Neurological System: Anatomy and Physiology
After you have successfully completed this chapter should be able to:
■ Identify pertinent sensory-neurologic system history questions
■ Obtain a sensory-neurologic system history
■ Perform a physical assessment of the sensory-neurologic
■ Document sensory-neurologic system findings
■ Identify actual/potential health problems stated as nursing diagnoses
■ Differentiate between normal and abnormal findings
The human nervous system is a unique system that allows the body to interact with the environment as well as to maintain the activities of internal organs. It is composed of structures that transmit electrical and chemical signals between the body’s systems and the brain. The multiple functions of the nervous system are so automatic that most people are unaware of their magnitude until a problem occurs. An impaired nervous system can manifest in many ways, from subtle weakness to drastic loss of mobility. The nervous system acts as the main “circuit board” for every body system.Because the nervous system works so closely with every other system, a problem within another system or within the nervous system itself can cause the nervous system to “short-circuit.” A major goal of nursing is early detection to prevent or slow the progression of disease. So it is important for nurses to accurately perform a thorough neurologic assessment and to understand the implications of subtle changes in assessment findings. By doing so, you can initiate timely interventions that can save lives. Because of the complexity of this system, assessment can be challenging, especially for beginning nurses. All body organs and most tissues are innervated; therefore, neurologic activity affects functioning within all body systems. For example, the nervous system responds to stress by increasing the heart rate, resulting in increased blood pressure (BP), whereas it responds to the sight or smell of food by increasing the production of digestive juices. Furthermore, a seemingly straightforward neurologic symptom such as headache, insomnia, or forgetfulness can have a wide range of causes, contributing factors, and consequences. Another assessment challenge may be interacting with the patient. Neurologic impairment can reduce the ability to communicate, cause confusion, alter personality, and otherwise confound your attempts to obtain an accurate health history. Finally, factors such as drug and alcohol use, medication interactions, diet, amount of sleep, and other self-care factors can influence neurologic health. Therefore, careful sleuthing is required when taking the health history and gathering and evaluating the physical findings. The previous chapter discussed neuromuscular function, just one aspect of the highly complex neurologic system.This chapter presents the sensory-neurologic assessment, including information on assessing cerebral function, cranial nerves (CNs), sensation, and reflexes. Throughout the assessment, you will identify risk factors for neurologic impairment and health promotion teaching needs. Remember to document all findings, including normal data, precisely and thoroughly, to provide a baseline against which future neurologic function can be measured. These baseline data are critically important for evaluating degeneration in patients with progressive neurologic disease, as well as for evaluating patients’ progress toward rehabilitation after neurologic trauma and other acute problems.
Anatomy and Physiology Review
Before beginning the neurologic assessment, you need to understand the anatomy and physiology of the system, including its anatomic and functional divisions and the type and extent of its interaction with other body systems. In addition to the motor aspects discussed in Chapter 20, general functions of the neurologic system include:
■ Cognition, emotion, and memory.
■ Sensation, perception, and the integration of sensoryperceptual experience.
■ Regulation of homeostasis, consciousness, temperature, BP, and other bodily processes.
Structures and Functions of the Sensory-Neurologic System
There are two types of nerve cells:neuroglia and neurons.
Neuroglia act as supportive tissue, nourishing and protecting the neurons. They also maintain homeostasis in the interstitial fluid around the neurons and account for about 50 percent of the central nervous system (CNS) volume. Neuroglia have the ability to regenerate and respond to injury by filling spaces left by damaged neurons.
Neurons have the ability to produce action potentials or impulses (excitability or irritability) and to transmit impulses (conductivity).They are composed of a cell body, dendrites, and axons.
The cell body contains the nucleus. Dendrites are short, branchlike structures that receive and carry impulses to the cell body. Axons are long fibers that carry the electrical impulses generated by the cell bodies.Some axons are covered with a myelin sheath that allows rapid impulse transmission. For neurons to communicate with one another, the axon of one neuron has to convey its impulse to the dendrite of the next neuron across a space called a synapse. It does this with the help of neurotransmitters, chemicals released by the axon that carry the impulse to the receiving dendrite. The impulses conveyed by neurons include sensory data about what the body is seeing, hearing, feeling, and so on, as well as motor data telling the muscles how to respond. Sensory impulses are transmitted to the brain through afferent, or ascending,pathways.Motor impulses are transmitted from the brain to muscles through the efferent, or descending, pathways (Fig. 21.1). Neurons band together into peripheral nerves,spinal nerves, the spinal cord, and the tissues of the brain.These structures make up the neurologic system,which is divided into the CNS and the peripheral nervous system (PNS).
The Central Nervous System
The CNS consists of the brain and spinal cord.
The brain is composed of gray matter, made up of neuronal cell bodies, and white matter, composed of axons and dendrites.The brain consists of four major structures: the cerebrum, diencephalon, cerebellum, and brainstem. These and other components of the brain are shown in Figure 21.2 and described in Structures and Functions of the Brain.
The Spinal Cord
The spinal cord descends through the foramen magnum (large aperture) of the occipital bone of the skull, through the first cervical vertebra (C1), and through the remainder of the vertebral column to the first or second lumbar vertebra. At this point, the cord itself terminates and its roots branch off into the cauda equina (“horse’s tail”). A cross-section of the spinal cord reveals gray matter composed of neuronal cell bodies clustered into an “H” shape, with two anterior and two posterior “horns.” This gray matter is surrounded by white matter composed of myelinated axons and dendrites. Cord fibers associate into ascending tracts, which carry sensory data to the brain, and descending tracts, which carry motor impulses from the brain.
