Nursing Assessment of Patients with Neurological Disorders
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Nursing Assessment Nervous System
LEARNING OUTCOMES
1. Differentiate between the functions of neurons and glial cells.
2. Explain the anatomic location and functions of the cerebrum, brainstem, cerebellum, spinal cord,
peripheral nerves, and cerebrospinal fluid.
3. Identify the major arteries supplying the brain.
4. Describe the functions of the 12 cranial nerves.
5. Compare the functions of the two divisions of the autonomic nervous system.
6. Link the age-related changes in the neurologic system to the differences in assessment findings.
7. Select significant subjective and objective data related to the nervous system that should be
obtained from a patient.
8. Select appropriate techniques to use in the physical assessment of the nervous system.
9. Differentiate normal from abnormal findings of a physical assessment of the nervous system.
10. Describe the purpose, significance of results, and nursing responsibilities related to diagnostic
studies of the nervous system.
STRUCTURES AND FUNCTIONS OF NERVOUS SYSTEM
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Human nervous system is responsible for the control & integration of the body’s many activities.
The nervous system is divided into the central nervous system and peripheral nervous system.
The central nervous system (CNS) consists of brain, spinal cord, & cranial nerves I & II.
The peripheral nervous system (PNS) consists of cranial nerves III to XII, spinal nerves, and the
peripheral components of the autonomic nervous system (ANS).
Cells of Nervous System
The nervous system is made up of two types of cells: neurons and glial cells.
Neurons
Neurons are the primary functional unit of the nervous system; they have many shapes & sizes.
Characteristics neurons:
1) Excitability, or the ability to generate a nerve impulse;
2) Conductivity, or the ability to transmit an impulse; and
3) Influence other neurons, muscle cells or glandular cells by transmitting nerve impulses to them.
A typical neuron consists of a cell body, multiple dendrites, and an axon (Fig. 1).
 The cell body is the metabolic center of the neuron.
 Dendrites extending from cell body that receive impulses from the axons of other neurons and
conduct impulses toward the cell body.
 The axon (cm - > meter). The axon carries nerve impulses to other neurons or to end organs.
Many axons in the CNS and PNS are covered by a myelin sheath, (white, lipid substance that acts as
an insulator for the conduction of impulses).
Axons may be myelinated (long fibers) or unmyelinated (smaller fibers).
Neurons are nonmitotic, if damaged, neurons could not be replaced.
The discovery of neuronal stem cells now demonstrates that neurogenesis occurs in adult brains
after cerebral injury.
1
FIG. 1 Structural features of neurons: dendrites, cell
body, and axons.
Glial Cells
 Glial cells (glia or neuroglia) provide support, nourishment & protection to neurons. Glial cells
constitute half of the brain & spinal cord mass and are 5-10 times more numerous than neurons.
 Glial cells are divided into microglia and macroglia.
 Microglia → macrophages → (phagocytosis) protect neurons, move within brain and multiply when
brain is damaged. Macroglial cells include → Astrocytes, Oligodendrocytes & Ependymal cells.
Astrocytes are found primarily in gray matter, they performed the following action.
 Provide structural support to neurons.
 Play a role in synaptic transmission (conduction of impulses between neurons).
 Phagocytes for neuronal debris when the brain is injured.
 They help restore neurochemical milieu
 Provide support for repair.
 Proliferation of astrocytes contributes to the formation of scar tissue (gliosis) in the CNS.
Oligodendrocytes are specialized cells that produce the myelin sheath of nerve fibers in the CNS
and are primarily found in the white matter of the CNS.
Ependymal cells line the brain ventricles and aid in the secretion of cerebrospinal fluid (CSF).
 Neuroglia are mitotic & can replicate. In general, when neurons are destroyed, the tissue is replaced
by the proliferation of neuroglial cells.
Nerve Regeneration
 Damaged nerve cells attempt to grow back by sprouting many branches from damaged ends of
their axons. Axons in CNS are less successful than peripheral axons in regeneration.
