ASSESSMENT OF THE NERVOUS SYSTEM

The nervous system consists of the central nervous system (CNS), the peripheral nervous system, and the autonomic nervous system. Together these three components integrate all physical, emotional, and intellectual activities. The CNS includes the brain and spinal cord. These two structures collect and interpret voluntary and involuntary sensory and motor signals. A brief overview of the anatomy and physiology of the CNS is provided.

Brain: The brain collects, integrates, and interprets all stimuli. It also initiates voluntary and involuntary motor activity. The brain is composed of three areas: the cerebrum, brain stem, and cerebellum.

Cerebrum: Divided into right and left hemispheres. Each hemisphere has four lobes: parietal, occipital, temporal, and frontal. The cerebral lobes control complex problem-solving; value judgements; language; emotions; interpretation of visual images; and interpretation of touch, pressure, temperature, and position sense.

Brain Stem: Composed of the midbrain, pons, and medulla. Is a major sensory and motor pathway for impulses running to and from the cerebrum. Regulates body functions such as respiration, auditory and visual reflexes, swallowing, and coughing.

Cerebellum: Lies in the posterior portion of the skull and contains the major motor and sensory pathways. It controls smooth, coordinated muscle movements and helps to maintain equilibrium.

Spinal Cord: The spinal cord is the primary pathway for messages traveling between the peripheral areas of the body and the brain. It also houses the reflex arc for actions such as the knee-jerk reflex.

The manner in which you progress with your neurological assessment depends upon the patient’s level of consciousness. To perform a complete neurological exam on the patient, he/she must be able to cooperate.

Health History Assessment

A neurological health history can be obtained if the patient is alert enough and oriented to person, place, and time. If the person appears to be disoriented or confused upon questioning, ask family members and friends to confirm the information.

The person should be questioned as to previous history of seizures, loss of consciousness, anesthesia (an absence of normal sensation – especially to pain), paresthesia (numbness and tingling; a “pins and needles” feeling), neuralgia, twitches, tremors, personality changes, memory deficits, mental deterioration, nervousness, anxiety, history of psychiatric problems, vertigo, sensory disturbance, phobias, hallucinations, delusions, illusions, nightmares, insomnia, and/or grandiose ideas.

Differences Among Hallucinations, Delusions, and Illusions

Hallucinations: A sensory perception not resulting from external stimuli. An example would be someone who is hearing voices.

Delusions: A persistent belief even though illogical. An example would be someone who is feeling controlled by external sources.

Illusions: A false interpretation of external stimuli. Examples of illusions inlcude seeing mirages or hearing the ocean in a sea shell.

Physical Assessment

A complete neurologic assessment consists of five steps: o Mental status exam o Cranial nerve assessment o Reflex testing o Motor system assessment o Sensory system assessment

Mental Status Exam

The mental status exam really assesses the patient’s cerebral function. Remember that the cerebrum controls sophisticated mental functions such as speech, problem solving, and memory. As you perform this portion of the neurological assessment, pay special attention to the patient’s speech and language abilities. His speech should be clear, coherent, and spoken at an appropriate rate. The language used should be appropriate for the education and socioeconomic levels of the person. Altered speech patterns can alert you to the possibility of neurologic problems.

Intellect: (Memory, Orientation, Recognition, Calculations)

Orientation: Assess time, place, person. Organic brain disorders lose time first, then place, rarely person.

Attention span: Should be able to focus on examiner’s questions and respond. Impaired in anxiety, fatigue, intoxication.

Recent memory: Ask for 24 hour diet recall and other easily verifiable information. Impaired in organic brain syndromes and Alzheimer’s.

Remote memory: Ask for past health, birthdays, anniversary, relevant history. Lost in Alzheimer’s, cortical injury, but not in normal aging or most organic brain syndromes.

New learning: Assess 4-word recall (should be able to recall all four at 10 minutes and three words at 30 minutes). Use the word groups “brown, honesty, tulip, eyedropper” or “fun, carrot, ankle, loyalty”. Four-word recall is impaired in Alzheimer’s, anxiety, and depression.

Judgement: Ask questions such as “What would you do if your house caught fire?” or “What are your plans for the future?”. Judgement is impaired in mental retardation, emotional dysfunction, schizophrenia, and organic brain disease.

Perception: Visual hallucinations are often associated with medications and organic syndromes. Auditory hallucinations are associated more with psychiatric disorders.

Cranial Nerve Assessment

The following guide will provide a quick overview of each cranial nerve’s function.

Cranial Nerve Assessment TechniquesCranial Nerve I (Olfactory)

After assessing patency of both nares, have client close eyes, obstruct one nare, and sniff. Use common, easily identifiable substances such as coffee, toothpaste, orange, vanilla, soap, or peppermint. Use different substances for each side. Bilateral decreased sense of smell occurs with age, tobacco smoking, allergic rhinitis, cocaine use. Unilateral loss of sense of smell (neurologic anosmia) can indicate a frontal lobe lesion.

Cranial Nerve II (Optic)

Check visual acuity (have the patient read newspaper print) and visual fields for each eye. Unilateral blindness can indicate a lesion or pressure in the globe or optic nerve. Loss of the same half of the visual field in both eyes (homonymous hemianopsia) can indicate a lesion of the opposite side optic tract as in a CVA.

Cranial Nerve III (Oculomotor)

Assess pupil size and light reflex. A unilaterally dilated pupil with unilateral absent light reflex and/or if the eye will not turn upwards could indicate an internal carotid aneurysm or uncal herniation with increased intracranial pressure.

Cranial Nerve IV (Trochlear) and Cranial Nerve VI (Abducens)

Have patient turn eyes downward, temporally, and nasally. If the eyes will not do this the patient may have a fracture of the eye orbit or a brain stem tumor. (Note: Cranial Nerves III, IV, and VI are examined together because they control eyelid elevation, eye movement, and pupillary constriction.)

Cranial Nerve V (Trigeminal)

Motor – Palpate jaws and temples while patient clenches teeth.

Sensory – Have patient close eyes, touch cotton ball to all areas of face.

Unilateral deficit seen with trauma and tumors.

Cranial Nerve VII (Facial)

Motor

Check symmetry and mobility of face by having patient frown, close eyes, lift eyebrows, and puff cheeks.

Sensory Asses the patient’s ability to identify taste (sugar, salt, lemon juice)

An asymmetrical deficit can be found in trauma, Bell’s palsy, CVA, tumor, and inflammation.

Cranial Nerve VIII (Acoustic or Vestibulocochlear)

This tests hearing acuity. Impairment indicates inflammation or occlusion of the ear canal, drug toxicity, or a possible tumor.

Cranial Nerve IX (Glossopharyngeal) and X (Vagus)

Motor

Depress the tongue with a tongue blade and have the patient say “ahh” or yawn. Uvula and soft palate should rise. Gag reflex should be present and the voice should sound smooth.

Deficits can indicate a brain stem tumor or neck injury.

Cranial Nerve XI (Spinal Accessory)

Have the patient rotate the head and shrug shoulders against resistance. If the patient is unable to do this it may indicate a neck injury.

Cranial Nerve XII (Hypoglossal)

Motor

Assess tongue control.

Wasting of the tongue, deviation to one side, tremors, and an inability to distinctly say l,t,d,n sounds can indicate a lower or upper motor neuron lesion.