Sensory pathways,either ascending or afferent,allow sensory data, such as the feeling of a burned hand, to become conscious perceptions.The pathways by which a variety of somatic sensations travel to the cerebral cortex are illustrated in Figure 21.3.The two major sensory pathways are the lateral and anterior spinothalamic tracts and the posterior column. The lateral and anterior spinothalamic tracts
transmit nerve impulses for pain, temperature, itching, tickling, pressure, and crude touch, whereas the posterior column transmits nerve impulses for proprioception, discriminative sensations, and vibrations. Some visceral sensory neurons also enter the spinal cord as shown in the figure; however, other visceral stimuli are carried by the vagus nerve or another of the cranial nerves and enter the brainstem directly, bypassing the spinal cord. All somatic sensory stimuli—for example, sensations of pain, heat, or pressure—are conveyed from the body periphery into the spinal cord via the posterior root of the appropriate spinal nerve. At that point, sensations of fine touch, proprioception, and vibration continue into the posterior column of the spinal cord and into the brainstem. Here they cross to the opposite side of the brainstem before they continue into the thalamus and from there to the sensory areas of the cerebral cortex.
In contrast to this, sensations of pain, temperature, crude touch, and pressure enter the posterior horn and cross the spinal cord into the opposite side of the cord before they begin their ascent. Pain and temperature are carried in the lateral spinothalamic tract, whereas crude touch and pressure are carried in the anterior spinothalamic tract. These tracts continue to ascend straight upward, entering the thalamus and then the cerebral cortex. As you might imagine,a patient with a particular type of sensory loss may have a neurologic impairment affecting a particular column or tract. For example, someone who loses the ability to perceive vibration and changes in positioning may have a lesion in the posterior column.
Motor pathways (descending or efferent) transmit impulses from the brain to the muscles. The three major motor pathways of the CNS are the corticospinal (pyramidal or direct), including the corticobulbar; the extrapyramidal or indirect; and the cerebellum.The descending pathways can be direct or indirect.
Direct (pyramidal) pathways carry impulses from the cerebral cortex to lower motor neurons that innervate the skeletal muscles, resulting in voluntary movement. The direct pathways include the anterior and lateral corticospinal and corticobulbar tracts. The corticospinal tracts control voluntary skilled movement of the extremities and fine movement of the fingers.The corticobulbar tract connects the motor cortex to lower motor neurons of the cranial nerves.
The indirect (extrapyramidal) pathways carry impulses from the brainstem and other parts of the brain, resulting in automatic movement,coordination of movement, and maintenance of skeletal muscle tone and posture. The indirect pathways consist of the reticulospinal, rubrospinal, tectospinal, and vestibulospinal tracts.The possible pathways of the corticospinal system are shown in Figure 21.4. The cerebellar system, which is involved primarily in coordination, equilibrium, and posture, is not shown.Also note that this discussion pertains to somatic,not visceral,motor neurons. From the motor cortex, all somatic motor impulses descend via one of three tracts through the thalamus and into the brainstem, at which point the configuration of the three tracts resembles a pyramid.The anterior corticospinal and corticobulbar (uncrossed pyramidal tract) .And the reticulospinal and vestibulospinal (uncrossed extrapyramidal tract) continue straight down into the spinal cord. There, the impulse must cross over to the opposite anterior horn before it can exit the spinal cord via the anterior root of the spinal nerve.The lateral corticospinal (crossed pyramidal tract) and the rubrospinal (crossed extrapyramidal tract) both cross to the opposite side of the brainstem before descending directly into the anterior horn and exiting into the anterior root of the spinal nerve. Motor impulses from the motor cortex to the periphery are controlled by upper and lower motor neurons. The upper motor neurons are located in the cerebral cortex and brainstem and regulate the responses of the lower motor neurons.The lower motor neuron cell bodies lie in the anterior horn of the spinal cord, then exit the cord through the nerve roots.The lower motor neurons are the final link between the CNS and the skeletal muscles. An upper motor neuron lesion causes increased muscle tone (spasticity) and hyperreflexia. A lower motor neuron lesion causes decreased tone, flaccidity, and absent reflexes or hyporeflexia.
Spinal reflexes do not depend on conscious perception and interpretation of stimuli, nor on deliberate action; in other words, they do not involve the brain. They occur involuntarily, with lightning speed, and are identical in all healthy children and adults, although they are less developed in infants.When we experience a spinal reflex, we are not aware of the reflexive activity itself, only its result. The simplest spinal reflexes are known as deep tendon reflexes (DTRs). They are monosynaptic, involving just one sensory neuron communicating across a single synapse to one responding motor neuron. A reflex arc is shown in Figure 21.5.
The classic example of a DTR is the patellar reflex, commonly called the knee-jerk reflex. The patellar reflex is an example of a stretch reflex. The patellar tendon is tapped with a reflex hammer, triggering a stretch response in the sensory fibers of the quadriceps femoris muscle. This stimulus is received by a sensory neuron,which carries it to the anterior horn of the spinal cord, where it is conveyed across a synapse to a motor neuron that then causes the muscle to contract.
