Stroke

• Neurodegenerative disorders


  Progressive damage or death of neurons leading to a gradual deterioration of the bodily functions controlled by the affected part of the nervous system
• Types of neurodegenerative disorders

  • Acute (e.g. Stroke)
  • Chronic (e.g. Alzheimer's Disease, Parkinson's Disease, Huntington's Chorea)
• Brain damage


  Leads to the death or degeneration of neurons
• Causes of brain damage

  • Genetics
  • Trauma
  • Tumour
  • Alterations in blood flow

  
• Cerebral stroke


  Blockage/interruption of cerebral artery leading to death of cells
• Cerebral stroke


  • Symptoms depend on location
  • Prevalence in the UK: 250-400 strokes per 100,000 people, 3rd cause of death, 1st cause of disability in adults
• Types of stroke


  • Ischemic (80%)
  • Haemorrhagic (20%)
• Risk factors for stroke

  • Hypertension
  • Diabetes
  • Cardiac disease
  • Hyperlipidaemia
  • Smoking
  • Family history
  • Obesity
  • Diet
  • Oral contraceptive pill
  • Previous stroke
• Clinical symptoms of stroke

  • Sudden or gradual onset
  • One-sided limb weakness/paralysis
  • Confusion, loss of speech/vision
  • Headache
  • Loss of consciousness

  
• Cognitive impairment after stroke


  Amnesia, inattention, confusion, depression, mood and behaviour changes
• Post-stroke depression


  More cognitive impairment, irritability, psychomotor slowing, mood liability compared to primary depression
• Transient ischemic attack (TIA)


  Transient episode of neurological dysfunction without acute tissue death, disruption of cerebral blood flow, mini-strokes, risk factor for subsequent stroke, 10% strokes within 90 days of TIA, silent strokes with no visible symptoms
• Ischemic stroke - core and penumbra

  Core = blood flow below critical, cell death, penumbra = sub-optimal blood flow, potentially salvageable
• Cause of cell death in stroke

  Excessive amounts of glutamate leading to excitotoxicity, not simply starvation of cells
• Pathology of stroke


  1. Inflammation (sodium ions, water, swelling, microglia, blood-brain barrier breakdown, oedema, cytokines)

  2. Cell death (apoptosis, necrosis, caspases, DNA breakdown, PARP)

  3. Reperfusion injury (hyperperfusion, intracranial haemorrhage/edema, damage to blood-brain barrier)
• Cerebral stroke leads to massive cell death
• Ischemic lesion = excitotoxic lesion
• Stroke causes a cascade of further complex events including inflammation, cell death, and reperfusion