The two most common pathological reflex tests are named for the scientists who discovered them. The Hoffman sign occurs when the middle finger is bent back and flicked, and the thumb and index finger jerk instead of remaining still. The Babinski sign occurs when the sole of the foot is stroked along the side, and the big toe goes up instead of down and the other toes fan out.
In multiple sclerosis (MS), when there is weakness and spasticity in a limb, the reflexes will be increased and a pathological reflex will be present. If there is ataxia in a limb, the reflexes may be decreased. Thus, the relative presence or absence of reflexes serve as confirmatory signs to document a lesion in the spinal cord, brain stem-cerebellum, or cerebrum.
Occasionally, other miscellaneous reflexes are tested in the face, abdomen, and groin. In a normal abdominal reflex the stomach wall twitches when stroked vertically with a stick. If this reflex is diminished, it indicates an abnormal finding. This test, however, is often misleading if the patient has lost reflexes because of such other factors as obesity, abdominal surgery, childbearing, or even too cold a temperature in the examination room. The cremasteric reflex, found in males only, is a twitch response that follows the stroking of the inside of the thigh. The absence of this reflex is an abnormal finding. The palmo-mental sign is a twitching of the patient's chin when the palm is stroked. Normally there is no reaction. The jaw-jerk reflex occurs when the jaw is tapped while the mouth is open. Normally this test should produce only a slight jerk. It is abnormal when the reflex is more prominent or hyperactive. The snout reflex is tested to see if the lips pout out after the upper lip is tapped while the mouth is closed. Normally there is no response. The glabellar reflex is tested to see if the eyes continue to blink after tapping between the eyebrows. Normally the person will blink but stop when the tapping stops. (An abnormal glabellar reflex, however, is more suggestive of Parkinson's disease than MS.) The grasp reflex is tested to check for an involuntary grasp response that occurs when the palm is stroked. Normally the hand remains still. These miscellaneous reflex tests are done on occasion, but the more conventional reflex tests are more valuable and leave less room for subjective observation.