Because of the simplicity of the reflex arc, this contraction occurs within less than 1 second after the hammer tap. Slow or absent DTRs could indicate a health problem affecting the peripheral nerves, such as a degeneration of their myelin sheaths. Spinal cord trauma or lesions also commonly affect reflexes; therefore, it is helpful to know the specific spinal cord segment associated with each specific reflex.The box entitled Spinal Reflexes identifies the five DTRs, as well as superficial reflexes involving stimulation of the skin, along with the segmental level at which they occur.Assessment of these reflexes is discussed later in the chapter. In addition to the monosynaptic reflexes, the body exhibits protective flexor (or withdrawal) reflexes, which help minimize trauma from harmful stimuli. For example, these reflexes allow speedy, involuntary withdrawal from a heat source. Flexor reflexes require a sensory neuron to interact with an intermediate neuron or interneuron in the spinal cord.This interneuron, in turn, sends the impulse across a synapse to the receiving motor neuron.
Peripheral Nervous System
The peripheral nervous system consists of the cranial and spinal nerves and the peripheral autonomic nervous system.The PNS can also be divided into the somatic and the visceral nervous systems.The somatic system has both afferent and efferent divisions. The afferent division receives, processes, and transmits sensory information from the skin and the musculoskeletal system,eyes,tongue, nose, and ears.The efferent division has lower motor neurons and regulates voluntary muscle contraction. The visceral system also has afferent and efferent divisions.The afferent division is responsible for processing information from the visceral organs.The efferent division is responsible for the motor responses of the smooth muscle, cardiac muscle, skin glands, and viscera.The efferent system is known as the autonomic nervous system.
The 12 pairs of cranial nerves originate from the brain and are called the peripheral nerves of the brain. As shown in Figure 21.6, these nerves originate from the cerebrum, diencephalon, and brainstem.The function of each of the cranial nerves is indicated in Function of Cranial Nerves.
Spinal and Peripheral Nerves
Branching from the spinal cord are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal (Fig. 21.7). The spinal nerves contain both ascending and descending fibers, and although there is some overlap,each is responsible for innervation of a particular area of the body. As shown in Figure 21.8, dermatomes are regions of the body innervated by the cutaneous branch of a single spinal nerve. For example, nerve C6 innervates a portion of the lateral (thumb) side of the arm and hand. Although there is some individual variation, it is useful to know which spinal nerves typically innervate which segments of the body so that neurologic deficits can be more easily associated with lesions of particular nerves. Each spinal nerve emerges from the spinal cord from two distinct roots. The posterior (dorsal) root contains afferent fibers that receive sensory information from the body periphery and convey it to the CNS.
The anterior (ventral) root contains efferent fibbers that convey motor impulses from the CNS to the muscles of the body, directing and refining movement. These anterior and posterior roots then merge just distal to the cord to form one mixed spinal nerve capable of both sensory and motor functioning. Spinal nerves branch further to form the peripheral nerves of the body, most of which also carry both sensory and motor fibers. The autonomic nervous system is divided into the sympathetic and parasympathetic, with efferent fibers to muscle, organs, or glands. Usually, the two systems work opposite each other.The sympathetic allows the body to respond to stressful situations.
The parasympathetic functions when all is normal. The sympathetic nerves exit the spinal cord between the level of the first thoracic and the second lumbar vertebrae.The preganglionic nerves descend the cord and exit, and then enter a relay station known as the sympathetic chain. The impulse is then transmitted to a postganglionic neuron that goes to the target organ to stimulate a response. Sympathetic responses include vasoconstriction; increased BP, heart rate, and contractility; increased respiratory rate; smooth muscle relaxation of bronchioles, gastrointestinal (GI) tract, and urinary tract; sphincter contraction; pupillary dilation; increased sweat, and decreased pancreatic secretion. The parasympathetic fibers leave the CNS by way of the cranial nerves from the midbrain and medulla, and between the second and the fourth sacral vertebrae. A long preganglion fiber exits to an area near the target organ, and then synapses to form a postganglionic nerve, which in turn leads to a response. Parasympathetic responses include decreased heart rate, contractility, and velocity; smooth muscle constriction of bronchioles; increased GI tract tone and peristalsis with sphincter relaxation; urinary sphincter relaxation and increased bladder tone; vasodilation of external genitalia causing male erection; pupillary constriction, and increased pancreatic, lacrimal, and salivary secretions. There is little effect on mental and metabolic activity. Figure 21.9 illustrates the autonomic nervous system
. Interaction With Other Body Systems
Because the nervous system is the main circuit board for the body, all body systems interact with it in some way.
The Cardiovascular System
Although the conduction system of the heart is completely independent of extrinsic neural control, cardiac centers in the medulla influence heart rate. Also, the vagus nerve can exert significant influence over both heart rate and vessel constriction,thereby influencing BP.
The Respiratory System
Respiratory centers in the medulla of the brainstem regulate inspiration and expiration. Centers in the pons regulate respiratory drive. The vagus nerve relays data on blood gas levels to the medulla.Voluntary regulation of breathing can be achieved via motor neurons,which can stimulate the respiratory muscles
. The Endocrine System
The secretion of some endocrine glands, such as the adrenal glands, is regulated by nerves. Some neurons in the hypothalamus actually act as endocrine cells, secreting antidiuretic hormone, which stimulates the kidneys to reabsorb water and oxytocin, a reproductive hormone. Some other hormones, notably parathyroid hormone, affect metabolism of electrolytes, which in turn affects neurologic function.
