Testing of the tendon reflexes at the biceps, triceps, supinator-brachioradialis, patellar, and Achilles tendon are an adequate sampling of reflex activity. Underactive or barely elicitable reflexes can be facilitated by voluntary contraction of other muscles, such as pulling the grasped hands against each other (Jendrassik maneuver).
The plantar reflexes, particularly the elicitation of the Babinski sign by stroking the lateral sole of the foot from heel to toe, are an essential part of most examinations. The sign is a dependable marker of damage to the corticospinal system as described in Chap. 3. The main features of the Babinski sign are dorsiflexion of the large toe and fanning of the other toes. Interpretation of the plantar response poses some difficulty because reactions besides the Babinski sign can be evoked. These include a quick withdrawal response of the foot and leg that does not signify disease; and a pathologic slower, spinal flexor reflex (flexion of knee and hip and dorsiflexion of toes and foot, “triple flexion”) that has similar significance to the Babinski sign. Avoidance and withdrawal responses interfere with the interpretation of the Babinski sign and can sometimes be overcome by utilizing alternative stimuli (e.g., squeezing the calf or Achilles tendon, flicking the fourth toe, downward scraping of the shin, lifting the straight leg, and others) or by having the patient scrape his own sole.
Absence of the superficial cutaneous reflexes of the abdominal, cremasteric, and other muscles are useful ancillary tests for detecting corticospinal lesions, particularly when unilateral.
Testing of Sensory Function
Because this part of the examination is attainable only through the subjective responses of the patient, it requires considerable cooperation. At the same time, it is subject to overinterpretation and suggestibility. Usually, sensory testing is reserved for the end of the examination and, if the findings are to be reliable, should not be prolonged. Each test should be explained briefly; too much discussion with a meticulous, introspective patient encourages the reporting of meaningless minor variations of stimulus intensity.
It is not necessary to examine all areas of the skin surface. A quick survey of the face, neck, arms, trunk, and legs with a pin takes only a few seconds. Usually one is seeking differences between the two sides of the body (it is better to ask whether stimuli on opposite sides of the body feel the same than to ask if they feel different), a level below which sensation is lost, or a zone of relative or absolute analgesia (loss of pain sensibility) or anesthesia (loss of touch sensibility). Regions of sensory deficit can then be tested more carefully and mapped. Moving the stimulus from an area of diminished sensation into a normal area is recommended because it enhances the perception of a difference. The finding of a zone of heightened sensation (“hyperesthesia”) also calls attention to a disturbance of superficial sensation.
The ability to perceive vibration may be tested by comparing the thresholds at which the patient and examiner lose perception at comparable bony prominences. We suggest recording the number of seconds for which the examiner appreciates vibration at the malleolus, toe, or finger after the patient reports that the fork has stopped buzzing. Joint position and the perception of movement of a digit can be tested by holding the body part at the sides and making small excursion at the adjacent joint.
Variations in sensory findings from one examination to another reflect differences in technique of examination as well as inconsistencies in the responses of the patient. Sensory testing is considered in greater detail in Chaps. 7 and 8.
Testing of Gait and Stance