Assessing the sensory system

• Assess the sensory system for light touch, pain, temperature, proprioception, vibration, anddiscriminative sensation (stereognosis).
• Have the patient close their eyes for this testing.
• For pain, temperature, and touch sensation, compare distal to proximal areas of the extremities, and scatter the stimuli.
  • Light touch
    • Use a fine wisp of cotton and touch the skin lightly. Ask the patient to respond when a touch is felt.
  • Pain
    • Use the stick portion of a broken cotton swab, or other suitable tool.
    • Occasionally, substitute the blunt end for the point. Ask, “Is this sharp or dull?” or, “Does this feel the same as this?”
    • Apply the lightest pressure needed.
  • Temperature
    • This is often omitted if pain sensation is normal, however if sensory deficits are noted, you can use a tuning fork warmed or cooled by running water and ask the patient to identify “hot” or “cold.”
  • Proprioception
    • Holding the patient’s big toe by its sides between your thumb and index finger, then move it gently away from the other toes. Demonstrate “up” and “down” as you move the patient’s toe clearly upward and downward. Then, ask the patient to say “up” or “down” when moving the large toe.
  • Vibration
    • Using a tuning fork, tap the prongs on the heel of your hand and place the base firmly over a distal interphalangeal joint of the patient’s finger, then over the interphalangeal joint of the big toe. Ask what the patient feels. If it’s unclear whether the patient is feeling pressure or vibration, ask the patient to tell you when the vibration stops; then touch the tuning fork to stop it from vibrating.
  • Stereognosis
    • Place a familiar object (for example, a coin, paper clip, key, or cotton ball) in the patient’s hand and ask the patient to tell you what it is.
    • If necessary, proceed with other methods of assessing discriminative sensations.

Assessing reflexes

• Elicit muscle stretchreflexes.
  • Biceps reflex
    • With the patient’s elbow partially flexed, and the forearm pronated, place your thumb or finger firmly on the biceps tendon. Strike the reflex hammer directly through your finger toward the biceps tendon.
    • Look for flexion at the elbow and contraction of the biceps muscle.
  • Triceps reflex
    • With the patient sitting or supine, flex the patient’s arm at the elbow, with palm toward the body, and pull it slightly across the chest. Strike the triceps tendon with a direct blow directly behind and just above the elbow. Watch for contraction of the triceps muscle and extension at the elbow.
    • You can also elicit this reflex by supporting the upper arm and asking the patient to let the arm go limp. Then strike the triceps tendon.
  • Brachioradialis reflex
    • With the patient’s hand resting on the abdomen or the lap, and the forearm partly pronated, strike the radius with the point or flat edge of the reflex hammer, about 2 to 4 inches above the wrist. Watch for flexion at the elbow and supination of the forearm.
  • Quadriceps (patellar) reflex
    • With the patient sitting or lying down, make sure the knee is flexed, and briskly tap the patellar tendon just below the patella. Note contraction of the quadriceps with extension at the knee.
  • Achilles (ankle) reflex
    • With the patient’s foot dorsiflexed at the ankle, strike the Achilles tendon and watch and feel for plantar flexion at the ankle.
    • If the reflexes seem hyperactive, test for ankleclonus.
• Elicit cutaneous or superficial stimulation reflexes.
  • Abdominal reflexes
    • With the patient supine, lightly, but briskly stroking each side of the abdomen toward the umbilicus. Note the contraction of the abdominal muscles and movement of the umbilicus toward the stimulus.
  • Plantar reflex
    • Stroke the lateral aspect of the sole from the heel to the ball of the foot, curving medially across the ball. Observe movement of the big toe, normally plantar flexion.
  • Anal reflex
    • Using the broken end of an applicator stick, lightly stroke the anus on both sides. Watch for reflex contraction of the external anal sphincter.

PEARLS

• Patients with Parkinson disease may have a slow, “pill-rolling” tremor at rest.
• Fasciculations with atrophy and muscle weakness suggest peripheral motor neuron disease.
• Remember that when testing muscle strength, the patient’s dominant side is usually slightly stronger than the nondominant side.
• When assessing vibration and position sense, test the fingers and toes first. If these are normal, you may safely assume that more proximal areas will also be normal.
• When testing the plantar response, dorsiflexion of the big toe is a positive Babinski response, arising from a CNS lesion affecting the corticospinal tract. It may be transiently positive in unconscious states from drug or alcohol intoxication and during the postictal phase.