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Neurologic Examination

By

Michael C. Levin

, MD, College of Medicine, University of Saskatchewan

Last full review/revision Jul 2021| Content last modified Jul 2021
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Topic Resources

When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the neurologic examination—includes evaluation of the following:

Doctors may evaluate some areas more thoroughly than others depending on what type of disorder they suspect.

The neurologic examination can also help identify the cause of a muscle malfunction (such as weakness or paralysis) because normal muscle contraction depends on stimulation by a nerve (see figure Using the Brain to Move a Muscle Using the Brain to Move a Muscle Weakness refers to loss of muscle strength. That is, people cannot move a muscle normally despite trying as hard as they can. However, the term is often misused. Many people with normal muscle... read more ).

A neurologic examination differs from a psychiatric examination, which focuses on a person's behavior. However, the two examinations overlap somewhat because abnormalities in the brain can cause abnormal behavior. Abnormal behavior can be a clue to a physical problem in the brain.

Mental Status

Doctors evaluate the following:

  • Attention

  • Orientation to time, place, and person

  • Memory

  • Various abilities, such as thinking abstractly, following commands, using language, and solving math problems

  • Mood

The mental status evaluation consists of a series of questions and tasks, such as naming objects, recalling short lists, writing sentences, and copying shapes. The person’s answers are recorded and scored for accuracy. If the person reports feeling depressed, doctors ask if there have been any thoughts of suicide.

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Cranial Nerves

There are 12 pairs of cranial nerves Overview of the Cranial Nerves Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing... read more , which connect the brain with the eyes, ears, nose, face, tongue, throat, neck, upper shoulders, and some internal organs (see table Viewing Cranial Nerves Viewing the Cranial Nerves Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing... read more ). How many nerves doctors test depends on what type of disorder they suspect. For example, the 1st cranial nerve (the nerve of smell) is not usually tested when a muscle disorder is suspected, but it is tested in people recovering from serious head trauma (because smell is often lost).

A cranial nerve may be damaged anywhere along its length as a result of any of the following:

  • An injury

  • Impaired blood flow

  • An autoimmune disorder

  • A tumor

  • An infection

The exact site of the damage can often be identified by testing the functions of a particular cranial nerve.

Motor Nerves

Motor nerves carry impulses from the brain and spinal cord to voluntary muscles (muscles controlled by conscious effort), such as muscles of the arms and legs. Muscle weakness or paralysis of a muscle may indicate damage to any of the following:

Doctors look for abnormalities such as the following:

The doctor inspects the muscles for size, unusual movements, tone, strength, and dexterity.

Change in muscle size

A muscle wastes away (atrophies) when the muscle or the nerves supplying it are damaged or when the muscle has not been used for months for other reasons (such as being in a cast).

A muscle may increase in size (hypertrophy) because it is working harder to compensate for the weakness of another muscle. Muscles can appear to increase is size when normal muscle tissue is replaced by abnormal tissue, as occurs in amyloidosis Amyloidosis Amyloidosis is a rare disease in which abnormally folded proteins form amyloid fibrils that accumulate in various tissues and organs, sometimes leading to organ dysfunction, organ failure, and... read more Amyloidosis and some inherited muscle disorders (such as Duchenne muscular dystrophy Duchenne Muscular Dystrophy and Becker Muscular Dystrophy Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle structure and function are defective, leading to muscle weakness of varying... read more ). The abnormal tissue increases the apparent size but not the strength of the muscle.

Involuntary movements

Involuntary movements may indicate damage in the areas of the brain (basal ganglia) that control motor coordination.

Muscle tone

To evaluate muscle tone, doctors first ask the person to completely relax muscles in a limb. Then doctors move the person’s limb to determine how much the relaxed muscle involuntarily resists being moved—called muscle tone. How muscle tone reacts to being moved suggests possible causes, as follows:

Flaccidity may be present for a short time after an injury that causes paralysis, such as a spinal cord injury. When flaccidity results from such a spinal cord injury, muscle tone often gradually increases over days to weeks, eventually resulting in spasticity.