The Musculoskeletal System
Somatic and visceral motor neurons receive impulses from the cerebral cortex to carry out both voluntary and reflexive movements.
Performing the Sensory-Neurologic and Cranial Nerve Assessment
A complete assessment of the patient’s neurologic system requires you to take a detailed health history, perform a mental status examination, assess the cranial nerves, assess the sensory system, and test deep tendon and superficial reflexes.
Before you begin the health history, keep in mind that the patient may be experiencing confusion, impaired verbal communication, memory loss, personality changes, or other deficits.This may affect her or his ability to provide reliable information, so verifying subjective data with a family member or friend may be wise.
Rather than asking a long series of questions, it may be best to encourage the patient to tell her or his story without interruption.You can learn a great deal from the content of the story and also by listening to the way it is told. If time is an issue and you are unable to perform a complete health history, perform a focused history on the sensory-neurologic system.
As always, review the patient’s biographical data for clues that relate
to the neurologic system. Obviously, the patient’s age and educational level
will influence the questions you ask and the type and extent of teaching you
provide. Keep in mind that certain neurologic disorders are age related.For
example, the incidence of stroke increases with age,and neurologic diseases
such as myasthenia gravis (MG) and multiple sclerosis (MS) usually attack young
women with a peak age between 20 and 30 years. Spinal cord injuries occur more
frequently in young people because of the higher rate of accidents. Also, some
neurologic disorders are gender related. For example,women have a higher
incidence of hemorrhagic stroke, whereas men have more thrombic strokes; before
age 40, MG occurs in women two to three times more often than in men; and the
incidence of MS is higher in women than in men. Even geographical locale influ influences some types of neurologic
diseases.For instance,MS occurs most often in colder climates such as the
Current Health Status
The current health status focuses on the patient’s chief complaint. If she or he has a neurologic problem, begin with the chief complaint. Major neurologic symptoms to watch for are headache, memory loss, confusion, dizziness, loss of consciousness, numbness, sensory loss, and problems with any of the five senses. Explore these complaints using the PQRST format.
Symptom analysis tables for all the symptoms described in the following paragraphs are available for viewing and printing on the compact disc that came with the book.
Headache is the most common neurologic symptom.The causes are many.The pain may be mild or severe, acute or chronic, localized or generalized. Ninety percent of all headaches are benign in nature, caused by muscle contraction (tension) and/or vascular (migraine and cluster); the other 10 percent have underlying pathology.Because a headache may be a symptom of a serious medical problem, a careful, thorough symptom analysis is needed to determine the cause. Mental Status Changes
Mental status changes are an early indication of a change in neurologic status. The changes may be very subtle and difficult to detect.They may begin slowly as forgetfulness, memory loss, or inability to concentrate, or rapidly proceed to unconsciousness. Causes include neurologic problems, fluid and electrolyte imbalance, hypoxia, low perfusion states, nutritional deficiencies, infections, renal and liver disease, hyper- or hypothermia, trauma, medications, and drug and alcohol abuse. If your patient’s mental status is severely impaired, ask family members to describe the changes that have occurred.
Dizziness, Vertigo, and Syncope
Dizziness, vertigo, and syncope are common neurologic signs and symptoms that warrant further investigation. Dizziness is a “fainting” sensation, whereas vertigo is a sensation that the surroundings are spinning around (objective vertigo) or that the person is spinning around (subjective vertigo).Vertigo is often accompanied by nausea and vomiting, nystagmus, and tinnitus. Dizziness can lead to syncope,which is a temporary loss of consciousness. The patient may say that he or she “blacked out” or “had a spell.” Although the underlying cause of these signs and symptoms may be benign, they may also indicate a serious problem, such as an impending stroke, and need to be investigated thoroughly. Numbness or Loss of Sensation
Numbness or tingling is referred to as paresthesia. Possible causes include diabetes and neurologic, metabolic, cardiovascular, renal, and inflammatory diseases. Determine the area affected and the onset and progression of symptoms.
Deficits in the Five Senses
Assess changes in any of the five senses. Intact cranial nerves are essential for many of the senses. CN I (olfactory) is responsible for the sense of smell; CN II (optic), III (oculomotor), IV (trochlear), and VI (abducens) are responsible for visual acuity, pupillary constriction, and extraocular movement (EOM); CN VII (facial) and IX (glossopharyngeal) control taste; CN VIII (acoustic) controls hearing; and CN V (trigeminal) and dermatomes control somatic sensations. Visual problems are a frequent symptom associated with neurologic disorders and should be further assessed. Visual changes can result from ocular, neurologic, or systemic problems, eye or head trauma, or adverse effects from drugs.The anatomic position of the cranial nerves that control the eye makes the nerves vulnerable to increases in intracranial pressure (ICP). These visual changes can be total loss of vision, visual field cuts,blurred vision, diplopia (double vision), photosensitivity, and amaurosis fugax (unilateral vision loss, as if a shade were being pulled down, resulting from insufficient blood supply to the retina and lasting up to 10 minutes). The visual deficit may have an acute or gradual onset and be permanent or temporary.
