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How to Perform a Dermatome Evaluation

Dermatome testing is part of a neurological examination. A dermatome is a patch of skin that is supplied by one particular nerve coming from the spinal cord. The nerves from the upper cervical spine supply the skin of the neck and so on down the body (dermatome maps are available on the Internet). Testing a dermatome means stimulating an area of skin in various ways to see how the nerve that supplies it is functioning. Absence or distortion of any response can indicate nerve damage.

Things You'll Need

  • disposable sharp object (broken tongue depressor)
  • disposable dull object (cotton swab)
  • 128 Hz tuning fork
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Instructions

  1. Test for Pain

    • 1

      Ask the patient to close his eyes.

    • 2

      Tell the patient that you are going to touch him with both a sharp object and a dull one, and ask him to tell you which object you are using. Demonstrate both touches to assure him that the test will not actually hurt.

    • 3

      Touch with each object on various parts of the foot and up the leg, asking the patient to say "sharp" or "dull."

    • 4

      Note any areas where sensation is diminished or absent.

    Test Proprioception

    • 5

      Proprioception is a sense of where your body parts are in relation to each other and on motion. Test this by grasping the patient's big toe and moving it up and then down once, telling the patient which direction is which.

    • 6

      Have the patient close his eyes.

    • 7

      Now move the toe several times without saying which direction and ask the patient to tell you how you are moving the toe, "up" or "down."

    • 8

      Note the spots touched and the patient's answers.

    Test for Vibration

    • 9

      Show the patient the tuning fork and explain what you are going to do. Demonstrate its vibration by tapping the tines against the heel of your hand and letting the patient touch the handle.

    • 10

      Support the patient's foot with the fingers of one hand. Make sure your fingers are under the big toe.

    • 11

      Have the patient close his eyes.

    • 12

      Start the tuning fork vibrating and place the end of the handle on the joint where the big toe joins the foot. You should be able to feel the vibration in your hand under the patient's toe

    • 13

      Ask the patient to tell you when he can no longer feel the vibration. You should stop feeling it about the same time. Note any variance.

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