If people are afraid or confused during the examination, they may not be able to relax the muscles. In such cases, muscle tone may vary, making it hard for doctors to evaluate.

Muscle strength

Doctors test muscle strength by asking the person to push or pull against resistance or to do maneuvers that require strength, such as walking on the heels and tiptoes or rising from a chair. Doctors then rate muscle strength from 0 (no muscle contraction) to 5 (full strength).

Sometimes muscle weakness Weakness Weakness refers to loss of muscle strength. That is, people cannot move a muscle normally despite trying as hard as they can. However, the term is often misused. Many people with normal muscle... read more is evident when a person uses one limb more than another. For example, a right-handed person may gesture mostly with the left hand during a conversation. A weak arm may swing less while walking or drift downward when the arms are held up and the eyes are closed.

Knowing which body parts are weak (the pattern of weakness) can help doctors identify what the problem is, as in the following cases:

Muscle weakness may also occur in other patterns, such as the following:

Sensory Nerves

Sensory nerves carry information from the body to the brain about such things as touch, pain, heat and cold (temperature), vibration, the position of body parts, and the shape of objects. Each of these senses can be tested. Abnormal sensations or reduced perception of sensations may indicate damage to a sensory nerve, the spinal cord, or certain parts of the brain.

Information from specific areas on the body’s surface, called dermatomes Dermatomes Nerve root disorders result from sudden or long-term pressure on the spinal nerve root. Nerve root disorders usually result from a herniated disk or osteoarthritis in the spine. These disorders... read more , is carried to a specific location (level) in the spinal cord, then to the brain. Thus, doctors may be able to pinpoint the specific level of damage to the spinal cord by identifying the areas where sensation is abnormal or lost.

Dermatomes

The surface of the skin is divided into specific areas, called dermatomes. A dermatome is an area of skin whose sensory nerves all come from a single spinal nerve root. Sensory nerves carry information about such things as touch, pain, temperature, and vibration from the skin to the spinal cord.

Spinal roots come in pairs—one of each pair on each side of the body. There are 31 pairs:

  • There are 8 pairs of sensory nerve roots for the 7 cervical vertebrae.

  • Each of the 12 thoracic, 5 lumbar, and 5 sacral vertebrae has one pair of spinal nerve roots.

  • In addition, at the end of the spinal cord, there is a pair of coccygeal nerve roots, which supply a small area of the skin around the tailbone (coccyx)

There are dermatomes for each of these nerve roots.

Sensory information from a specific dermatome is carried by sensory nerve fibers to the spinal nerve root of a specific vertebra. For example, sensory information from a strip of skin along the back of the thigh, is carried by sensory nerve fibers to the 2nd sacral vertebra (S2) nerve root.

Dermatomes

Sensation in the skin is tested. Usually, doctors concentrate on the area where the person feels numbness, tingling, or pain. The best screening test for loss of sensation involves touching the skin of the face, body, and all four limbs with a pin and a blunt object (such as the head of a safety pin) to see if the person can feel them and tell the difference between sharp and dull. Doctors test both sides of the body. If doctors detect loss of sensation in a specific area, they test nearby areas to estimate the extent of the loss. This approach enables them to determine the abnormality's location in the brain, spinal cord, or peripheral nervous system.

Gentle (light) touch is tested with a cotton wisp.

Temperature sense (the ability to feel hot and cold) is tested with a tuning fork. Both prongs are cold, so the examiner warms one of them slightly by rubbing it. Then each of the prongs is touched to the person's skin.

Vibration sense is also tested with a tuning fork. The fork is lightly tapped to make it vibrate. It is then placed on the joint of a finger to determine whether and how long the person feels the vibration.

To test position sense, doctors move the person’s finger or toe up or down and ask the person to describe its position without looking.

The ability to identify the shape of an object is tested by placing a familiar object, such as a key or safety pin, in a person's hand and asking the person to identify it without looking. Or doctors may trace letters or numbers on the palm of the person's hand and ask the person to identify them. If a person cannot identify them, the cortex of the brain (the outer layer of the cerebrum, the largest part of the brain) may be damaged. This part of the brain integrates and interprets sensory information from different sources.

