prognosis