Motor Exam I

1. Observation.

1. During the interview, observe the patient for abnormal movement. Observe for too little movement (hypokinesis), such as a masked facies, and for too much movement (hyperkinesis) such as tremor, tics, and chorea.
2. Answer questions like: Are tremors occurring at rest, as is typical of Parkinson's disease, or with action? Does the patient appear fidgety, or do they have choreiform movements? Is there a paucity of movement, as might be seen with Parkinsonian syndromes?

2. Bulk and fasciculations.

1. Carefully look at the patient's muscles in the upper and lower extremities for signs of atrophy. Atrophy of the intrinsic hand muscles may be seen with normal aging. Symmetry is also important. Generalized wasting or cachexia may be an indication of systemic disease, such as malignancy. Specific areas of atrophy are due to denervation of muscle tissue. Atrophy of the intrinsic foot muscles, along with high arches and hammertoes, may be a sign of peripheral neuropathy.
2. Note the presence of fasciculations, which are spontaneous quivering movements caused by firing of muscle motor units.
3. Look at for fasciculations that can be associated with generalized lower motor neuron disorders in the intrinsic hand muscles, shoulder girdle, and the thigh. Try gently tapping your fingers on the patient's muscles to elicit fasciculations.

3. Evaluation of the muscle tone.

1. Upper extremity tone.
   To test muscle tone, have the patient fully relaxed. One way to do this is by distracting the patient with conversation.
   1. While the patient is seated, passively move each upper extremity at several joints to get a feeling for any resistance or rigidity that may be present. Hold the forearm and the elbow, and move the arm through the full range of flexion and extension at the elbow. Then take the hand as if to shake it, and hold the forearm. First pronate and supinate the forearm. Then roll the hand around at the wrist.
      Feel the patient's tone. Assess if the tone is normal, decreased (hypotonia) or increased (hypertonia). Two common patterns of pathologic hypertonia are spasticity and rigidity. Spasticity manifests as resistance to the initiation of passive movement followed by a decrease in resistance over the remaining range of passive motion, which is why it is often called a "clasp-knife response." Rigidity is increased tone that persists throughout the passive range of motion. This is sometimes termed "lead pipe" rigidity and is common with extrapyramidal diseases such as Parkinson's disease.
   2. Cogwheeling is a ratcheting movement (resembling a cogwheel) that can be indicative of Parkinsonism. To test for cogwheeling in the arms, tell the patient to relax. Distract the patient with questions or conversation, and then place your index and middle finger over the patient's biceps tendon, followed by passive extension and flexion of the patient's arm and simultaneous rotation of the wrist. Cogwheeling is accentuated by asking the patient to move the contralateral arm in circular motions.
      To test the muscle tone in the lower extremities, have the patient relax the legs while lying on the examination table.
2. Lower extremity tone
   1. With the patient in a supine position, place your hands behind the patient's knee, and lift the leg in a sudden motion. Observe if the heel drags along the bed. With normal muscle tone, the heel will drag along the surface of the bed. However, if there is an increased tone or spasticity, the foot may not make contact with the bed.
   2. Another technique for assessing the muscle tone in the lower extremities is to support the patient's thigh with one hand, while holding the foot with the other hand, and alternately extending and flexing the patient's knee and ankle. Note rigidity and spasticity (suggesting increased muscle tone), or flaccidity (indicating decreased tone).

4. Screening muscle testing.

There are simple tests to help screen for motor weakness, such as observing the patient while walking, and testing for pronator drift. These can help a physician determine any weakness (even subtle).

1. To test for pronator drift, tell the patient to raise the arms with palms up (like catching raindrops or using the hands to hold out a tray). In patients with true motor weakness, the weak arm is likely to pronate, flex at the elbow, and drift downwards. Cerebellar or parietal lesions can even result in an upwards or outwards drift, which may be confusing to an examiner. Non-physiologic weakness typically results in a "square drift" characterized by the arm falling perpendicularly down, usually occurring after a delay.
2. Observe the patient walking.
   1. Ask the patient to walk back and forth.
   2. Observe arm swinging for symmetry.
   3. Watch stride for equal transit time and stride length, comparing sides. Also assess if the patient has a narrow or wide base stance.
   4. To assess for subtle gait abnormalities or asymmetries, instruct the patient to first walk on the heels, and then walk on the toes.

5. Formal muscle testing.

When performing formal muscle testing, remember which spinal nerve roots innervate each muscle. During the examination, observe the patient performing the tests, and assess the muscle strength on the scale from 0 to 5 (Table 1). General principles for examining muscle strength include the following: encourage maximal effort, stabilize the joint and isolate muscle group across one joint, compare one side to the other, and look for patterns of weakness (e.g., upper motor neuron or proximal versus distal).

Table 1. Muscle straight scale. A table of the scoring system (from 0 to 5) used for describing muscle strength in clinical practice.

