Overview
Also known as pallesthesia
How to Assess
- With the patient's eyes closed, place a vibrating 128hz tuning fork over the interphalangeal joint of the great toe. Ask the patient to describe the sensation. If they can feel it vibrating, progressively diminish the vibration until they cannot feel it. If they cannot feel it vibrating, test on the medial / lateral malleolus and then the tibial tuberosity.
This test is best performed on skin overlying bone rather than soft tissue.
Causes of Isolated Vibration and Proprioceptive Loss
- Demyelination - proprioceptive and vibration fibres are myelinated while pain sensation fibres are not.
- Brainstem lesions involving the medial lemniscus
- Dorsal spinal artery occlusion (unilateral impairment)
Dorsal Column 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
Central Pathway
Medial lemniscus
Medial lemniscus
Decussation
Medulla
Medulla
2nd Order Nuclei
Lower medulla - nucleus cuneatus (UL) / gracilis (LL)
Lower medulla - nucleus cuneatus (UL) / gracilis (LL)
Spinal Pathway
Dorsal column - fasciculus cuneatus (UL) / gracilis (LL)
Dorsal column - fasciculus cuneatus (UL) / gracilis (LL)
1st Order Nuclei
Dorsal root ganglion
Dorsal root ganglion
Receptors
Pacinian corpuscles / Merkel disc receptors / Meisner's corpuscles (vibration)
Neuromuscular spindles (proprioception)
Pacinian corpuscles / Merkel disc receptors / Meisner's corpuscles (vibration)
Neuromuscular spindles (proprioception)
Overview
Note
Vibration sense is mediated by- Merkel disc receptors (low frequencies 5-15 Hz)
- Meissner's corpuscles (mid frequencies 20-50 Hz)
- Pacinian corpuscles (high frequencies 60-400 Hz)
Therefore clinical testing of vibration is mediated by pacinian corpuscles.
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