Past Health History
The purpose of the past medical history is to compare it with the patient’s present neurologic status or uncover risk factors that might predispose the patient to neurologic disorders. The following questions will guide you in exploring specific areas related to the sensory-neurologic system.
The family history identifies any predisposing or causative factors for neurologic problems.
Review of Systems
The review of systems (ROS) allows you to assess how the neurologic system affects or is affected by every other system. Often, you may uncover an important fact that your patient failed to mention earlier.
The psychosocial profile reveals patterns in the patient’s life that may affect the neurologic system and put her or him at risk for neurologic disorders. It may also identify teaching needs.
Once you have obtained the subjective data, focus on collecting the objective data by performing the physical examination.
The components of the neurologic examination include tests of the patient’s:
■ Mental status.
■ Cranial nerve function.
■ Sensory function.
■ Reflex function.
As a nurse, you will perform an abbreviated screening neurologic examination more often than the comprehensive neurologic examination described here.
Although it is briefer, the screening examination still addresses each area of the neurologic assessment and includes:
■ Evaluation of loss of consciousness (LOC) with brief mental status examination and evaluation of verbal responsiveness.
■ Testing of selected cranial nerves (usually CNs II, III,IV, and VI)
. ■ Motor screening,including strength,movement,and gait (see Chapter 20,Assessing the Musculoskeletal System).
■ Sensory screening, including tactile and pain sensations on upper and lower extremities
. ■ Reflexes.
If the patient’s condition warrants it, continue to assess neurologic status by performing rapid, repeated checks to evaluate LOC, pupil size and reaction, responsiveness, extremity strength and movement,and vital signs.
The neurologic physical assessment sequence is different from that for other body systems, but you still use inspection, palpation, and auscultation. The main difference is that this examination consists of a series of tests. Even though the physical assessment establishes the objective database,many of the findings are still somewhat subjective, based on the patient’s perception. Because the exam is lengthy, make sure that the patient is seated comfortably, preferably in a chair with back support rather than on an examination table.Check from time to time to be sure that he or she is not becoming fatigued. The patient with a neurologic disorder may find it difficult to understand instructions and participate fully in the exam. In these cases, limit tests that require a lengthy explanation and active cooperation.If the patient is lethargic or exhibits any other possible alteration in LOC,then it is critical to perform an assessment for LOC. When assessing older adults, keep in mind that their responses to questions and directions may be slower and that you may need to adjust the pace of the examination. Because of the normal changes of aging and the possibility of paresis, stay close to patients to prevent them from falling, and help with position changes.
Performing a General Survey
Before you begin the specific neurologic assessment, perform a general survey, including scanning your patient from head to toe and taking vital signs. Look at every system as it relates to the neurologic system.If you detect any changes, investigate further as you perform the specific neurologic examination. The general survey can provide immediate and important information about the patient’s neurologicneurologic status.Affect, hygiene, grooming, speech, posture, and body language can provide clues to your patient’s general level of functioning, as well as any pain or impairment.Ask yourself:
■ Does the patient appear her or his stated age?
■ Is her or his affect or mood appropriate for the situation?
■ Are her or his responses appropriate?
■ Is she or he following the interview?
■ Is she or he well groomed and neatly dressed?
■ Are her or his clothes stained with food?
■ Is a female patient’s make-up appropriately applied?
Scan for symmetry, especially in the face.Ask your patient to smile, and look for symmetry of facial features. Are there any abnormal movements? Shake your patient’s hand and note muscle strength. Look at facial expression and eye contact. Is his or her speech clear or slurred? Are responses slow and deliberate or one-word? Poor grooming, food on clothing, or inappropriate make-up can reflect visual deficits such as visual field cuts; motor deficits, such as weakness or paralysis; impaired cerebral function, such as confusion; and affective problems such as depression. Poor posture or facial asymmetry (ptosis or droopy smile) may be a sign of weakness or hemiparesis. Abnormal movements or balance and coordination problems may indicate a cerebellar dysfunction.Weak hand grip may reflect weakness of a neurologic nature. Inappropriate responses, short attention span, or poor eye contact may indicate an underlying cerebral function disorder or a psychiatric problem.
Because the neurologic system plays a vital role in the regulation of vital signs, a change in vital signs can reflect a change in the neurologic system.
■ BP: HTN is a risk factor for stroke. A widened pulse pressure is a Cushing’s sign of increased ICP.
■ Pulse: Bradycardia is a Cushing’s sign indicating increased ICP; atrial fibrillation increases the risk for stroke.
■ Respirations: Irregular breathing patterns with periods of apnea are a Cushing’s sign of increased ICP.
■ Temperature: A temperature elevation may be associated with infection, meningitis, or brain abscess.A slight temperature elevation may occur after a stroke as a result of the inflammatory response, and a high temperature can occur as a result of a brainstem stroke.
Performing a Head-to-Toe Physical Assessment
The neurologic system affects the functioning of all other body systems. Therefore, it is essential to examine the patient from head to toe to note any unusual findings. Although not every abnormality you note will be related to neurologic dysfunction, you should consider a variety of possibilities.For example,a bruise on the forehead may be caused by an injury sustained when a patient with a preexisting neurologic impairment experienced an LOC. On the other hand, the patient may have been healthy before the injury, and the injury may be causing the current symptoms of pain and disorientation.
