Examination of Vibration and Position Sensation

By admin On Dec 12, 2024

Ovid: Field Guide to the Neurologic Examination

Authors: Lewis, Steven L.

Title: Field Guide to the Neurologic Examination, 1st Edition

> Table of Contents > Section 2
– Neurologic Examination > Sensory Examination > Chapter 30 –
Examination of Vibration and Position Sensation

Chapter 30

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

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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.
The same procedure can be performed, if
necessary, in the upper extremities, starting in the distal finger
joints. Vibratory sensation testing in the upper extremities should be
performed particularly when significant vibration sense loss is found
in the lower extremities.

Position Sense (Proprioception)

Inform the patient that you will be
moving his or her big toe up (“toward the ceiling”) or down (“toward
the ground”) and that you will be asking him or her to tell you in
which direction you have just moved it. If the patient is lying in bed,
“up” and “down” might not be so obvious, so it is helpful to clarify
that “toward your head is up” and “toward me is down” if you are
standing at the foot of the bed.
Ask the patient to close his or her eyes.
Start your examination by testing the
toes. Hold the distal phalanx of the patient’s large toe on the sides,
with your thumb on one side and your index finger on the other side.
Don’t hold one finger on the top and the other on the bottom, because
your pressure would then give the patient a clue to the direction the
toe is moving.
While moving the patient’s toe slightly upward or downward, ask the patient, “Am I moving your toe up or down?”

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Repeat the same process a few times with
the same toe until you are convinced that the patient consistently
gives the correct response or is making errors.
Perform the same test on the large toe of the patient’s other foot.
If the patient’s responses are incorrect
distally, proprioception should be checked more and more proximally by
checking the patient’s ability to detect up and down movements of the
proximal phalanx or the ankle or even the knee.
The same procedure can be performed, if
necessary, in the upper extremities, starting in the distal finger
joints. Position testing in the upper extremities should be performed
particularly when significant position sense loss is found in the lower
extremities.

NORMAL FINDINGS

Vibration Sense

Normally, patients should be able to feel the vibration
from a slightly vibrating tuning fork in the distal toes and fingers.
Use your perception of the vibrating tuning fork as you hold it on the
patient to help guide what you think the neurologically healthy patient
should be able to feel. The ability to detect vibration in the distal
lower extremities does diminish with age, however, so neurologically
healthy elderly patients may be expected to have at least a mild loss
of vibration sensation in the toes, as compared to younger patients,
even in the absence of sensory complaints or any clinically relevant
nerve or spinal cord dysfunction.

Position Sense (Proprioception)

Normally, patients should be able to correctly detect
the direction of small upward and downward movements in the toes and
fingers. Proprioceptive sensation as tested clinically does not seem to
significantly diminish with age.

ABNORMAL FINDINGS

Vibration Sense

The inability to feel the vibration from
a slightly vibrating tuning fork in the toes is abnormal in nonelderly
patients, and the inability to feel a moderately vibrating tuning fork
is abnormal in elderly patients. Report the patient’s vibratory loss as
mild, moderate, or severe. This can be described in several ways
depending on the severity of the finding, such as “There is mild
vibratory loss in the toes” or “There is severe vibratory loss up to
the knees.” Generally, the more severe the vibratory loss, the more
likely the finding is to be clinically significant.
Abnormal vibratory sensation in the lower
extremities mainly suggests the presence of a peripheral neuropathy
(sensory polyneuropathy), dysfunction of multiple lumbar nerve roots
(lumbosacral polyradiculopathy), or a process within the spinal cord
(myelopathy) at any level affecting the posterior columns. As with any
examination finding, you would need to synthesize the findings from the
history and the rest of the examination to try to distinguish between
these possibilities.
Vibratory loss in the upper extremities and the lower extremities suggests a severe polyneuropathy or a cervical myelopathy.

Position Sense

The inability to correctly detect the
direction of small upward or downward movements of the toes is abnormal
and consistent with proprioceptive

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dysfunction;
this is seen mainly in the clinical setting of a severe peripheral
polyneuropathy or from spinal cord dysfunction (myelopathy) at any
level affecting the posterior columns.
Position sense loss in both the upper and
the lower extremities suggests a severe sensory polyneuropathy or a
cervical myelopathy.

ADDITIONAL POINTS

The method of vibratory sense testing
described here is different than the way many physicians perform the
test. Many clinicians are taught to hold the vibrating tuning fork to
the toe and ask the patient to let them know when the vibration has
died down—this method takes too much time and runs the risk of the
patient and physician becoming habituated to the sensory stimulus and
bored.
Assessing vibration sense routinely
provides a better idea of the normal range of ability to detect
vibration sense in the toes and the normal mild reduction in this
ability with age. In addition, grading vibratory loss from mild to
moderate to severe is subjective and is aided by testing lots of
patients.
Testing for position sense is not a
substitute for testing vibration sense, because vibratory loss is a
more sensitive and early symptom of sensory nerve or posterior column
dysfunction than is position sense.
Severe loss of vibration and position
sense can also be seen as a result of dysfunction of the dorsal root
ganglion cells (sensory neuronopathies); in these patients, loss of
proprioception is often quite severe and can lead to the upper
extremities assuming abnormal postures when the eyes are closed (called
pseudoathetosis).
Vibration and position sense can
theoretically be affected by lesions above the cord, such as the
thalamus or the parietal cortex. In practice, however, these tests are
most helpful in diagnosing spinal cord or peripheral nerve dysfunction.
When testing vibration and position sense, it’s best to concentrate
more on detecting the proximal-distal extent of loss than side-to-side
differences.
Asymmetric loss of posterior column
sensation should be sought, however, when a hemi-spinal cord process is
suspected (Brown-Séquard syndrome). In this syndrome, diminished
posterior column sensation would be expected on the same side as
weakness but contralateral to the side of pinprick sensation loss (see Chapter 51, Examination of the Patient with a Suspected Spinal Cord Problem).