Subcortical Disorders

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Subcortical Disorders

• Thomas G. Bowers, Ph.D.

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Karen Quinland Case
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Pathology Sample
Kinney, Korein, Panigraphy et al. (1994)
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Karen Quinland

• Pathology sample indicated prominent subcortical
  damage
• Especially in the thalamus
• However, there is also evidence of considerable
  cortical damage
• 835 grams

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Anthony Bland Case

• At age 18 suffered cerebral anoxia secondary to
  crushing injuries.
• Brain weighed 1007 grams (average 1300 grams).
• Narrowed gyri, cerebral atrophy

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AB Pathology Sample
Jarmulowicz (1995), Catholic Medical Quarterly
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AB Pathology Sample
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Cingulate Gyrus
Mamimilary Bodies
Fornix
Anterior Thalamus
Hypothalamus
Hippocampus
The Circuit of Papez An Early Model of Neural
Substrates of Emotion
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White Matter in Cognition

• Three types of white matter fibers
• 1. Association fibers
• Connect different regions
• 2. Commissural fibers
• Connect corresponding hemispheres
• 3. Projection fibers
• Up-down

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White Matter Changes in Aging

• Leukoaraisosis
• No mass effect, does not enhance
• Periventricular sources
• Glio cell loss
• Small vessel infarct
• Arteriosclerosis
• Infection/inflammation
• Demyelination
• Vasculitides

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MRI Characteristics

• Patchy, diffuse hyperdensity
• Pencil thin lines

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Cognitive Characteristics

• Attentional processes
• Working memory (not span)
• Encoding and retrieval
• Spatial rotation
• Discourse comprehension

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Disease Processes

• 1. Infection and autoimmune disorders
• 2. Vasculitis
• 3. Multiple sclerosis (MS)
• 4. HIV
• 5. Neurotoxic
• 6. Gliomas

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Infection and Autoimmune

• Systemic lupus
• 1. cognitive impairment fluctuates
• 2. Can appear manic
• 3. Deficits in retrieval, delayed recall
• 4. Problems in cognitive speed and flexibility
• Vasculitis
• Inflammation of blood vessels

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Multiple Sclerosis (MS)

• Variable lesions in white matter and corpus
  callosum
• Many different clinical courses
• Periventricular changes
• Very impaired on divided attention tasks

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Multiple Sclerosis (MS)

• Problems in reading comprehension, visual memory
  retrieval, verbal memory, motor slowing
• Executive dysfunction
• Negative recency effect noted
• Possible loss of temporal codes
• Do well on STM tasks

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HIV

• Patchy white matter changes
• Atrophy in later stages
• Prodromal stage (up to 2 years)
• May be only mildly symptomatic
• Attention deficits
• Memory deficits
• Slowed processing
• Impaired conceptual processing
• Impaired self monitoring

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Neurotoxic Injury

• Solvents
• Acute and late developing effects
• Headaches, dizziness, mild depression, impaired
  behavioral control
• Problems in attention, self-monitoring
• Chronic CO exposure

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Gliomas

• Astrocytomas (glioblastoma multiforme)

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Ischemic Vascular Dementia

• Leukencephalopathy
• 1. Arteriosclerosis
• 2. Spasm
• 3. Transitant ischemia
• Severity related to brain tissue loss
• 1. decreased processing efficiency
• 2. retrieval failures
• 3. problems with semantic access
• 4. spatial rotation impairment
• 5. selective executive dysfunction

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Progressive gliosis

• Also progressive subcortical gliosis
• Often may cause frontal problems

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Frontal Lobe Dementia

• Changes in eating habits
• Sleep disturbance
• Somatic complaints
• Mute, empty behaviors
• Not amnesic, but fail to use memory

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Diffuse Axonal Injury

• Acceleration/deceleration rotational forces
• Yields shearing
• Mechanical forces lead to neuronal segmentation,
  small hemorrhages, edema

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Diffuse Axonal Injury

• Povlishock work
• Shearing due to axonal swelling, not mechanical
  tearing
• Wallerian degeneration ensues
• Evolves in 6-24 hours
• Affects more distal axons
• No disruption of myelin, of cell
• retraction ball forms

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Radiation Injury to Brain

• Acute effects
• Edema, elevated ICP
• Early delayed effects, inhibition f myelin
  synthesis
• Late delayed effects, damage to myelin, vascular
  damage, immune processes
• Nausea, headache, drowsiness, anorexia
• Verbal semantic LTM retrieval problems
• Memory/motor dysfunction

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Radiation Injury to Brain

• Dementia can occur and lead to death
• More likely memory decline, gradual recovery

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Summary

• White matter difficulty yields problems in
  complex cognitive processing
• Problems in processing speed
• Difficulties with high cognitive demands
• Problems with complex stimulus demands, as
  rotations
• Problems with attentional monitoring
• Impairment with multiple associations

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Summary

• Object recognition is unimpaired, knowledge in
  unimpaired
• No single modality of input is impaired, but
  multiple input is impaired