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Vibration Sense

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)
     
     
    3rd Order Nuclei
    Ventral posterolateral (VPL) nucleus of thalamus
     
     
    Central Pathway
    Medial lemniscus
    Decussation
    Medulla
     
    2nd Order Nuclei
    Lower medulla - nucleus cuneatus (UL) / gracilis (LL)
     
     
    Spinal Pathway
    Dorsal column - fasciculus cuneatus (UL) / gracilis (LL)
     
    1st Order Nuclei
    Dorsal root ganglion
     
     
    Receptors
    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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