Examination of Vibration and Position Sensation
PURPOSE
The main purpose of the examination of vibration and position (proprioception) sense is to assess for evidence of dysfunction of the peripheral sensory nerves in the extremities or the sensory pathways in the spinal cord.
WHEN TO EXAMINE VIBRATION AND POSITION SENSATION
Testing of vibratory sensation should be performed in all patients as part of a routine neurologic examination. Testing of vibration sense is particularly important in patients with sensory symptoms, such as numbness or tingling, or in any patient being assessed for the possibility of a peripheral nerve or spinal cord process.
Testing for position sense probably does not need to be performed routinely; however, position sense should be tested in all patients who have sensory symptoms, in patients who have significant sensory findings to vibration or pin, or in patients with a complaint of problems with gait or balance.
NEUROANATOMY OF VIBRATION AND POSITION SENSE
The pathways for vibration and joint position sense begin in peripheral sensory receptors. Information from these receptors travels up the peripheral nerves to the dorsal roots to enter the spinal cord, ascends the ipsilateral spinal cord as the posterior columns, crosses to the contralateral side in the low medulla, and then ascends through the brainstem to reach the thalamus and the parietal cortex. In other words, vibration and proprioceptive sensation felt on the left side ascends the left posterior spinal cord and crosses in the medulla to end up in the right thalamus and right sensory cortex.
EQUIPMENT NEEDED TO TEST VIBRATION AND POSITION SENSE
128-Hz tuning fork.
HOW TO EXAMINE VIBRATION AND POSITION SENSE
Vibration Sense
Inform the patient that you will be using a vibrating (“buzzing”) tuning fork to determine how well he or she feels this sensation.
It is helpful to start by making sure that the patient understands the definition of the sensation of the vibrating tuning fork as compared to the sensation of the nonvibrating tuning fork. To do this, have the patient keep his or her eyes open and strike the tuning fork (on your other hand) so that a moderate degree of vibration occurs. While holding the stem of the tuning fork between your thumb and index
finger, place the base of the tuning fork on an area where you would expect most patients to be able to feel it, such as on the wrist or forehead. Say to the patient, “This is vibration” (or “buzzing”), and, then, keeping the tuning fork on the patient, stop it from vibrating and say, “This is no vibration” (or “no buzzing”). Once you are convinced that the patient understands the ground rules of the test, proceed to testing vibratory sense.
Ask the patient to close his or her eyes.
Strike the tuning fork so that a slight degree of vibration occurs and, while holding the stem of the tuning fork between your thumb and index finger, place the base of the tuning fork on the distal phalanx of the patient’s large toe and ask if he or she feels vibration (or “buzzing”) or no vibration (or “no buzzing”).
If the patient states that he or she can feel the slightly vibrating tuning fork, confirm that the patient actually felt the vibration by performing the same test but, this time, stop the tuning fork from vibrating before placing it on the patient’s large toe. Again ask the patient if he or she feels vibration or no vibration. If the patient appropriately describes this as “no vibration,” then the patient’s (normal) ability to feel the slightly vibrating tuning fork in that extremity (step 4) has been confirmed, and there is no need to proceed with further testing in that extremity.
Perform the same test as step 4 on the large toe of the patient’s other foot.
If the patient is not able to feel the slightly vibrating tuning fork distally, repeat the process with higher amplitude vibrations (by striking the tuning fork more strongly) and see how strong the vibration needs to be before the patient can feel the tuning fork distally. Each time you hold the tuning fork to the patient, ask if he or she feels vibration (or “buzzing”) or no vibration (or “no buzzing”). In addition, you can assess for the severity of the proximal extent of the vibratory loss by striking the tuning fork to a moderate level of vibration, then placing it over more proximal bony prominences (the dorsum of the foot, the medial or lateral malleolus, the anterior shin, the knee, or even the iliac crest) until the patient states that he or she can feel the vibration.Related posts:
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