Sensory Exam

In a screening sensory examination, light touch, pain, and vibration are tested in the feet. The sensory examination is expanded in a patient with a complaint referable to the nervous system, or if other components of the examination are abnormal.

1. Primary sensory testing

Begin primary sensory testing by asking the patient if there is any change in sensation in the body. The patient can describe and demarcate the sensory changes to aid in the evaluation.

1. Light touch
   1. Using the tip of your finger or a piece of cotton, touch rather than stroke the patient's skin. Ask the patient to close eyes and tell you when the touch is felt.
2. Pain
   1. Explain that you will be touching the patient with either the sharp or dull end of a safety pin, but it should not hurt.
   2. With the patient's eyes closed, touch the hand, thumb and fingers with the sharp end of the pin but include a dull stimulus as well. With each touch, ask the patient to determine if the stimulus is "dull" or "sharp." Then move up the arm using the same technique.
   3. Repeat on the other hand and arm, and compare between the sides.
   4. Repeat pinprick on the anterior side of the chest wall and compare the sides.
   5. Test the pain sensation in the lower extremities, beginning distally in the feet and comparing between symmetric areas on the two sides of the body and between the distal and the proximal areas.
   6. If an area of numbness is found on the patient, begin testing at the numb area and work outward. Instruct the patient to say "yes" when feeling the normal pinprick sensation. Try to assess if there is a dermatomal pattern of sensory loss, which may be seen with a peripheral nerve injury.
3. Temperature
   Use the tuning fork as a cold stimulus to test temperature sensation. Test tubes containing warm and cold water could be used as stimuli, but this is not usually done. Temperature sensation should replicate the findings found on the pain sensation examination. Typically only one or the other is performed.
   1. Test the temperature sensation by touching the patient's skin with the tuning fork over the extremities in the same way the pain sensation is tested.
   2. Compare between the sides and between the proximal and distal areas of the same extremity.
4. Vibration
   1. Use a low-pitched tuning fork of 128 Hz and strike the tines against the heel of your hand to produce a vibration.
   2. Place the stem of the tuning fork on the patient's great toe,
   3. Ask the patient to tell you when the vibration is no longer felt. Let the vibration fade until the patient no longer detects it, then apply the tuning fork to your own thumb to see if you still feel any vibration. To make the vibration decrease faster, run your finger along the tines to dampen the vibration.
   4. If the patient cannot feel the vibration in the toes at all, repeat the test by placing the fork over the medial malleolus and, if not felt there, move the fork over the patella.
   5. Record the most distal level where the stimulus is felt.
   6. Compare the two sides.
   7. If there was decreased vibration appreciation found on examination of the lower extremities, test if the vibration can be appreciated in the fingers.
5. Proprioception
   1. Hold the patient's large toe on the sides and demonstrate the test by moving the toe upward and downward while saying, "This is moving it up, and this is moving it down."
   2. Then instruct the patient to close the eyes and to correctly identify the direction as you move the toe up and down in a random order.
   3. Repeat the same on the other side. If the patient cannot correctly identify movements of even large excursions, attempt to move the foot up and down around the ankle joint.
   4. Normally, people are able to identify even a few degrees of movement. If any indication of abnormality is present, test the position sense in the fingers at the metacarpophalangeal joints.

2. Cortical sensation

1. Tactile localization (double simultaneous stimulation; extinction).
   1. With the patient's eyes closed, ask the patient to localize where you have touched. Initially, touch the side that you are concerned may have a deficit to confirm that sensation to light touch is intact. Then, simultaneously touch both sides and ask the patient to identify where and how many places were touched.
   2. Touch the patient on one arm and then simultaneously on both arms. Do the same with the legs.
   3. Extinction of the stimulus on one side may be a sign of a lesion in the contralateral parietal cortex.
   4. If there are suspected lesions of the sensory cortex, additional testing may be performed, including two-point discrimination, point localization, and looking for any asymmetry of optokinetic nystagmus.
2. Stereognosis tests the patient's ability to identify a common object (e.g., nickel, dime, quarter, penny, key, paper clip) placed in the hand.
   1. Ask the patient to close the eyes and then identify the small object in the hand. The patient may move the object around in the hand to feel it.
   2. Test the other hand in the same way. Importantly, the patient may not transfer the object from hand to hand. The patient should be able to identify it with one hand at a time. Patients should be able to differentiate coins, so it is not an acceptable answer to say "coin." The patient should be able to correctly determine a "nickel" or "quarter."
3. Graphesthesia tests the ability to identify numbers or letters drawn on the patient's hand.
   1. Ask the patient to close the eyes. Use the blunt end of a pen to draw a large rendition of a number from 0-9 on the patient's palm. Make sure that the number is facing the patient and not you.
   2. Ask the patient to identify the number. Allow several trials.
   3. Test the hand that you think is not affected first. Then, repeat on the other side. Inability to correctly identify numbers may be indicative of a lesion in the contralateral parietal cortex.