Reflexes

A reflex is an automatic response to a stimulus. For example, the lower leg jerks when the tendon below the kneecap is gently tapped with a small rubber hammer. The pathway that a reflex follows (reflex arc) does not directly involve the brain. The pathway consists of the sensory nerve to the spinal cord, the nerve connections in the spinal cord, and the motor nerves back to the muscle.

Doctors test reflexes to determine whether all parts of this pathway are functioning. The reflexes most commonly tested are the knee jerk and similar reflexes at the elbow and ankle.

The plantar reflex may help doctors diagnose abnormalities in the nerve pathways involved in the voluntary control of muscles. It is tested by firmly stroking the outer border of the sole of the foot with a key or other object that causes minor discomfort. Normally, the toes curl downward, except in infants aged 6 months or younger. Having the big toe go upward and the other toes spread out is a sign of an abnormality in the brain or spinal cord.

Testing other reflexes can provide important information. For example, doctors learn the extent of injury in a comatose person by noting the following:

  • Whether the pupils constrict when light is shined on them (pupillary light reflex)

  • Whether the eyes blink when the cornea is touched with a wisp of cotton (corneal reflex)

  • How the eyes move when the person’s head is turned or when water is flushed into the ear canal (caloric testing)

  • Whether the person gags when the back of the throat is touched, for example, with a tongue depressor (gag reflex)

Doctors also check whether the anus tightens (contracts) when it is lightly touched (called the anal wink). If this reflex is present in a person paralyzed after a spinal cord injury, the injury may be incomplete, and the chance of recovery is better than if the reflex were absent.

Reflex Arc: A No-Brainer

A reflex arc is the pathway that a nerve reflex, such as the knee jerk reflex, follows.

  • A tap on the knee stimulates sensory receptors, generating a nerve signal.

  • The signal travels along a nerve to the spinal cord.

  • In the spinal cord, the signal is transmitted from the sensory nerve to a motor nerve.

  • The motor nerve sends the signal back to a muscle in the thigh.

  • The muscle contracts, causing the lower leg to jerk upward. The entire reflex occurs without involving the brain.

Reflex Arc: A No-Brainer

Coordination, Balance, and Gait

To test walking, doctors ask a person to walk normally and in a straight line, placing one foot in front of the other. Abnormalities may help identify which part of the nervous system is not functioning normally. For example, if a person takes wide, unsteady steps (called ataxia), the cerebellum may be damaged or malfunctioning. (The cerebellum is the part of the brain that coordinates voluntary movements and controls balance.)

To test coordination, doctors may ask the person to use the forefinger to reach out and touch the doctor’s finger, then the person’s own nose, and then to repeat these actions rapidly. The person may be asked to do these actions first with the eyes open, then with the eyes closed.

The Romberg test is done to test position sense. The person stands still with both feet together as close as possible without losing balance. Then the eyes are closed. If balance is lost, information about position from the legs may not be reaching the brain, usually because the nerves or spinal cord is injured. However, abnormalities may also result from malfunction of the cerebellum or the balance system in the inner ears or its connections with the brain

Autonomic Nervous System

The autonomic (involuntary) nervous system Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more Overview of the Autonomic Nervous System regulates internal body processes that require no conscious effort, such as blood pressure, heart rate, breathing, and temperature regulation through sweating or shivering. An abnormality of this system may cause problems such as the following:

Doctors may do a variety of tests, such as the following:

Blood Flow to the Brain

A severe narrowing of the arteries to the brain reduces blood flow and increases the risk of stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more . The risk is higher for people who are older, who smoke cigarettes, or who have high blood pressure, high cholesterol levels, diabetes, or disorders of the arteries or heart.

Blood pressure may be measured in both arms to check for blockages in the large arteries that branch off from the aorta. Such blockages sometimes result in stroke.

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Bell palsy is sudden weakness or paralysis of the muscles on one side of the face due to malfunction of the seventh cranial nerve. This nerve moves facial muscles, stimulates salivary and tear glands, detects tastes, and controls a muscle involved in hearing. Which of the following is often the first symptom of Bell palsy?
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