 Injured nerve fibers in PNS can regenerate by growing within the protective myelin sheath of the
supporting Schwann cells if cell body is intact.
Nerve Impulse
 The neuron initiate, receive & process messages about events both within & outside the body.
 Once an action potential is initiated, a series of action potentials travels along axon.
 When the impulse reaches the end of the nerve fiber, it is transmitted across the junction between
nerve cells (synapse) by a chemical interaction involving neurotransmitters.
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 This chemical interaction generates another set of action potentials in the next neuron. These
events are repeated until the nerve impulse reaches its destination.
 Because of its insulating capacity, myelination of nerve axons facilitates the conduction of an
action potential. Many peripheral nerve axons have nodes of Ranvier (gaps in the myelin sheath)
that allow an action potential to travel much faster by jumping from node to node without
traversing the insulated membrane segment. This is called salutatory (hopping) conduction. In an
unmyelinated fiber, the wave of depolarization travels the entire length of the axon, with each
portion of the membrane becoming depolarized in turn.
Synapse.
A synapseis the structural and functional junction between two neurons. It is the point at which the
nerve impulse is transmitted from one neuron to another. The nerve impulse can also be transmitted from
neurons to glands or muscles. The essential structures of synaptic ransmission are a presynaptic terminal, a
synaptic cleft, and a receptor site on the postsynaptic cell.
Neurotransmitters
Neurotransmitters are chemicals that affect the transmission of impulses across the synaptic
cleft. Excitatory neurotransmitters (e.g., epinephrine, norepinephrine, glutamate) activate postsynaptic
receptors that increase the chance that an action potential will be generated. Inhibitory neurotransmitters
(e.g., serotonin, γ-aminobutyric acid [GABA], dopamine) activate postsynaptic receptors to decrease the
chance that an action potential will be generated. For example, endorphins block pain transmission while
substance P makes nerves more sensitive to pain.
TABLE -1 NEUROTRANSMITTERS
Neurotransmitter
Acetylcholine
Amines
Epinephrine
(adrenalin)
Norepinephrine
Serotonin
Dopamine
Amino Acids
γ-Aminobutyric acid
(GABA)
Glutamate and aspartate
Clinical Relevance
A decrease in acetylcholine-secreting neurons
Is seen in Alzheimer’s disease. Myasthenia gravis results from a reduction in
acetylcholine receptors.
Is both a hormone and neurotransmitter. Produced in neurons of CNS and
neurosecretory cells of adrenal medulla.
Critical component of the fight-or-flight response of SNS.
Is both a hormone and neurotransmitter. Has important role as neurotransmitter
released from SNS affecting the heart.
Along with epinephrine, has important role in fight-or-flight response,
increasing heart rate, triggering the release of glucose from energy stores, and
increasing blood flow to skeletal muscle.
Primarily found in GI tract, platelets, and CNS.
Involved in moods, emotions, and sleep.
Produced in several areas of brain. Involved in emotions and moods and
regulating motor control. Parkinson’s disease results from destruction of
dopamine-secreting neurons.
Chief inhibitory neurotransmitter in CNS. Has a role in regulating neuronal
excitability throughout the nervous system. Drugs that increase GABA
function have been used to treat seizure disorders.
Plays key role in learning and memory.
Sustained release of glutamate and prolonged excitation is toxic to nerve cells.
Glutamate is a destructive factor in amyotrophic lateral sclerosis.
Neuropeptides Endorphins Endogenous opioids that function as neurotransmitters. Produced in pituitary
and enkephalins
gland and hypothalamus. Produce analgesia and a feeling of well-being.
The opioids morphine and heroin bind to endorphin and enkephalin receptors
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Substance
P
and produce the same effect as the endogenous opioids.
Neurotransmitter in pain transmission pathways. Morphine blocks its release.
