Interactive Guide to Physical Examination
The sensory exam involves evaluation of pain (or temperature), light touch, position sense, vibration, and discriminative sensations. This portion of the exam is very subjective, and may become unreliable if repeated in quick succession. Therefore, your exam should not be rushed, but must proceed efficiently. Compare symmetrical areas on both sides of the body and compare proximal to distal areas.
Test pain using a sharp object. Objects frequently used include the point of a safety pin or a wooden tongue depressor broken to create a sharp edge. Take care not to puncture the skin, and remember that universal precautions require you to discard the instrument after examination. Using the sharp point, apply light pressure to the skin. At minimum, test the shoulders, arms and legs, comparing side to side and proximal to distal areas. In any area where the patient complains of sensory loss or hypersensitivity, more detailed testing may be required.
Using your fingertips or a wisp of cotton, lightly stroke the skin and determine if the patient feels this symmetrically in all areas tested. Again, test the areas outlined above.
Usually, if pain sensation has been tested and is normal, there is no need to test temperature sensation. To test cold sensation, apply the cool tines of your tuning fork to the skin in the areas outlined above. To test warm sensation, use a glass tube or other container filled with warm water.
With the patient's eyes closed, test his ability to determine the direction of movement as you move the great toe upward or downward. When moving a digit, it is important to grasp it on both sides, rather than on the top and bottom. This is because pressure sensation on the top or bottom of the digit will help the patient determine position sense, even if proprioception is impaired. Repeat several times on each side, and in upper extremities using the thumb. Test a more proximal joint (for example ankle or wrist) if an abnormal response is obtained.
Test vibratory sense on each side, using a 128 Hz or 256 Hz tuning fork, by placing the vibrating fork on the boney prominence of a finger or toe. Ask the patient to tell you what he feels. He should report this sensation as a vibration. Then ask him to tell you when he no longer feels the vibration. If there is impaired vibratory sense, test a more proximal bony prominence. With aging, vibratory sense may be diminished or lost in the feet and ankles.
A disproportionate loss of vibratory sense and proprioception (compared to pain sensation) tends to suggest disease of the dorsal columns (e.g. tabes dorsalis, Vitamin B12 deficiency, multiple sclerosis) or demyelinating neuropathies.
The sensory cortex is involved in correlating, analyzing, and interpreting sensations. Three tests used to evaluate these abilities are: two-point discrimination, stereognosis and graphesthesia. These tests are dependent on the patient having a normal sense of touch, or only minimally impaired. The patient's eyes should be closed for each of these tests.
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Click on the video icon to view a demonstration of the sensory exam. |
