A look at neurologic disorders

Complex and infinitely diverse, the nervous system is the body’s internal communication network. It coordinates all body functions and all adaptations to changes in the body’s internal and external environments. Because of the intricacy and complexity of the nervous system, neurologic disorders can manifest in many ways.

Neurologic Disorders: Anatomy and physiology

The nervous system is divided into the central nervous system (CNS), the peripheral nervous system, and the autonomic nervous system. Through complex and coordinated interactions, these three parts integrate all physical, intellectual, and emotional activities.

Neurologic disorders: Central nervous system

The CNS includes the brain and the spinal cord, the two structures that collect and interpret voluntary and involuntary motor and sensory stimuli. (See The CNS.)

The CNS

Neurologic disorders

 

Brain

The brain consists of the cerebrum (cerebral cortex), the brain stem, and the cerebellum. It collects, integrates, and interprets all stimuli; in addition, it initiates and monitors voluntary and involuntary motor activity.

I think; therefore, I am

The cerebrum gives us the ability to think and reason. Within the skull, it’s enclosed in three membrane layers called meninges. If blood or fluid accumulates between these layers, pressure builds inside the skull and compromises brain function.

The cerebrum has four lobes and two hemispheres. The right hemisphere controls the left side of the body, and the left hemisphere controls the right side of the body. Each lobe controls and coordinates specific functions. (See The lobes of the cerebrum.)

The lobes of the cerebrum

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Regulatory affairs

A part of the cerebrum called the diencephalon contains the thalamus and hypothalamus. The thalamus relays sensory impulses and plays an important part in conscious pain awareness. The hypothalamus regulates many body functions, including temperature control, pituitary hormone production, appetite, thirst, and water balance.

Motoring up the path

Focus Topic: Neurologic Disorders

The brain stem is beneath the diencephalon and is divided into the midbrain, pons, and medulla. The brain stem contains the nuclei for cranial nerves III through XII. It relays messages between the cerebrum and diencephalon and the spinal cord; it also regulates automatic body functions, such as heart rate, breathing, swallowing, and coughing.

At the back of the brain

The cerebellum is located below the occipital lobes at the back of the brain and consists of two hemispheres. It facilitates smooth, coordinated muscle movement and equilibrium.

Spinal cord

The spinal cord is the primary pathway for nerve impulses traveling between peripheral areas of the body and the brain. It also contains the sensory-to-motor pathway known as the reflex arc. A reflex arc is the route followed by nerve impulses to and from the CNS in the production of a reflex action. (See Understanding the reflex arc.)

Understanding the reflex arc

Neurologic disorders

 

Where it is and what it’s got

Focus Topic: Neurologic Disorders

The spinal cord extends from the upper border of the first cervical vertebra to the lower border of the first lumbar vertebra. It’s encased by meninges, the same membrane structure as the brain, and is protected by the bony vertebrae of the spine. The spinal cord is made up of an H-shaped mass of gray matter, divided into the dorsal (posterior) and ventral (anterior) horns. White matter surrounds the horns.

What matter, white matter?

Focus Topic: Neurologic Disorders

Dorsal white matter contains ascending tracts that transmit impulses up the spinal cord to higher sensory centers. Ventral white matter contains descending motor tracts that transmit motor impulses down from the higher motor centers to the spinal cord.

Mapping the nerves

Focus Topic: Neurologic Disorders

Sensory (afferent) nerve fibers originate in the nerve roots along the spine — cervical, thoracic, lumbar, or sacral — and supply specific areas of the skin. These areas, known as dermatomes, provide a nerve “map” of the body and help when testing sensation to determine the location of a lesion.

Neurologic disorders: Peripheral nervous system

The peripheral nervous system includes the peripheral and cranial nerves. Peripheral sensory nerves transmit stimuli from sensory receptors in the skin, muscles, sensory organs, and viscera to the dorsal horn of the spinal cord. The upper motor neurons of the brain and the lower motor neurons of cell bodies in the ventral horn of the spinal cord carry impulses that affect movement. The 12 pairs of cranial nerves are the primary motor and sensory paths in the brain, head, and neck. (See Identifying cranial nerves.)

