To accurately assess your patient's neurologic response, you must ensure that you've adequately stimulated him. Sometimes, calling his name, shouting, or gently shaking him is enough. However, if he doesn't respond to these methods, you'll need to apply a painful stimulus in an acceptable way.
Painful stimuli are classified as central (response via the brain) or peripheral (reflex response via the spine). Whichever type you use, a good general rule is to apply it until the patient responds, or for at least 15 seconds but no more than 30 seconds if he fails to respond. Use painful stimuli with caution if they create a significant or sustained rise in the patient's intracranial pressure.
Applying a central stimulus
Use painful central stimuli to evaluate brain function. They should get a response from the patient if he isn't comatose. His reaction to the stimulus can assist in determining his level of consciousness as well as his motor response.
Acceptable central stimuli include squeezing the trapezius muscle, applying supraorbital or mandibular pressure, and rubbing the sternum. Your patient's response may include moaning, pushing you away, trying to grab your hand, or posturing.
Applying a peripheral stimulus
Using peripheral pain to elicit a response isn't an effective test of brain function. A response may indicate that the patient feels the stimulus, but the response is from the spinal cord. If your patient didn't respond at all to central stimuli, apply a peripheral stimulus to all four extremities to establish a baseline. If all but one of his extremities responded to a central stimulus, test only the nonresponsive extremity. Pressing on his nail plate with a pencil, as shown at left, is an acceptable technique.
Hickey J. The Clinical Practice of Neurological and Neurosurgical Nursing
. 6th ed. Philadelphia, PA.: Lippincott Williams & Wilkins; 2008.