1. Examination of upper extremities. Perform the test of strength in upper extremities with the patient sitting.
   1. Arm abduction at shoulder is controlled by the deltoid muscle, which is innervated by the C5 and C6 nerve roots and the axillary nerve.
      To test deltoids, ask the patient to raise both arms outward (abduction), and instruct the patient to resist the movement as you push down on the outstretch arms. As you perform the maneuver, assess the muscle strength on the given scale (Table 1).
   2. Arm flexion at the elbow is the work of the biceps muscle, which is innervated by C5 and C6, the musculocutaneous nerve.
      To test the biceps function, ask the patient to flex an arm ("make a muscle") and resist the movement as you pull on the patient's hand. Test one side, then repeat on the other side to assess for symmetry.
   3. Arm extension at the elbow is controlled by the triceps muscle, which is innervated by C6 and C7, the radial nerve.
      To test the triceps function, ask the patient to extend an arm, starting with a flexed position against the resistance you provide. Again, test one arm at a time.
   4. Wrist extensors are innervated by C6 and C7, via the radial nerve.
      To test wrist extensors, ask the patient to extend the right wrist while you push down against the back of the patient's hand ("cock your wrist back and don't let me pull it down"). Repeat on the left side, and compare between the sides.
   5. Finger grip controlled by forearm flexors and the intrinsic hand muscles is innervated by C7 and C8, via median and ulnar nerves.
      To test for grip strength, the patient should squeeze two of the examiner's fingers as hard as possible, while you try to remove your fingers from the patient's grasp. If the patient has normal grip strength, you will have difficulty removing your fingers. Test both sides simultaneously. Testing grip strength can be done for screening, but is unreliable as the sole test for weakness.
   6. Finger abduction is innervated by C8 and T1, via the ulnar nerve. The dorsal interossei muscles abduct the index, middle, and ring fingers while abductor digiti minimi abducts the pinky finger. These muscles are innervated by the ulnar nerve. To test finger abduction, have the patient "fan out" (spread) all fingers while you try to push them back together. Test both hands simultaneously, comparing between sides.
   7. Thumb opposition, which is controlled by the opponens pollicis muscle, is innervated by C8 and T1, the median nerve.
      To test thumb opposition, have the patient touch the tip of one thumb to the pinky on the same hand, while you attempt to pry the patient's finger out with your index finger. The opponens pollicis muscle may be weak in patients with carpal tunnel syndrome.
2. Examination of the lower extremities. Test the patient's lower extremities in a supine position.
   1. Hip flexion - a function of the iliopsoas muscle innervated by L2, 3, 4, femoral nerve.
      To test hip flexion, ask the patient to raise a thigh while you try to push it down with your palm. Repeat on the other side and compare.
   2. Hip adduction - mediated by L2, L3, L4, via the obturator nerve. The muscles involved include: obturator externus, adductor longus, magnus, and brevis and the gracilis muscles
      To test hip adduction, tell patient to bring the knees together while you provide resistance.
   3. Hip abductors (the gluteus medius and minimus muscles) are innervated by L4, L5, and S1, via the superior gluteal nerve.
      To test hip abduction, tell the patient to spread the knees apart while you place your hands on the outside of the knees, providing resistance.
   4. Hip extension is controlled by the gluteus maximus, which is innervated by L5, S1, and S2, via the inferior gluteal nerve.
      Test hip extension with the patient lying supine (on the back) with a leg extended at the knee, and place your hand under the patient's lower leg. Then ask the patient to press down against your hand.
   5. Knee extension by the quadriceps muscle is controlled by the L2, L3, and L4 nerve roots via the femoral nerve.
      Test knee extension by putting one hand under the patient's knee, and your other hand on top of the patient's lower leg. Provide resistance while the patient attempts to extend the lower leg.
   6. Knee flexion by the hamstrings muscle is innervated by L5, S1, and S2, through the sciatic nerve.
      Test knee flexion by placing one hand on the knee and the other under the ankle, and tell the patient to pull her leg in as hard as possible while resisting at the ankle.
   7. Ankle dorsiflexion by the tibialis anterior muscle is innervated by the L4 and L5 nerve roots via the peroneal nerve.
      To test ankle dorsiflexion, hold the top of the patient's foot and tell the patient to pull her foot up toward her head as hard as possible, while you try to resist the movement.
   8. Ankle plantar flexion by the gastrocnemius and soleus muscles is innervated by the S1 and S2 nerve roots via the tibial nerve.
      Place a hand under the ball of the patient's foot, and instruct the patient to press down as hard as possible ("like stepping on the gas") against your resistance.
   9. Finally, toe extension by extensor halucis longus muscle is almost completely innervated by the L5 nerve root.
      Ask the patient to move the large toe upwards, towards the patient's head, while you provide resistance resistance.