Performing a Neurologic Assessment
Once you have completed the head-to-toe scan,zero in of the specifics of the sensory-neurologic examination. Begin by assessing cerebral function, and then assess cranial nerve function, sensory function, and reflexes. The motor-musculoskeletal system was assessed in the previous chapter.
Assessment of cerebral function includes LOC, mental status and cognitive functioning, and communication. (See Assessing Cerebral Function.)
Level of Consciousness
Evaluating LOC involves assessing arousal (wakefulness) and orientation (ability to receive and accurately interpret sensory stimuli).
Determine the arousal state first, using minimal stimuli and increasing intensity as needed. Start with auditory stimuli,move to tactile stimuli, and then use painful stimuli as a last resort
. Auditory and Tactile Stimuli.
To assess auditory stimuli, determine whether the patient is sleeping or awake. If the patient is awake, what is she or he doing?
If the patient is sleeping, call her or him by name in a normaltone of voice. If she or he does not respond, speak louder.If auditory stimuli fail, try tactile. Gently touch thepatient’s hand. If she or he does not respond, gentlyshake her or his shoulder.
Painful Stimuli. If your patient does not respond to tactilestimuli, you will have to resort to painful stimuli.There are acceptable and unacceptable ways to elicit aresponse to pain. Never perform a nipple twist. Avoidusing a pin or needle, because if the skin breaks, you riskinfection.Also remember to rotate sites—repeated stimulationat the same site may cause bruising.Painful stimuli may be central or peripheral.Centralpainful stimuli include the trapezius squeeze, the sternalrub, supraorbital pressure, and mandibular pressure.Peripheral painful stimuli include nail pressure and theAchilles tendon squeeze.Apply the stimulus for 15 to 30seconds.
A responsive patient will experience pain andmove in response to these stimuli
squeeze: Pinch 1 to
■ Sternal rub: With the knuckles or the palm of yourdominant hand, apply pressure in a grinding motion tothe sternum. Do not use this site repeatedly because itwill cause bruising.
■ Supraorbital pressure: Apply firm pressure with yourthumbs at the notch at the center of the orbital rimbelow the eyebrows. Because a nerve runs in thenotch, pressure to this area will cause sinus pain. Usethis stimulus carefully to avoid damage to the eyes.
■ Mandibular pressure:With your index and middle finger,apply inward and upward pressure at the angle ofthe jaw
.■ Nail pressure: Apply pressure over the moon of thenail with a pen or pencil.
■ Achilles tendon squeeze: Squeeze the Achilles tendonbetween your thumb and your index finger.
When documenting your findings, record how yourpatient responds rather than simply giving the responsea label. For example, charting that a patient respondsslowly to verbal stimuli but drifts back to sleep is muchmore descriptive than simply writing “lethargic.”Becausea change in LOC is an early sign of a neurologic problem,you need to be able to detect subtle changes in yourpatient. Describing the response to the stimuli is moreobjective and allows better comparisons during followupassessments.The Glasgow Coma Scale (GCS) provides a moreobjective way to assess the patient’s LOC. It evaluatesbest eye response, best motor response, and best verbalresponse on a scale of 3 to 15. Fifteen (highest score)indicates that the patient is awake, alert, oriented, andable to follow simple commands. Three (lowest score) indicates that the patient does not respond to any stimulusand has no motor or eye response, reflecting a veryserious neurologic state with poor prognosis. (SeeGlasgow Coma Scale.)
Next, test orientation to time,place, and person. Purposeis also sometimes included as a fourth area of orientation.Avoid asking questions that require only a “yes” or “no”response. Start with specifics; then be more general, ifnecessary.For example,if your patient does not know thespecific date, ask him or her what month it is,and if he orshe does not know the month, ask what season it is. If heor she was once oriented to place and is not the nexttime you ask, this may be an early sign of a deterioratingneurologic status.
Ask the patient to state the date, including the yearand day of the week. Hospitalized patients—especiallyolder adults—can easily become disoriented to time, butthey usually reorient easily. Be sure your documentationreflects this.
Ask your patient to state where he or she is.Can heor she identify environmental cues (e.g., bed, equipment,sound of bells or buzzers) to determine location? A personwho is usually oriented but becomes confused when hospitalizedoften temporarily mistakes the hospital room forhome. You will need to address safety concerns withpatients who are disoriented both at home and in the hospital;for example, those with Alzheimer’s disease, whotend to wander.
Person. Ask the patient to state her or his name.Self-identityusually remains intact the longest, making disorientationto person an ominous sign.
Mental Status and Cognitive Function
Once you have determined that your patient is arousableand oriented, assess level of awareness.Level of awarenessreflects mental status and cognitive function.It is the functionalstate of the mind as judged by a person’s behavior,appearance, response to stimuli, speech, memory, andjudgment. It reflects the person’s connection with his orher environment.These areas are at a higher level of functioningthan LOC and reflect the cerebral cortex’s abilityto process and respond. Be sure to explain to your patientthat you need to ask questions that have obvious answersto accurately assess his or her neurologic status.Like the general survey, a mental status screening isoften integrated into the health history interview.A typicalscreening consists of 10 questions that address eacharea of the detailed mental status examination. Anotherinstrument that can be used to assess cognitive functionis the Mini-Mental State Examination (MMSE) (Folstein, 1975). It is used to screen for and monitor dementia.
