Introduction to the
Central Nervous System

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A more complete and specific neurologic examination is necessary to confirm a diagnosis in a suspected neurologic disorder. Areas to be evaluated in such an examination include mental status, motor function, sensory function, and reflexes.

a. Mental Status.

Level of consciousness. The single most valuable indicator of neurologic function is the individual's level of consciousness. Determine the patient's level of consciousness -- alert, lethargic, stupor, semicoma, or coma.

NOTE: Legally, only physicians are authorized to make such determinations. You can legally describe the patient's condition in the nursing notes by saying, "appears to be" alert or lethargic or so forth.

  • Alert. The patient is awake and verbally and motorally responsive.
  • Lethargic. The patient is sleepy or drowsy and will awaken and respond appropriately to command.
  • Stupor. The patient becomes unconscious spontaneously and is very hard to awaken.
  • Semicoma. The patient is not awake but will respond purposefully to deep pain.
  • Coma. The patient is completely unresponsive.

Calculations in basic mathematics. Ask the patient to do some simple arithmetic problems without using paper and pencil. For example, ask him to add 7s or to subtract 3s backwards. It should take the patient of average intelligence about one minute to complete the calculations with few errors.

Affect/mood. During the physical part of the examination, note the patient's mood and emotional expressions which you can observe by his verbal and nonverbal behavior. Notice if he has mood swings or behaves as though he is anxious or depressed. Notice whether or not the patient's feelings are appropriate for the situation. Disturbances in mood, affect, and feelings may be indicated by a patient who exhibits unresponsiveness, hopelessness, agitation, euphoria, irritability, or wide mood swings.

Memory (recent and remote). Ask the patient his social security number, the city he is in, the building number, the state, and the names of two or three past presidents of the United States.

Knowledge (normal intellect). Ask the patient to name five large cities, major rivers, etc. Another way to test this area is to ask the patient to tell you the meaning of a fable, proverb, or metaphor. For example, explain:

  • Too many cooks spoil the soup.
  • A penny saved is a penny earned.
  • A stitch in time saves nine.

A person of average intelligence should be able to explain any of these phrases. A person who can't explain any of these phrases may have organic brain syndrome, brain damage, or lack of intelligence.

b. Cerebellar Functions. These include tests for balance and coordination. The cerebellum controls the skeletal muscles and coordinates voluntary muscular movement.

Finger-to-nose test. With his eyes open, instruct the patient to touch his index finger to his nose.

Rapid alternating movements test. Seat the patient. Instruct him to pat his knees with his hands, palms down then palms up. Have him alternate palms down and palms up rapidly. Watch the patient to notice if his movements are stiff, slow, nonrhythmic, or jerky. The movements should be smooth and rhythmic as he does the task faster.

Rom berg test. Instruct the patient to stand with his feet together and his arms at his side. Have the patient do this with his eyes open and then with his eyes closed. (Stand close to the patient to keep him upright if he starts to sway.) Expect the patient to sway slightly but not fall. This is a test of balance. If the patient really loses his balance, he may have cerebellar ataxia or vestibular dysfunction.

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Figure 2-1. The Romberg test for balance.

(4) Normal gait and heel-toe-heel walking. To check the patient for normal gait, have him walk around the examining room. He should walk in his gait with appropriate arm movements:

(a) The heel of one foot hits the floor, and then the foot is on the floor completely.

(b) The heel of the other foot pushes off and leaves the floor.

(c) The patient transfers his weight from the first heel to the ball of his foot.

(d) He swings the first leg faster as he takes his weight off his second foot.

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Figure 2-2. Normal gait.

(e) The second foot moves more slowly as it gets ready for his heel to strike the floor.

NOTE: In this process, observe whether the patient shuffles, places his feet too wide apart, walks on his toes, has foot flop and leg lag or scissoring, doesn't swing his arms, staggers, or reels. The way he walks should be smooth with a regular rhythm and a symmetric stride length. The trunk should sway slightly, and his arm swing should be smooth and symmetric.

c. Motor Function. Perform the following checks:

(1) Check for mild weakness. Have the patient stand with his arms outstretched, palms upward, eyes closed for 20 to 30 seconds. If one arm drops and the hand turns over slightly, he has mild weakness called the pronator sign.

(2) Check muscle tone. Instruct the patient to relax. If the patient is in bed, lift one of his limbs from the bed and watch it fall. When the patient sits on the edge of the examining table, the freedom with which the legs swing indicates the muscle tone.

(3) Check muscle strength. Instruct the patient to do the following:

(a) Ask him to grip your hands and squeeze.

(b) Have the patient push against your palm with his foot. Compare the strength of his muscles on each side of his body.

(c) Have the patient extend and flex his neck, elbows, wrists, fingers, toes, hips, and knees.

(d) Instruct him to extend his spine.

(e) Ask the patient to contract and relax his abdominal muscles.

(f) Have him rotate his shoulders.

(g) Instruct the patient to walk on his toes, then to walk on his heels.

NOTE: Test the patient bilaterally (comparing muscle strength on one side of the body with muscle strength on the other side of the body). Look for muscle atrophy (loss of muscle strength or muscle tone).

d. Cranial Nerves. Evaluating the cranial nerves is an important part of the neurologic examination. Taste and smell are usually not checked unless a problem is suspected in those areas. Test the patient's pupillary reflexes. This is commonly done by shining a light in the patient's eyes and comparing the eyes. The pupillary reflexes are abnormal if they do not respond to light or if the pupils respond unequally. If the pupillary reflex in both eyes are equal, write PERRLA (pupils equal round and reactive to light and accommodation). Instruct the patient to smile and raise his eyebrows. Look for weakness or drooping on either side of his face while he is smiling. Check to see if there is even movement of both eyebrows.

