Week 24: Brain Dysfunction

• Brain Dysfunction


  • Functional, such as Autism, Obsessive compulsive disorder (OCD), Major depression
  • Structural, such as Stroke, Dementia, Traumatic brain injury
• Stroke


  • Ischemic: Thrombotic (blood clot formed within the blood vessel), Embolic (clot formed outside the blood vessel)
  • Haemorrhagic: bleed from artery into the brain
• Ischemic Stroke


  1. Middle Cerebral Artery (MCA): motor, sensory and language functions

  2. Posterior Cerebral Artery (PCA): vision and memory

  3. Anterior Cerebral Artery (ACA): executive functions and partly sensory and motor function
• Dementia


  An acquired persistent impairment of intellectual function with compromise in memory and at least two other cognitive domains such as language, visuospatial skills, social, occupational, or executive function.
• Types of Dementia


  • Neurodegenerative disorders: Alzheimer's disease, Frontotemporal Dementia / Pick's Disease
  • Non-degenerative: Vascular (multi-infarct) dementia, Toxins, Infection, Alcohol
• Parkinson's disease


  • Hypokinetic: characterised by a partial or complete loss of muscle movement due to a disruption in the basal ganglia
  • experience muscle rigidity and an inability to produce movement
• Huntington's disease


  • Hyperkinetic: characterised by frenetic energy or activity; hyperactive
• Basal Ganglia


  The main components of the basal ganglia – as defined functionally – are the striatum (also called corpus striatum and striate nucleus), consisting of both the dorsal striatum (caudate nucleus and putamen) and the ventral striatum (nucleus accumbens and olfactory tubercle), the globus pallidus, the ventral pallidum, the substantia nigra, and the subthalamic nucleus.
• Ischemic Stroke


  Loss of blood flow via vessel blockage
• Types of Ischemic Stroke


  • Thrombotic (~60%)
  • Embolic (~20%)
• Thrombotic Ischemic Stroke


  • Blood clot formed within the blood vessel
  • Can often build up around atherosclerosis
• Embolic Ischemic Stroke


  • Clot formed outside the blood vessel and travels to brain and becomes lodged
  • Could be cholesterol build-ups (atherosclerosis) coming from neck blood vessels and travel to brain
• Haemorrhagic Stroke


  • Bleed from artery into the brain
  • Blood builds up inside skull and compresses brain tissue
  • Some loss of blood flow can be possible too
• Ischemic Stroke Locations


  • Middle Cerebral Artery (MCA)
  • Posterior Cerebral Artery (PCA)
  • Anterior Cerebral Artery (ACA)
• Chronic Ischemic Stroke - Anterior Cerebral Artery (ACA)


  • Can affect some medial parts of the pre/post central gyrus
  • Sensory/motor loss
  • Executive dysfunction
• Chronic Ischemic Stroke - Middle Cerebral Artery (MCA)


  • Tend to affect pre-central (motor) and post-central gyrus (sensory) on one side
  • Leads to hemi-paralysis and loss of sensation on one side
  • Can affect language
• Chronic Ischemic Stroke - Posterior Cerebral Artery (PCA)


  • May affect vision...blindness
  • Object recognition problems
  • Memory problems
• Ischemic Stroke Treatment - Acute


  1. Special clot busting drugs

  2. Must be sure that it is not a Hemorrhage

  3. Must be done early (within 3-4 hours)

  4. Early intervention may reduce extent of stroke
• Ischemic Stroke Treatment - Chronic


  1. Therapy for physical disabilities

  2. Therapy for language/cognitive difficulties

  3. Adaptation to body/cognitive limitations

  4. Some natural recovery, especially in young people
• Haemorrhagic Stroke


  • Build up of pressure within skull...brain compression
  • Brain soft, high blood pressure can squish
  • Interferes with normal cell function due to abnormal flow of blood
• Alzheimer's Disease


  • Cognitive deficits
  • Profound memory loss (anterograde/retrograde)
  • Language - anomic, empty, circumlocutory
  • Visuospatial disturbance
  • Behavioural deficits
  • No significant early changes in personality
  • Unawareness or denial of illness
  • Psychosis
  • No primary sensory or motor loss
• Retrograde Amnesia


  Inability to remember past
• Anterograde Amnesia


  Inability to form new memories
• Anomic aphasia


  Language disorder that leads to trouble naming objects
• Circumlocutory language disorder


  Where the patient refers to an object, event or person, describing its characteristics instead of using its name
• Empty language impairment


  Phonological disorder that affects the phonological (phonemic) level. The patient has difficulty organising their speech sounds into a system of sound contrasts (phonemic contrasts).
• Normal Blood Flow


  Alzheimer's: Lost - posterior/parietal areas, Reserved - frontal lobes
• Alzheimer's Disease - Pathology


  • Dendritic Arbour Reduction
  • Less connections with other neurons
• Frontotemporal Dementia / Pick's Disease


  • Cognitive deficits
  • Profound executive dysfunction (Frontal damage)
  • Memory and language impairment (Temporal damage)
  • Behavioural deficits
  • Early prominent personality changes
  • Poor judgment, insight, disinhibited, labile, euphoric, socially inappropriate, sexual indiscretions
  • No sensory or motor deficits
• Parkinson's Disease


  • Onset 40-70 years old (older population)
  • Progresses over 10-20 years
  • Around 0.3% population (200K in UK)
  • Resting Tremor
  • Bradykinesia (slow movement)
• Parkinson's Disease - Role of Dopamine


  Decrease dopamine in basal ganglia
• Huntington's Disease


  • Hyperkinetic
  • Typical onset around 40 years old
  • Progresses over 10-15 years
  • Much less common than Parkinson's disease
  • Genetically transmitted
  • If you have it, your children have 50% chance
• Huntington's Disease Symptoms


  • Behavioral changes - depression, mood swings
  • Abnormal movements - Chorea (involuntary movements of the face, neck and limbs), Athetosis (slow, writhing movements confined to the limbs)
  • Dementia (global cognitive impairments)
• Parkinson's Disease - Resting Tremor

  Tremor of one hand is a common early sign

  Often improves or disappears with purposeful function