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Neurologic Examination

Todd A. Zelczak, OD, FAAO

11304 Montgomery Road
Cincinnati, Ohio 45249

 

Contents

 

Evaluation of Motor Functions

Evaluation of the motor system is divided into the following components.

1. Observation
2. Inspection
3. Palpitation
4. Muscle tone testing
5. Functional testing
6. Strength testing of individual muscle groups

The first step in evaluating a patient's motor system involves careful observation of the patient. In addition to posture, note any twitches, tremors, or involuntary movements. Next, inspect several individual muscles to see if muscle wasting, hypertrophy, or fasciculations (spontaneous quivering movements caused by firing of muscle motor units) are present. In cases of suspected myositis, it is appropriate to palpate the muscles to check for tenderness.

To assess muscle tone, ask the patient to relax, and then passively move each limb at several joints to evaluate any resistance or rigidity that may be present.

Functional testing can often help to detect subtle abnormalities. For example, drift can be assessed by having the patient close his/her eyes and extend both arms to the front with palms up. Observe the arms to determine if one or both drift downward to side. It is also possible to assess the patient's fine movement control by asking him/her to make rapid hand movements or tap a foot rapidly.

Finally, during a complete neurologic examination, test the strength of each muscle group and record it in a systemic fashion (Table 4).

 

Table 4. Rating Scale for Evaluation of Muscle Strength. From Stephen Russell, Marc Triola. The Precise Neurological Exam. NYU School of Medicine

 

Although muscle weakness is a fairly non-localizing finding that can be caused by disturbances in several aspects of the nervous or muscular systems, many components of the motor exam can help to distinguish between upper motor and lower motor neuron lesions (Table 5).



Table 5. Signs of Upper and Lower Motor Neuron Lesions. From Blumenfeld, An Interactive On-Line Guide to the Neurologic Examination.

 

To screen for muscle weakness, perform tests that will assess both upper and lower extremity strength (Fig. 20). For example, have the patient flex and extend both arms and legs against resistance. Record any weakness of one limb when compared to the contralateral limb.



FIGURE 20. Evaluation of motor function. Asking the patient to raise both arms in front of them while the examiner provides resistance tests upper extremity muscle strength.


Evaluation of Reflexes

A neurologic exam should include an evaluation of reflexes. Examples can include deep tendon reflexes (patellar tendon), plantar response (Babinski's sign), and finger flexors (Hoffmann's sign). When testing, note that reflexes can be influenced by age, metabolic factors such as thyroid dysfunction or electrolyte abnormalities, and anxiety of the patient.

Of the many reflex tests to choose from, the patellar tendon (knee-jerk) reflex test is commonly used. To perform this test, have the patient sit on the edge of a table or chair and dangle the feet. The examiner's hand is placed on the patient's quadriceps muscle and the patellar tendon is struck with a reflex hammer. It should be possible to feel the quadriceps contract and the knee extend when the patellar tendon is struck (Fig. 21). Certain cerebellar injuries can result in abnormal knee-jerk responses. Loss of deep tendon reflexes can also be associated with Adie's tonic pupil and reflex tests are mandatory in patients presenting with light-near dissociation pupils.



FIGURE 21: Evaluation of deep tendon reflexes. With the lower leg hanging freely off the end of the chair, the "knee-jerk" reflex is tested by striking the patellar tendon directly with the reflex hammer.

 

Evaluation of Coordination and Gait

Examinations of coordination and gait are used for testing cerebellar function (the cerebellum coordinates muscle actions to produce organized activities such as walking). To test coordination, evaluate the patient's ability to perform rapidly alternating and point-to-point movements. For example, ask the patient to place her/his hands on their thighs and then rapidly turn the hands over and lift them off the thighs. Once the patient understands this movement, tell him/her to repeat it rapidly for 10 seconds.

Next, the examiner can hold his/her index finger at arms length from the patient. The patient is asked to touch his/her own nose with their index finger (Fig. 22) and then to touch the examiner's finger (Fig. 23). This movement is repeated several times with the patient's eyes open and then with them closed. Nose to finger touching is an example of a point-to-point movement. A patient with a disorder of the cerebellum tends to overshoot the target (past pointing).