Youwill need to perform a rigorous mental status examinationin the following situations:
■ If data from patient or patient behavior during thehealth history interview suggests an abnormality.
■ If family members or caregivers report changes in thepatient’s personality or behavior.
■ If the patient has a history of head injury, stroke, dysphasiaor aphasia, or mental illness.A mental status and cognitive function assessmentincludes: memory, general knowledge and vocabulary,mathematical and calculative skills, and thought process/abstract reasoning/judgment.
Assess immediate, recent, and remote memory. Testimmediate memory by asking your patient to repeat aseries of numbers.Test recent memory by asking whatthe patient had for breakfast or by asking her or him toname three objects—for example, a pen, a tree, and aball—and then asking her or him to recall them later.Totest remote memory, ask birth dates or anniversary datesif someone can validate the information; if not, ask datesof major historical events.
General Knowledge and Vocabulary
Before you assess general knowledge and vocabulary,youneed to consider the developmental level, educationallevel, and cultural background of your patient so that youcan phrase and direct your questions accordingly.To testgeneral knowledge,ask about current events,the name ofthe president of the United States, or common knowledgequestions, such as the number of months in a yearor days in a week.To test vocabulary, ask the patient todefine words. Begin with easy, familiar words, such as“orange,”and proceed to more difficult or abstract words,such as “dictatorial.”
Mathematical and Calculative Skills
To test mathematical and calculative skills, have yourpatient solve a simple math problem.Counting backwardfrom 100 by 7s (serial 7s) is frequently used, but this isdifficult for many people, especially those dependent oncalculators.As an alternative,have the person count backwardby 3s or 4s,or ask him or her to solve a simple problem.An example is: “If you purchased a magazine for$1.50, and you have $2.00,how much change would youget back?”Whichever method you use, make sure theproblem is appropriate for the patient’s educationallevel.
Thought Process/Abstract Reasoning/Judgment
To assess thought process, examine the appropriateness,organization, and content of your patient’s responsesthroughout the entire assessment. Be alert for any sensory-perceptual experiences, feelings, or false beliefs thatare not based on reality and may indicate illusions, hallucinations,or delusions.Assess abstract reasoning by asking your patient toexplain a simple proverb, such as “People in glass housesshouldn’t throw stones.” If the person’s age or culturalbackground makes using proverbs inappropriate, use aphrase such as “It’s raining cats and dogs!”Note the degreeof concreteness or abstractness of her or his interpretation.You can further assess abstract ability by asking her orhim to group similar objects; for example,ask “What do anapple,an orange,and a pear have in common?”Then determinewhether the responses are appropriate.Sound judgment involves considering options andchoosing appropriate actions. Assess your patient’s judgmentby observing his or her response to the currentsituation or by giving him or her a hypothetical situation.For example,say:“If you were walking down the street andwitnessed a car accident,what would you do?”Then decidewhether the response is appropriate and reasonable.
When assessing speech, evaluate not only the ability tospeak but also the content, appropriateness, speed, andquality of speech. Identify the patient’s primary language,and solicit an interpreter if needed.Various speech problemsare associated with neurologic disorders, and thetype of problem depends on which area of the brain isaffected. Increasing language difficulties may reflect aturn for the worse in your patient’s neurologic status thatwarrants further medical evaluation.The inability to communicatecan be frustrating for both of you,so be patient,allow your patient time to respond, and make referrals tospeech therapy as needed.To pinpoint the exact location of the neurologicproblem, assess further for spontaneous speech, soundrecognition, auditory-verbal comprehension, visualrecognition, visual-verbal comprehension,motor speech,automatic speech, naming, vocabulary,writing, and copyingfigures.This assessment can also be used to developan effective speech therapy plan for your patient.
Cranial Nerve Function
Evaluation of the cranial nerves is an essential part of theneurologic examination. However, like other portions ofthe exam, it depends upon an alert patient who is emotionally,cognitively, and physically able to participate.Assessment techniques are described in the following section.See Chapter 12, Assessing the Eye and the Ear, forassessment techniques for CNs II, III, IV,VI, and VIII. (SeeAssessing the Cranial Nerves.)
Sensory System Function
Assess the patient’s sensory function using tests of light(superficial) touch, pain, temperature, vibration, positionsense, stereognosis (ability to recognize the form ofsolid objects by touch), graphesthesia (ability to recognizeoutlines, numbers, words, or symbols written onskin), two-point discrimination, point localization, andextinction. Light touch, pain, and temperature are super-ficial sensations and travel the spinothalamic tracts of theanterolateral system.Vibration, position sense, stereognosis,graphesthesia, two-point discrimination, point localization,and extinction are highly localized and travel thedorsal column–medial lemniscal pathway of the posteriorcolumn-medial lemniscal pathway.Before beginning this portion of the examination,inform the patient that you will apply various stimuli,andthat she or he should close the eyes during the entireexam. Instruct her or him to say “now” whenever she orhe perceives a sensation.Avoid asking leading questions,such as, “Can you feel anything here?”Also avoid usingany recognizable pattern, but do test symmetricalregions. If you notice an area of altered sensation, stimulateareas close to it until you have delineated its borders.Record your findings with a diagram of the area.The extent of the sensory assessment depends onyour findings. For screening purposes, include the upperand lower extremities and the trunk. If you detect adeficit, perform a more thorough assessment.