Identifying cranial nerves

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Neurologic disorders: Autonomic nervous system

The autonomic nervous system contains motor neurons that regulate visceral organs and innervate (supply nerves to) smooth and cardiac muscles and the glands. This nervous system has two parts:

  • the sympathetic portion, which controls fight-or-flight responses
  • the parasympathetic portion, which maintains baseline body functions (rest and digest)

Assessment

Conducting an assessment for possible neurologic impairment includes a thorough health history and an investigation of physical signs of impairment.

History

Begin by asking the patient what brings him to seek care at this time. Gather details about his current health, previous health, family health, and lifestyle. Also, perform a complete systems review. It’s best to include members of the patient’s family in the assessment process, if they’re available, or a close friend. If the patient does have neurologic impairment, he may have trouble remembering or remembering accurately. Family or friends can help corroborate or correct the details.

Current health status

Discover the patient’s chief complaint by asking such questions as, “What brings you to the hospital?” or “What has been bothering you lately?” Using his words, document his reasons for seeking care. If he’s suffering a neurologic disorder, you can expect reports of headaches, motor disturbances (including weakness, paresis, and paralysis), seizures, sensory deviations, or an altered level of consciousness (LOC).

Ask and you shall perceive

Encourage the patient, or a family member, to elaborate on his current condition by asking such questions as:

  • Do you have headaches? If so, how often? What triggers or causes them to occur?
  • Do you feel dizzy from time to time? If so, how often and what seems to trigger the episodes?
  • Do you ever feel a tingling or prickling sensation or numbness? If so, where?
  • Have you ever had seizures or tremors? How about weakness or paralysis in your arms or legs?
  • Do you have trouble urinating? Walking?
  • How’s your memory and ability to concentrate?
  • Have you ever had trouble speaking or understanding others?
  • Do you have trouble reading or writing?

Previous health status

Many chronic diseases can affect the neurologic system, so ask the patient what medications, if any, he’s taking as well as questions about his past health. Specifically, ask if he has had any:

  • major illnesses
  • recurrent minor illnesses
  • accidents or injuries
  • surgical procedures
  • allergies

Family health status

Information about the patient’s family may reveal a hereditary disorder. Ask if anyone in his family has had diabetes, cardiac or renal disease, high blood pressure, cancer, a bleeding disorder, a mental disorder, or a stroke.

Lifestyle patterns

The patient’s cultural and social background will affect decisions about his care, so ask questions about these facets of his life. Also, note the patient’s education level, occupation, drug use, and hobbies. As you gather this information, assess the patient’s self-image as well.

Physical examination

A complete neurologic examination is so long and detailed that — as a medical-surgical nurse — you’ll probably never perform one in its entirety. Instead, you’ll rely on a brief neurologic assessment of key neurologic status indicators, including:

  • LOC
  • pupil size and response
  • verbal responsiveness
  • extremity strength and movement
  • vital signs

When baseline values are established, regular reevaluation of these indicators, called neuro checks, will reveal trends in the patient’s neurologic function and help detect the transient changes that may signal pending problems.

In more detail

If the initial assessment suggests that the patient has an existing neurologic problem, a more detailed assessment is warranted. Always examine the patient’s neurologic system in an orderly fashion. Begin with the highest levels of neurologic function and proceed to the lowest, covering these five areas:

  • mental status (cerebral function)
  • cranial nerve function
  • sensory function
  • motor function
  • reflexes

Mental status

Develop a sense of the patient’s mental status as you talk with him during the health history. Listen and watch for clues to his orientation and memory. If you have doubts about his mental status, perform a brief screening examination. (See Quick check of mental status.)

 

Stop, look, and listen

Assessing mental status involves evaluating the patient’s LOC, appearance, behavior, speech, cognitive function, and constructional ability:

  • Level of consciousness—A change in LOC is the earliest and most sensitive indicator that neurologic status has changed. The Glasgow Coma Scale is one objective way to assess the patient’s LOC. (See Using the Glasgow Coma Scale.)
  • Appearance and behavior—Note the patient’s behavior, dress, and grooming. Even subtle changes in behavior can signal the onset of chronic disease or an acute change involving the frontal lobe.
  • Speech—Listen to how well the patient expresses himself. His ability to follow instructions and cooperate with the examination will provide clues about his level of comprehension.
  • Cognitive function—Evaluate the patient’s memory, orientation, attention span, thought content, ability to perform simple calculations, capacity for abstract thought, judgment, and emotional status.
  • Constructional ability—Assess the patient’s ability to perform simple tasks and use common objects.

