Vibration and Proprioception

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Vibration

Testing Method

Firmly strike a 128 Hz tuning fork against a solid object and place the base of the fork on a bony prominence on the distal lower extremity (for lower limbs usually the first metatarsal head, or some texts say start at the toe tips). The test can be binary (felt or not felt), graded by duration, or comparative (compare with contralateral side). If it is normal distally then stop there. If it is not felt at the great toe then gradually move proximally - medial malleolus, tibial tuberosity, ASIS. For the arms start at the fingers, move up through the ICPJ, MCPJ, wrist, elbow, and shoulder.

Age (years)	Normal (seconds minimum)
≤ 20	15
21-30	14
31-40	13
41-50	12
51-60	11
> 70	Unreliable

The Rydel-Seiffer tuning fork can be used for a more quantitative assessment. This has been validated with sensory nerve action potentials and is used in outcome measures for neuropathy assessment. It has a black triange on one prong and a white triangle on the other. After striking the fork there is an illusion where each triangle becomes two, and the intersection between them gradually moves up the scale from 0 to 8 as the vibration dies down. When the patient can no longer feel the vibration the examiner notes the the intersection number on the prong at that point in time.

The white triangle should completely ignored or manually coloured in to also be black as the white can cause an unwanted optical illusion and interfere with accurate grading. Values taking from the white triangle are consistently lower. The original fork had two black triangles, and it is unknown why modern ones started having one black and one white.

Proprioception

The term proprioception is somewhat contested. In its narrowest basic neuroanatomical definition it is defined as only the senses of position and movement of one's own body parts. However in many clinical texts the definition expands to include senses from deep tissues such as vibration, deep pressure, and even deep pain, in addition to position and movement.

Testing Method

Grasp the great toe by its medial and lateral borders. While the patient closes their eyes, give the instruction "I'm going to move your toe either up or down. Tell me which way I move it." Then passively dorsiflex or plantarflex the toe approximately 45 degrees and ask if they are moving it up or down.

Do approximately 10 trials to minimise the chance of a false negative. Any incorrect responses are consistent with some degree of proprioceptive impairment. Like with vibration, if it is abnormal distally then move proximally until it is normal.

This is technically a test of kinesthesia, the sensation of movement.