Motor Function and Cerebellar Testing

To evaluate the central and peripheral nervous systems, you must assess motor functions related to the spinal nerves, spinal column, cerebellar function, and the brain.

Together, the motor system and the cerebellum have several functions including maintaining muscle tone, muscle strength, movement, coordination, and balance. Specific to motor function, the spinal nerves innervate all portions of the body from the neck down to the toes and transmit sensory information to the cerebellum and brain (via afferent nerves) and to all areas of the body (via efferent nerves). The cerebellum relies on effective functioning of the musculoskeletal system, but is specifically responsible for coordination of movement. Cerebellar dysfunction can result in ataxia and is associated with incoordination, tremors, and difficulty with rapid and fine motor movements, as well as walking and balance. An abnormal finding associated with motor function and cerebellar testing could indicate a problem with the spinal nerves, spinal column, cerebellum, or the brain. These findings should be considered in the context of a complete neurological assessment.

The following assessment is completed to evaluate motor function and cerebellar testing.

1. Inspect and palpate skeletal muscles of limbs for bulk (size), symmetry, and involuntary movements. Note any abnormalities such as atrophy, asymmetry, and twitches. For more information, refer back to the chapter on musculoskeletal assessment.
2. Assess ROM and manual muscle testing. Note any abnormalities such as asymmetry, decreased ROM, decreased muscle resistance (including flaccid/atonic), and increased muscle resistance/hypertonia (including rigidity and spasticity). Recall the techniques presented in the objective section of the musculoskeletal testing resource.
3. Assess pronator drift by asking the client to close their eyes while extending their arms straight out in front of them with palms of hands facing upward (supination) for about 30 seconds. This can be done in a sitting or standing position.
   • Normally, the client should be able to maintain this position.
   • Pronator drift is when one forearm begins to pronate, move downward, and sometimes the elbow begins to flex (this finding may be associated with upper motor neuron diseases of the brain and spinal cord). See Video 15 demonstrating pronator drift and an abnormal finding: the left arm lowers and shifts from supination to pronation.

Video 15: Pronator drift.

4. Use the past pointing test as previously described related to CN VIII – Vestibulocochlear Nerves.
5. Similar to pronator drift, you can assess lower extremity weakness by having the client lie in a supine position with head on a pillow. Ask them to flex their knees as they keep their feet flat on the exam table for about 30 seconds (see Video 16).
   • Normally, the client should be able to maintain this position.
   • An abnormal finding is when one leg begins to extend out.

Video 16: Lower extremity weakness test.

6. To perform the Romberg test, ask the client to remove their shoes. Ask them to stand at the bedside in case they get dizzy and need to sit down; you can also stand near them for safety. Next, ask the client to move their feet together with their arms/hands down at their sides or crossed in front of them. Start by asking the client to stand in this position for 20 seconds with their eyes open to ensure balance (and cerebellar functioning). Next, ask the client to maintain this position with their eyes closed for up to one minute (this tests proprioception, i.e., one’s location in space). See Figure 16.

1. • Normally, the client should be able to maintain this position with eyes opened and eyes closed, possibly with mild swaying.
   • An abnormal or positive finding is unusual swaying or moving their feet: this may be associated with the posterior column of the spinal cord. If the swaying happens when eyes are opened, this finding may be associated with the cerebellum.

Figure 16: Romberg test.

7. Assessment of posture and gait can be done in several ways. At this point, you have probably already evaluated the client’s ability to sit or stand as part of the Brief Scan of the Neurological System. Now, ask the client to walk from point A to point B (usually about 20 feet/6 metres) and then turn around and walk back to point B. To emphasize any balance or coordination issues, ask the client to walk in a heel-to-toe manner for about half the distance (10 feet/3 metres). See Video 17

• • Normally the client should be able to sit or stand upright with their head up and in a midline position, maintain their balance, and walk smoothly in a coordinated manner with their arms swinging at their sides.
  • Abnormal findings include inability to sit upright, drooping of head, lack of balance, wide stance, incoordination of legs and arms when walking, or lack of arm movement.

Video 17: Gait test.

8. To further test coordination and cerebellar function, complete the finger-to-nose and finger-to-finger test; the client may be sitting or standing for these tests. For the finger-to-nose test, ask the client to extend both arms out to the sides and then bend one arm slowly to touch their nose with their index finger, alternating with each arm a 3 to 4 times. Next, ask the client to close their eyes and repeat the same movements more quickly, about 3 to 4 times. Then, ask them to open their eyes. For the finger-to-finger test, place your finger an arm’s length away from them, ask them to touch it with their index finger, then touch their nose, and repeat this activity 3-4 times moving your finger to a new location each time (in a high, middle and low location). Repeat with the other arm. The heel-to-shin test is similar to this test but specific to lower extremities: ensure the client is in a supine position and ask them to place their heel on the contralateral shin at the knee level and slide their heel down the shin. Repeat for the other leg. See Video 18 for the finger-to-nose and finger-to-finger tests and Video 19 for the heel-to-shin test.
   • Normally, the client’s movement should be accurate and steady in motion.
   • Abnormal findings include inaccurate and unsteady movement.

Video 18: Finger-to-nose test and finger-to-finger test.

Video 19: Heel-to-shin test.

9. While the client is seated, perform rapid alternating movements of the upper and lower limbs. Start by asking the client to stick out one hand with the palm facing upward, then place the back of their other hand in this palm, and then turn the top hand over (palm to palm): repeat this process and increase the speed about 3–4 times. Repeat on the other side. See Video 20. Next, ask the client to remain seated with feet flat on the floor; ask them to repeatedly tap one of their feet on the floor and repeat this with increased speed (about 3–4 times is sufficient). Repeat for the other foot.
   • Normally, the client can repeat the action smoothly, quickly, and symmetrically.
   • Abnormal findings include slow and uncoordinated movements.

Video 30: Rapid alternating movements.

10. Note the findings:
    • Normal findings might be documented as: “Limb muscles symmetrical bilaterally with no atrophy, no involuntary movements, full range of motion, equal muscle resistance bilaterally. No pronator drift. No lower extremity weakness observed. Client able to maintain standing position with mild swaying with Romberg test. Smooth coordinated gait. Accurate and steady motion with finger-to-nose, finger-to-finger, and heel-to-shin test. Smooth, quick and symmetrical rapid alternating movements of hands and feet.”
    • Abnormal findings might be documented as: “Pronator drift observed right arm. Ataxia observed with walking and wide stance.”

Activity: Check Your Understanding

References

Campbell, W., & Barohn, R. (2020). DeJong’s The Neurological Examination. Wolters Kluwer.