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Figure 2-3. Testing for pupillary reactions.

e. Sensory Function. Testing for sensory function is the most difficult and the least reliable part of the examination. Perform two tests.

(1) Test for pain. Perform this test using pin pricks in the arms and legs. Ask the patient to say "sharp" or "dull" after each stimulus and to reply immediately. This is a test of the patient's response to superficial pain. Usually, a sterile needle with a sharp point and dull hub on the other end is the instrument used. In a nonpredictable pattern, touch the patient's skin with one or the other end of the needle.

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Figure 2-4. Testing for pain.

(2) Test for touch. Touch the skin with a cotton ball using light strokes. Do not press down on the skin or touch areas of the skin that have hair. Instruct the patient to point to the area you have touched or tell you when he feels the sensation of being touched. (Obviously, he will not be watching you touch his skin.)

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Figure 2-5. Testing for touch.

f. Reflexes. A reflex may be defined as an immediate and involuntary response to a stimulus. A reflex is a fast response to a change in the body's internal or external environment in an attempt to restore homeostasis.

(1) Reflexes and diagnosis. Evaluation of a reflex can aid a doctor in diagnosing a problem. A reflex which stops functioning or functions abnormally may indicate that a particular conduction pathway in the body has been damaged. Testing internal organs for reflex is not practical for diagnosis, but somatic reflexes (reflexes resulting in the contraction of skeletal muscles) are excellent diagnostic tools.

(2) Superficial reflexes. Stroke the skin with a hard object such as an applicator stick. What is felt is a superficial reflex.

(3) Muscle reflexes. Muscle reflexes help determine how responsive the spinal cord is. If many impulses are transmitted from the brain to the spinal cord, the muscle reflexes become so sensitive that just tapping the tendon of the knee with the tip of your finger can cause the leg to jump a considerable distance. If, however, the cord is overwhelmed by other impulses from the brain, it may be impossible to cause the muscles or tendons to respond.

(4) Evaluation of neurological impairment. You can evaluate neurological impairment by testing reflexes using a stopwatch to time the reflex response. These are reflexes that are clinically significant:

(a) Biceps--deep tendon reflex.

1 Have the patient's elbow at about a 90 angle of flexion with the arm slightly bent down as shown in figure 2-6.
2 Grasp the elbow with your left hand so the fingers are behind the elbow and your abductee thumb presses the biceps brachii tendon.
3 Strike your thumb a series of blows with the rubber hammer, varying your thumb pressure with each blow until the most satisfactory response is obtained.
4 Normal reflex is elbow flexion (bending).

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Figure 2-6. Biceps reflex.

(b) Triceps--deep tendon reflex.

1 Grasp the patient's wrist with your left hand and pull his arm across his chest so the elbow is flexed about 90 and the forearm is partially bent down.
2 Tap the triceps brachii tendon directly above the olecranon process. The normal response is elbow extension.

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Figure 2-7. Triceps reflex.

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Figure 2-8. Triceps jerk with one arm flexed.

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Figure 2-9. Triceps jerk with arms folded.

(c) Plantar (Babinski) reflex. Lightly stimulate the outer margin of the sole of the foot to get this reflex. Perform the reflex check in this manner:

1 Grasp the ankle with your left hand.
2 Use a blunt point and moderate pressure and stroke the sole of the foot near its lateral border. Stroke from the heel toward the ball of the foot where the course should curve across the ball of the foot to the medial side, following the bases of the toes.
3 A normal reflex is for the patient to have plantar flexion of all his toes.
4 A completely abnormal reflex is indicated if there is dorsiflexion (turning upward) of the big toes, fanning of all toes, turning upward of the ankle, or flexion (bending) of the knee and hip.

NOTE: Those patients who are extremely ticklish may have a slightly abnormal reflex.

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Figure 2-10. Checking the plantar reflex.

(d) Patellar reflex (knee jerk). Test the reflex in this manner:

1 Have the patient sit on a table or high bed to allow his legs to swing freely.
2 Tap the patellar tendon directly with a rubber hammer.
3 Normally, the knee extends.

NOTE: If muscle centers in the second, third, or fourth lumbar segments of the spinal cord are damaged, the reflex may be blocked. People with chronic diabetes or neurosyphilis may not have that reflex.

4 Conduct the reflex check as shown in figure 2-12 if the patient must be lying down. Put your hand under the popliteal fossa and lift the patient's knee from the table or bed. Tap the patellar tendon directly.

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Figure 2-11. Patellar reflex (knee jerk).

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Figure 2-12. Patellar reflex (knee jerk) from a supine position.

(e) Achilles reflex (ankle jerk). Tap the Achilles tendon and the foot should extend from the contraction of the gastrocnemius and soleus muscles responding to that tap. Perform the reflex test in this manner:

1 Have the patient sit on a table or bed so that his legs dangle.
2 With your left hand, grasp the patient's foot and pull it in dorsiflexion (upward). Find the degree of stretching upward of the Achilles tendon that produces the optimal response.
3 Tap the tendon directly.
4 Normal response is contraction of the gastrocnemius and plantar flexion of the foot.

NOTE: If the normal response does not occur, there may be damage to the nerves supplying the posterior leg muscles or damage to the nerve cells in the lumbosacral region of the spinal cord. Individuals who do not have this response (the ankle jerk) include persons with chronic diabetes, neurosyphilis, alcoholism, and subarachnoid hemorrhages.

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Figure 2-13. Achilles reflex (ankle jerk).

5 If the patient must be in the supine position, perform the check in this manner. Partially flex the hip and knee, then rotate the knee outward as far as is comfortable for the patient. With your left hand, grasp his foot and pull the foot upward. Tap the Achilles tendon directly. The normal response is plantar flexion.

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