Pain Sensation
August 19th, 2017
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)
Primary sensory cortex (postcentral gyrus)
3rd Order Nuclei
Ventral posterolateral (VPL) nucleus of thalamus
Ventral posterolateral (VPL) nucleus of thalamus
Spinal Pathway
Lateral spinothalamic tract
Lateral spinothalamic tract
Decussation
Level of entry into spinal cord
Level of entry into spinal cord
2nd Order Nuclei
Dorsal horn at level of entry into spinal cord
Dorsal horn at level of entry into spinal cord
1st Order Nuclei
Dorsal root ganglion
Dorsal root ganglion
Receptors
Free nerve endings
Free nerve endings
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------