Cranial nerves

Cranial nerve assessment provides valuable information about the status of the CNS, particularly the brain stem.

Getting on your nerves

Due to their location, the optic, oculomotor, trochlear, and abducens nerves are more vulnerable to an increase in intracranial pressure (ICP) than other cranial nerves. For this reason, assessment and screening focuses on these four nerves. However, if the patient’s history or symptoms indicate a potential cranial nerve disorder, or a complete nervous system assessment is ordered, assess all cranial nerves.

Assessment

Conducting an assessment for possible neurologic impairment includes a thorough health history and an investigation of physical signs of impairment.

History

Begin by asking the patient what brings him to seek care at this time. Gather details about his current health, previous health, family health, and lifestyle. Also, perform a complete systems review. It’s best to include members of the patient’s family in the assessment process, if they’re available, or a close friend. If the patient does have neurologic impairment, he may have trouble remembering or remembering accurately. Family or friends can help corroborate or correct the details.

Current health status

Discover the patient’s chief complaint by asking such questions as, “What brings you to the hospital?” or “What has been bothering you lately?” Using his words, document his reasons for seeking care. If he’s suffering a neurologic disorder, you can expect reports of headaches, motor disturbances (including weakness, paresis, and paralysis), seizures, sensory deviations, or an altered level of consciousness (LOC).

Ask and you shall perceive

Encourage the patient, or a family member, to elaborate on his current condition by asking such questions as:

  • Do you have headaches? If so, how often? What triggers or causes them to occur?
  • Do you feel dizzy from time to time? If so, how often and what seems to trigger the episodes?
  • Do you ever feel a tingling or prickling sensation or numbness? If so, where?
  • Have you ever had seizures or tremors? How about weakness or paralysis in your arms or legs?
  • Do you have trouble urinating? Walking?
  • How’s your memory and ability to concentrate?
  • Have you ever had trouble speaking or understanding others?
  • Do you have trouble reading or writing?

Previous health status

Many chronic diseases can affect the neurologic system, so ask the patient what medications, if any, he’s taking as well as questions about his past health. Specifically, ask if he has had any:

  • major illnesses
  • recurrent minor illnesses
  • accidents or injuries
  • surgical procedures
  • allergies

Family health status

Information about the patient’s family may reveal a hereditary disorder. Ask if anyone in his family has had diabetes, cardiac or renal disease, high blood pressure, cancer, a bleeding disorder, a mental disorder, or a stroke.

Lifestyle patterns

The patient’s cultural and social background will affect decisions about his care, so ask questions about these facets of his life. Also, note the patient’s education level, occupation, drug use, and hobbies. As you gather this information, assess the patient’s self-image as well.

Physical examination

A complete neurologic examination is so long and detailed that — as a medical-surgical nurse — you’ll probably never perform one in its entirety. Instead, you’ll rely on a brief neurologic assessment of key neurologic status indicators, including:

  • LOC
  • pupil size and response
  • verbal responsiveness
  • extremity strength and movement
  • vital signs

When baseline values are established, regular reevaluation of these indicators, called neuro checks, will reveal trends in the patient’s neurologic function and help detect the transient changes that may signal pending problems.

In more detail

If the initial assessment suggests that the patient has an existing neurologic problem, a more detailed assessment is warranted. Always examine the patient’s neurologic system in an orderly fashion. Begin with the highest levels of neurologic function and proceed to the lowest, covering these five areas:

  • mental status (cerebral function)
  • cranial nerve function
  • sensory function
  • motor function
  • reflexes

Mental status

Develop a sense of the patient’s mental status as you talk with him during the health history. Listen and watch for clues to his orientation and memory. If you have doubts about his mental status, perform a brief screening examination. (See Quick check of mental status.)

