neurologic disorders
How to Assess Reflexes
Pathologic reflexes
Pathologic reflexes (eg, Babinski, Chaddock, Oppenheim, snout, rooting, grasp) are reversions to primitive responses and indicate loss of cortical inhibition. Babinski, Chaddock, and Oppenheim reflexesall evaluate the plantar response. The normal reflex response is flexion of the great toe. An abnormal response is slower and consists of extension of the great toe with fanning of the other toes and often knee and hip flexion. This reaction is of spinal reflex origin and indicates spinal disinhibition due to an upper motor neuron lesion. For Babinski reflex, the lateral sole of the foot is firmly stroked from the heel to the ball of the foot with a tongue blade or end of a reflex hammer. The stimulus must be noxious but not injurious; stroking should not veer too medially, or it may inadvertently induce a primitive grasp reflex. In sensitive patients, the reflex response may be masked by quick voluntary withdrawal of the foot, which is not a problem in Chaddock or Oppenheim reflex testing. For Chaddock reflex, the lateral foot, from lateral malleolus to small toe, is stroked with a blunt instrument. For the Oppenheim reflex, the anterior tibia, from just below the patella to the foot, is firmly stroked with a knuckle. The Oppenheim test may be used with the Babinski test or the Chaddock test to make withdrawal less likely. Thesnout reflexis present if tapping a tongue blade across the lips causes pursing of the lips. Therooting reflexis present if stroking the lateral upper lip causes movement of the mouth toward the stimulus. Thegrasp reflexis present if gently stroking the palm of the patient’s hand causes the fingers to flex and grasp the examiner’s finger. Thepalmomental reflexis present if stroking the palm of the hand causes contraction of the ipsilateral mentalis muscle of the lower lip. Hoffmann signis present if flicking down on the nail on the 3rd or 4th finger elicits involuntary flexion of the distal phalanx of the thumb and index finger. Tromner signis similar to the Hoffman sign, but the finger is flicked upward. For theglabellar sign, the forehead is tapped to induce blinking; normally, each of the first 5 taps induces a single blink, then the reflex fatigues. Blinking persists in patients with diffuse cerebral dysfunction. 