Central Nervous System
Components of the CNS include cerebrum (cerebral hemispheres), brainstem, cerebellum & spinal cord.
Spinal Cord
The spinal cord is continuous with the brainstem and exits from the cranial cavity through the foramen
magnum. A cross section of the spinal cord reveals gray matter that is centrally located in an H shape and
is surrounded by white matter. The gray matter contains the cell bodies of voluntary motor neurons,
preganglionic autonomic motor neurons, and association neurons (interneurons). The white matter
contains the axons of the ascending sensory and the descending (suprasegmental) motor fibers. The spinal
pathways or tracts are named for the point of origin and the point of destination (e.g., spinocerebellar tract
[ascending], corticospinal tract [descending]).
Ascending Tracts
In general, the ascending tracts carry specific sensory information to higher levels of the CNS. This
information comes from special sensory receptors in the skin, muscles and joints, viscera, and blood
vessels and enters the spinal cord by way of the dorsal roots of the spinal nerves.
The fasciculus gracilis and fasciculus cuneatus (commonly called dorsal or posterior columns)
carry information and transmit impulses concerned with touch, deep pressure, vibration, position sense,
and kinesthesia (appreciation of movement, weight, and body parts).
The spinocerebellar tracts carry information about muscle tension and body position to cerebellum
for coordination of movement.
The spinothalamic tracts carry pain and temperature sensations.
Descending Tracts
Descending tracts carry impulses that are responsible for muscle movement. Among the most
important descending tracts are the corticobulbar & corticospinal tracts, collectively termed the pyramidal
tract, these tracts carry volitional (voluntary) impulses from cerebral cortex to cranial & peripheral
nerves. Another group of descending motor tracts carries impulses from the extrapyramidal system (all
motor systems except the pyramidal) concerned with voluntary movement. It includes pathways originating
in the brainstem, basal ganglia, and cerebellum.
Lower and Upper Motor Neurons
Lower motor neurons (LMNs) are the final common pathway through which descending motor tracts
influence skeletal muscle. The cell bodies of LMNs, which send axons to innervate the skeletal muscles of
the arms, trunk, and legs, are located in the anterior horn of the corresponding segments of the spinal cord
(e.g., cervical segments contain LMNs for the arms).
LMNs for skeletal muscles of the eyes, face, mouth, and throat are located in the corresponding
segments of the brainstem. These cell bodies and their axons make up the somatic motor components of
the cranial nerves. LMN lesions generally cause weakness or paralysis, denervation atrophy, hyporeflexia
or areflexia, and decreased muscle tone (flaccidity).
Upper motor neurons (UMNs)
Originate in the cerebral cortex and project downward. The corticobulbar tract ends in the brainstem,
and the corticospinal tract descends into the spinal cord. These neurons influence skeletal muscle movement.
UMN lesions generally cause weakness or paralysis, disuse atrophy, hyperreflexia, and increased muscle
tone (spasticity).
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Reflex Arc
A reflex is an involuntary response to stimuli. In the spinal cord, reflex arcs play an important role in
maintaining muscle tone, which is essential for body posture. The components of a monosynaptic reflex
arc (Fig. 2) are a receptor organ, an afferent neuron, an effector neuron, and an effector organ (e.g.,
skeletal muscle). The afferent neuron synapses with the efferent neuron in the gray matter of the spinal cord.
More complex reflex arcs have other neurons (interneurons) in addition to the afferent neuron influencing the
effector neuron.
FIG.-2 Basic diagram of the patellar
“knee jerk” reflex arc, including the (1)
sensory stretch receptor, (2) afferent
sensory neuron, (3)
interneuron,
(4)efferent motor neuron, and (5)
quadriceps muscle (effector organ)
Brain
The term brain usually refers to the three major intracranial components: cerebrum, brainstem, and
cerebellum.
FIG -3 Left hemisphere of cerebrum, lateral surface,
showing major lobes and areas of the brain.