 

Neurologic disorders

 

Stop, look, and listen

Assessing mental status involves evaluating the patient’s LOC, appearance, behavior, speech, cognitive function, and constructional ability:

  • Level of consciousness—A change in LOC is the earliest and most sensitive indicator that neurologic status has changed. The Glasgow Coma Scale is one objective way to assess the patient’s LOC. (See Using the Glasgow Coma Scale.)
  • Appearance and behavior—Note the patient’s behavior, dress, and grooming. Even subtle changes in behavior can signal the onset of chronic disease or an acute change involving the frontal lobe.
  • Speech—Listen to how well the patient expresses himself. His ability to follow instructions and cooperate with the examination will provide clues about his level of comprehension.
  • Cognitive function—Evaluate the patient’s memory, orientation, attention span, thought content, ability to perform simple calculations, capacity for abstract thought, judgment, and emotional status.
  • Constructional ability—Assess the patient’s ability to perform simple tasks and use common objects.

 

Neurologic disordersNeurologic disorders

 

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Cranial nerves

Cranial nerve assessment provides valuable information about the status of the CNS, particularly the brain stem.

Getting on your nerves

Due to their location, the optic, oculomotor, trochlear, and abducens nerves are more vulnerable to an increase in intracranial pressure (ICP) than other cranial nerves. For this reason, assessment and screening focuses on these four nerves. However, if the patient’s history or symptoms indicate a potential cranial nerve disorder, or a complete nervous system assessment is ordered, assess all cranial nerves.

Sensory function

Sensory function assessment helps reveal problems related to:

  • stimuli detection by sensory receptors
  • sensory impulse transmission to the spinal cord by afferent nerves
  • sensory impulse transmission to the brain by sensory tracts in the spinal cord.

Few and light

Focus Topic: Neurologic Disorders

Typically, screening consists of evaluating light-touch sensation in all extremities and comparing arms and legs for symmetry of sensation. Most experts also recommend evaluating the patient’s sense of pain and vibration in the hands and feet and his ability to recognize objects by touch alone, usually with both eyes closed (stereognosis). Because the sensory system becomes fatigued with repeated stimulation, complete sensory system testing in all dermatomes tends to yield unreliable results. Usually, a few screening procedures are sufficient to reveal dysfunction.

Motor function

Assessing the motor system includes inspecting the muscles and testing muscle tone and strength. Cerebellar testing is also done because the cerebellum plays a role in smooth-muscle movements, such as tics, tremors, or fasciculations.

Tone up

Focus Topic: Neurologic Disorders

Muscle tone represents muscular resistance to passive stretching. To test arm muscle tone, move the shoulder through passive range-of-motion (ROM) exercises. You should feel a slight resistance. Then let the arm drop to the patient’s side. It should fall easily.

To test muscle tone in a leg, guide the hip through passive ROM exercises; then let the leg fall to the bed. If it falls into an externally rotated position, this is an abnormal finding.

Strength and symmetry

Focus Topic: Neurologic Disorders

To perform a general examination of muscle strength, observe the patient’s gait and motor activities. To evaluate muscle strength, ask the patient to move major muscles and muscle groups against resistance. For instance, to test shoulder girdle strength, have him extend his arms with his palms up and maintain this position for 30 seconds.

If he can’t maintain this position, test further by pushing down on his outstretched arms. If he lifts both arms equally, look for pronation of the hand and downward drift of the arm on the weaker side.

Heel to toe for the cerebellum

Focus Topic: Neurologic Disorders

Cerebellar function is evaluated by testing the patient’s balance and coordination. Ask the patient to walk heel to toe, and observe his balance. Then perform Romberg’s test. (See Romberg’s test.)

 

Neurologic disorders

 

Reflexes

Reflex assessment is usually performed as part of a comprehensive neurologic assessment. It evaluates deep tendon and superficial reflexes to determine:

  • the integrity of the sensory receptor organ
  • how effective afferent nerves are in relaying sensory impulses to the spinal cord
  • how effectively the lower motor neurons transmit impulses to the muscles
  • how well the muscles respond to the motor impulses

Deep or superficial?

Focus Topic: Neurologic Disorders

Deep tendon reflexes (muscle-stretch reflexes) occur when deep muscles stretch in response to a sudden stimulus. Superficial reflexes (cutaneous reflexes) can be elicited by light, rapid tactile stimulation, such as stroking or scratching the skin. Sometimes called primitive reflexes, pathologic superficial reflexes usually occur in early infancy and then disappear as time passes. When present in adults, they usually indicate an underlying neurologic disease.

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