 

 


FIGURE 22 and 23. Evaluation of cerebellar function. While the examiner holds his finger at arm's length from the patient, the patient touches her nose and then touches the examiner's finger. After several sequences, the patient is asked to repeat the exercise with her eyes shut. A patient with a cerebellar disorder tends to overshoot the target.

 

Gait can be evaluated by having the patient walk across the room under observation. Watch for normal posture and coordinated arm movements. Next, ask the patient to walk heel to toe (Fig. 24) across the room, to walk on their toes to test for plantar flexion weakness, and finally to walk on their heels to test for dorsiflexion weakness. Abnormalities in heel to toe walking may be due to ethanol intoxication, weakness, poor position sense, vertigo, and/or leg tremors. These causes must be excluded before poor balance can be attributed to a cerebellar lesion. Most elderly patients have difficulty with tandem gait (heel to toe walking) due to general neuronal loss impairing a combination of position sense, strength, and coordination.



FIGURE 24. Examination of gait. Heel to toe walking (tandem gait)

 

Another convenient test for cerebellar function is the Romberg test. Have the patient stand with heels and toes together. Ask the patient to remain still and close their eyes. To achieve balance, a person requires at least two out of three of the following: 1) visual confirmation of position, 2) non-visual confirmation of position (including proprioceptive and vestibular input), and, 3) a normal functioning cerebellum. Therefore, if a patient loses balance after standing still with their eyes closed, but maintains balance with their eyes open, then there is likely to be a lesion in the cerebellum. This is a positive Romberg test (Fig. 25).



FIGURE 25. The Romberg test. Have the patient stand still with heels and toes together. Ask the patient to close her eyes and balance herself. If the patient loses her balance, the test is positive.


Evaluation of Sensory Functions

The neurologic evaluation should include tests for the primary senses of touch, pain, and vibration. Causes of sensory disturbances include diabetes mellitus, thiamine deficiency, neurotoxin damage, and spinal cord lesions. Affected patients can report paresthesias (pins and needles), dysesthesias (pain), as well as sensory loss, usually in the hands and feet.

To evaluate tactile sense, the patient's fingers and toes are lightly touched with a tissue (Fig. 26). With their eyes closed, patients are asked to identify when they feel the stroke of the tissue.



FIGURE 26. Evaluation of tactile sense. The patient is asked to close her eyes while fingers and toes are lightly touched with a tissue.

 

To test for pain sensation, touch the patient on the fingers and hand with a safety pin (Fig. 27). Alternate the sharp tip with the blunt end (Fig. 28) to determine whether the patient can discern the difference between sharp and dull sensations. Repeat this test on the patient's toes.

 

 


FIGURE 27 and 28. Evaluation of pain sense. Patient is asked to close her eyes. The examiner randomly alternates touching the patient (fingers and toes) with the sharp and dull ends of a paper clip (or safety pin) while the patient identifies the stimulus.

 

Vibration sense is tested by striking a tuning fork and placing it over the base of the nail bed on the patient's index finger. The examiner should place his/her index finger under the patient's to feel the vibration. Ask the patient when he/she no longer feels the vibration. For each test, comparison should be made from one side of the body to the other on each extremity. A significant finding during testing is a marked decrease in sensitivity.

 

Conclusion

The neurologic exam remains a valuable tool for the detection of intracranial lesions and nervous system disorders. Mastering the neurologic exam and utilizing its value takes practice, experience and a basic understanding of neuroanatomy. As the scope of optometry continues to grow, optometrists must continue to expand their knowledge to meet the needs of the primary care patient. This knowledge enables optometrists to co-manage and communicate with primary care physicians, as well as other healthcare specialists, and to better participate as a member of the medical community.

 

References

Muchnick, BG.: Clinical Medicine in Optometric Practice, St Louis, 1994, Mosby.

Lee, DA, Higginbotham, EJ: Clinical Guide to Comprehensive Ophthalmology, New York, 1999, Thieme.

Goldberg S: The Four Minute Neurologic Exam, Miami, 1987, Medmaster, Inc.

Leigh RJ, Zee, DS: The Neurology of Eye Movements, Philadelphia, 1991, F. A. Davis Co.

Weiner WJ, Goetz CG, editors: Neurology for the Non-Neurologist, Philadelphia, 1981, Harper and Row.

Hurst LP, editor: Medicine for the Practicing Physician, 4th edition, Stamford, Conn., 1996, Appleton & Lange.

 

 

 

 
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