Cortical Sensation and Higher Cortical Functioning Assessment

Introduction to Cortical Sensation

  • Cortical sensation is vital for the integration of sensory information received from the spinal cord by the parietal lobes.
  • It differs from peripheral sensory systems that assess proprioception and vibration.

Tests for Cortical Sensation

1. Stereognosis
  • Involves the ability to identify objects through touch, without visual input.
  • Procedure:
    • Patient closes their eyes and extends a hand.
    • The clinician places an object in the patient’s hand (e.g., a key).
    • The patient identifies the object by feel.
  • Example outcomes:
    • House key: correctly identified as a key.
    • Quarter: recognized correctly as a quarter.
  • Significance: Indicates proper parietal lobe function in processing tactile information.
2. Graphesthesia
  • This test assesses the ability to recognize letters or numbers drawn on the skin.
  • Procedure:
    • Patient closes their eyes.
    • The clinician draws a letter or number on the patient's palm.
    • Patient identifies what was drawn.
  • Example outcomes:
    • The number '3' recognized correctly.
    • A plus sign drawn and identified correctly.
  • Significance: Tests the cortical processing ability of the parietal lobe.
3. Extinction
  • This test evaluates the ability to perceive stimuli on both sides of the body when presented simultaneously.
  • Procedure:
    • Clinician touches both sides of the patient's body (e.g., arms) at the same time.
  • Expected responses:
    • Patient acknowledges feeling sensations on both sides with eyes closed.
  • Significance: If a patient shows sensory extinction (only feels on the dominant side), it indicates potential parietal lobe dysfunction related to a stroke or other issues.

Higher Cortical Functioning

  • After assessing cortical sensation, evaluation moves on to higher cortical functions and testing for conditions such as dementia and delirium.
Dementia Testing
  • Instruments for dementia assessment:
    • Folstein's Mini Mental Status Exam
    • Mini-Cog
    • Montreal Cognitive Assessment
    • Clock Drawing Test
  • Importance:
    • These tests are standardized, validated, and available in multiple languages.
    • They assist in diagnosing early or advanced stages of dementia and track progression.
Delirium Testing
  • The Confusion Assessment Method (CAM) is commonly used for delirium assessment.
  • Four core components (patient must meet at least 3):
    1. Acute Change and Fluctuating Course: Patient exhibits sudden changes in mental status; not gradual.
    2. Inattention: Difficulty focusing or maintaining attention, evidenced by inability to perform complex tasks.
    3. Disorganized Thinking: Incoherent speech or inability to follow a logical thought process.
    4. Altered Level of Consciousness: Trouble staying awake or requires external prompts to wake up.
  • Significance: Understanding these components is crucial for accurate delirium diagnosis, differentiating it from other progressive cognitive disorders.