Pain Sensation | Signs - MedSchool
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Pain Sensation

Overview

  • Pain sensation is conveyed via the spinothalamic pathway, and mapping of this can be used to determine the distribution of a patient's sensory loss.
    • How to Assess

    • Demonstrate a sharp stimulus by touching the patient lightly on the chest with a neurotip. Ask the patient to close their eyes, and test each dermatome / nerve distribution alternating between the sharp and dull sides of the neurotip at random. Ask the patient if they percieve the stimulus as sharp or dull.
    • Causes of Isolated Pain and Temperature Sensory Loss

    • Anterior spinal artery occlusion
    • Dorsolateral medulla / pons lesion

The Spinothalamic Pathway

  • Cortical Centre
    Primary sensory cortex (postcentral gyrus)
     
     
    3rd Order Nuclei
    Ventral posterolateral (VPL) nucleus of thalamus
     
     
    Spinal Pathway
    Lateral spinothalamic tract
    Decussation
    Level of entry into spinal cord
     
    2nd Order Nuclei
    Dorsal horn at level of entry into spinal cord
     
     
    1st Order Nuclei
    Dorsal root ganglion
     
     
    Receptors
    Free nerve endings
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