Bates’ Visual Guide to Physical Examination

18.5 Assessment of the Reflexes Video Transcript

Narrator: When assessing deep tendon reflexes, grade them on a scale from 0-4+. A grade of 0 reflex no response; 1+ indicates a somewhat diminished reflex; a 2+ shows greater movement than 1+ and is the average normal response; a 3+ reflex is brisker than average, but is still normal; 4+ reflex is a very brisk, hyperactive response. By definition, it must be accompanied by clonus; a rhythmic oscillation between flexion and extension.

Begin assessing deep tendon reflexes by testing the biceps reflex. The patient’s arm must be relaxed, partially flexed at the elbow and positioned with the palm down. Depress the biceps tendon with your thumb or index finger. Strike your thumb or finger briskly with the reflex hammer. You should feel the biceps muscle contract and see flexion of the forearm.

To assess the triceps reflex, flex the patient’s arm at the elbow with the palm toward the body and pull the arm slightly across the chest. Strike the triceps tendon above the elbow. Watch for contraction of the triceps muscle and extension at the elbow.

To elicit the supinator, or brachioradialis reflex, the patient’s forearm should rest on the abdomen or lap with the form partly pronated. When the patient is ready, strike the radius one to two inches above the wrist. Observe for flexion and supination of the forearm.

To test the knee reflex, locate the patellar tendon with the patient’s knee flexed. Briskly The tendon just below the patella. Note contraction of the quadriceps and look for quick extension of the knee. A hand on the anterior thigh lets you feel this reflex. Supporting both knees at once allows you to assess small differences between the reflexes of each knee.

Test the ankle reflex. If the patient is sitting, dorsiflex the foot at the ankle. Ask the patient to relax and strike the Achilles tendon. Watch for the plantar flexion at the ankle and note the speed of relaxation after the muscular contraction. If the patient is lying down, flex one leg at both hip and knee and rotate it externally so that the lower leg rests across the opposition. Then, dorsiflex the foot at the ankle and strike the Achilles tendon. Repeat this test on the opposite side.

If the knee and ankle reflexes seem hyperactive, test for ankle clonus. Support the knee in a slightly flexed position. With your other hand, dorsiflex and plantar flex the foot a few times and then sharply dorsiflex the foot and maintain it in dorsiflexion. Look and feel for sustained rhythmic oscillations between dorsiflexion and plantar flexion. In most normal people, the ankle does not show clonus. A few clonic beats may be seen and felt, especially when the patient is tense or has exercised.

Now turn to the cutaneous stimulation reflexes. To test these reflexes, lightly but briskly stroke each side of the abdomen from above T8-10 and below T10-12 (the umbilicus). You should see contraction of the abdominal muscles and sometimes deviation of the umbilicus toward the stimulus.

To test for plantar response, use an object such as the wooden end of an applicator stick or the handle of your reflex hammer to stroke the lateral aspect of the soul of the foot from the heel to the ball, curbing immediately across the ball. Warn the patient that the stimulus may feel uncomfortable. Use the lightest stimulus that will provoke a response. Note this patient’s normal response, plantar flexion (or down going) of the big toe.

Some patients withdraw from the stimulus by flexing the hip in the knee. Hold the ankle if necessary to complete your observation.

It is sometimes difficult to distinguish withdrawal from a Babinski response. Dorsiflexion of the big toe (or a positive Babinski sign) is a pathological response which, as simulated here, manifests itself in dorsiflexion (or up going) of the big toe in conduction with fanning of the other toes. A positive test indicates a corticospinal tract lesion seen in a stroke.

If you suspect meningeal inflammation, test form meningeal signs. First make sure there is no injury to the cervical vertebrae or cervical cord. With the patient lying down, place your hands behind the patient’s head and flex the neck forward until the chain touches the chest if possible. There should be no resistance or pain. As you flex the patient’s neck, watch his hips and knees. Normally they should remain relaxed and motionless. Hip and knee flexion with this maneuver is a positive Brudzinski sign.

Flex one of the patient’s legs at the hip and knee and then straighten the knee. This action normally produces discomfort behind me during extension but should not cause pain. Pain and resistance to knee extension is a positive Kernig sign.

For low back pain with nerve pain that radiates down the leg (commonly called sciatica) in the S1 distribution, test straight leg raising for lumbosacral radiculopathy. Raise the supine patient’s relaxed and straightened leg, flexing the leg at the hip. Then dorsiflex the foot at an angle of about 60°. Radicular pain into the leg constitutes a positive test. Do not mistake normal tightness or discomfort in the buttocks or hamstring muscles as a positive test.