Reflex assessment evaluates the intactness of thespinal cord. Intact sensory and motor systems arerequired for a normal reflex response. Normal reflexesinclude DTRs and superficial reflexes. There are alsoprotective reflexes that are responses of intact cranialnerves.The protective reflexes include the gag, coughand swallow, blink and corneal. CNs IX and X areresponsible for the gag, cough and swallow, and CNs Vand VII are responsible for the blink and cornealreflexes. Reflexes that normally occur in newborns aretermed pathological or primitive reflexes when theyoccur in adults.Deep Tendon and Superficial Reflexes
DTRs include the biceps (C5, C6), triceps (C7, C8), brachioradialis(C5, C6),patellar (L2, L3, L4) and Achilles (S1,S2). Superficial reflexes include the plantar (L4 to S2),abdominal (T8,T9,T10), anal (S3, S4, S5), cremasteric (L1,L2), and bulbocavernous (S3, S4).To test DTRs, use a rubber percussion hammer toswiftly tap a slightly stretched tendon to elicit contraction ofan associated skeletal muscle.Keep your wrist loose so thatimmediately upon impact, it swings back spontaneously.Aswith other neurologic assessments, test reflexes bilaterally.Then grade DTRs on a scale from 0 to 4. Stick figures areoften used to chart DTR findings (Fig. 21.10).
Because the normal response for a DTR is musclecontraction, eliciting a response may be difficult if yourpatient is tense and the muscles are contracted. Through cognitive inhibition, the patient can override and suppressthe peripheral reflex response.Tell your patient torelax and let you support the limb being tested. If you arestill having difficulty eliciting a DTR response, use a reinforcementtechnique to enhance the response. One technique,distraction maneuvers, allows the patient to concentrateon something other than the reflex being tested,thereby relaxing the area and eliminating unintentionalcognitive inhibition. The other technique, isometricmaneuvers, overrides the inhibitory message from thebrain and increases reflex response. Two isometricmaneuvers are having your patient clench his or her teeth(enhances upper extremity reflexes) and having thepatient interlock his or her hands and push (enhanceslower extremity reflexes).These techniques are shown inFigure 21.11. If you use a reinforcement technique, besure to document it.When assessing superficial reflexes, use a tongueblade, the base of the reflex hammer, or the back ofyour thumbnail and stroke the body briskly, withoutpressing into the underlying organs.
Superficial reflexesare graded as positive or negative. DTRs are gradedas follows:
■ 0: No response detected.
■ 1: Response present but diminished (hypoactive).
■ 2: Response normal.
■ 3: Response somewhat stronger than normal.
■ 4: Response hyperactive with clonus.
Grades 1 and 3 are usually considered normal.Evengrade 0 may occur symmetrically in some patients in theabsence of any underlying neurologic disorder.For example,a patellar reflex may be difficult to elicit on a patientwho has had knee surgery. Grade 4 usually indicatespathology. Clonus is the presence of rhythmic involuntarycontractions, most often at the foot and ankle.Sustained clonus confirms CNS involvement.
Pathological or Primitive Reflexes
Pathological or primitive reflexes usually indicate asevere underlying neurologic problem.They reflect cerebraldegeneration or late-stage dementia and are referredto as primitive reflexes because they are normally seenin a newborn with an immature neurologic system.Family members may be misled by these reflexes, whichmay seem like a sign of improvement.Therefore, be sureto explain that these are reflexive responses and providesupport for the family.Primitive reflexes include the following:■ Grasp: Place your fingers in palm of patient’s hand.Patient will close her or his fingers and grasp yours.
■ Sucking: Gently stimulate patient’s lips with a mouthswab. Patient will start sucking.
■ Snout: Gently tap oral area with finger. Patient’s lipswill pucker.
■ Rooting: Gently stroke side of patient’s face. Patientwill turn toward stimulated side
■ Glabellar: Gently tap on patient’s forehead.Patient willblink.
■ Babinski: Stroke lateral aspect of sole of foot. Dorsi-flexion of great toe and fanning of toes will occur.
Classic signs of meningitis include nuchal rigidity (extensionof neck with resistance to flexion), fever, photosensitivity,headache, nausea, and vomiting. If you suspectthat your patient has meningitis, assess for Kernig’s andBrudzinski’s signs.To assess for Kernig’s sign (Fig. 21.12), have thepatient lie supine with one leg flexed.Tell him or her totry to extend the leg while you apply pressure to theknee.Contraction and pain of the hamstring muscles andresistance to extension are positive signs of meningitis.To assess for Brudzinski’s sign (Fig. 21.13), have thepatient lie supine with her or his head flexed to her or hischest. Flexion of the hips is a positive sign of meningitis.
■ This chapter taught you how to perform a thoroughsensory-neurologic assessment, including a health historyand physical examination. Before you begin theassessment, you an understanding of the anatomy ofthe neurologic system is essential. Because the neurologicsystem is the main circuit board for the entirebody, a problem in the neurologic system can affect aperson’s well being and ability to function
■ Begin by taking a detailed health history looking forclues related to the neurologic system.
■ The physical examination of the neurologic system differsfrom other assessments.The exam includes assessmentof cerebral function, cranial nerve function, sensoryfunction, and reflexes.
■ After you complete your assessment,analyze your findingsto identify actual and potential health problems,as well as write nursing diagnoses and plan of care.