Cerebrum
The cerebrum is composed of the right & left cerebral hemispheres and divided into four lobes: frontal,
temporal, parietal, and occipital (Fig.3). The functions of the cerebrum are multiple and complex (Table -2).
 The frontal lobe controls higher cognitive function, memory retention, voluntary eye movements,
voluntary motor movement, and speech in Broca's area.
 The temporal lobe integrates somatic, visual, and auditory data & contains Wernicke’s speech area.
 The parietal lobe interprets spatial information and contains the sensory cortex.
 Processing of sight takes place in the occipital lobe.
The division of the cerebrum into lobes is useful to delineate portions of the neocortex (gray matter),
which makes up the outer layer of the cerebral hemispheres.
Neurons in specific parts of the neocortex are essential for various highly complex and sophisticated
aspects of mental function, such as language, memory, and appreciation of visual-spatial relationships.
The basal ganglia, thalamus, hypothalamus, and limbic system are also located in the cerebrum.
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The basal ganglia are a group of structures located centrally in the cerebrum and midbrain.
Most of them are on both sides of the thalamus.
The function of the basal ganglia includes the initiation, execution, and completion of voluntary
movements, learning, emotional response, and automatic movements associated with skeletal muscle
activity (e.g., swinging the arms while walking, swallowing saliva, and blinking).
The thalamus (part of the diencephalon) lies directly above the brainstem (Fig.-4) and is the major
relay center for afferent inputs to the cerebral cortex.
The hypothalamus is located just inferior to the thalamus and slightly in front of the midbrain. It
regulates the ANS and the endocrine system. The limbic system is located near the inner surfaces of the
cerebral hemispheres and is concerned with emotion, aggression, feeding behavior, and sexual response.
Brainstem
The brainstem includes the midbrain, pons, and medulla (Fig. -4). Ascending and descending fibers
to and from the cerebrum and cerebellum pass through the brainstem. The nuclei of cranial nerves III
through XII are in the brainstem.
Vital centers concerned with respiratory, vasomotor & cardiac function are located in medulla.
Also located in the brainstem is the reticular formation, a diffusely arranged group of neurons and their
axons that extend from the medulla to the thalamus and hypothalamus. The functions of the reticular
formation include relaying sensory information, influencing excitatory and inhibitory control of spinal
motor neurons, and controlling vasomotor and respiratory activity.
The reticular activating system (RAS) is a complex system that requires communication among the
brainstem, reticular formation, and cerebral cortex. The RAS is responsible for regulating arousal and
sleep-wake transitions.
The brainstem also contains the centers for sneezing, coughing, hiccupping, vomiting, sucking, and
swallowing.
(Fig.4) Major divisions of the central nervous system
(CNS).
Cerebellum
The cerebellum is located in the posterior part of the cranial fossa inferior to the occipital lobe. The
cerebellum coordinates voluntary movement and maintains trunk stability and equilibrium.
The cerebellum receives information from the cerebral cortex, muscles, joints, and inner ear.
It influences motor activity through axonal connections to the motor cortex, the brainstem nuclei, and their
descending pathways.
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TABLE 2 FUNCTION OF CEREBRUM
Part
Cortical Areas
Motor
Primary
Supplemental
Sensory Somatic
Visual
Auditory
Association
areas
Location
Precentral gyrus
Anterior to precentral gyrus
Postcentral gyrus
Occipital lobe
Superior temporal gyrus
Parietal lobe
Function
Motor control and movement on opposite side of body
Facilitates proximal muscle activity, including activity for
stance and gait, and spontaneous movement and coordination
Posterior temporal lobe
Anterior temporal lobe
Anterior frontal lobe
Sensory response from opposite side of body
Registers visual images
Registers auditory input
Integrates somatic and sensory input
Integrates visual and auditory
Input for language comprehension
Integrates past experiences
Controls higher-order Processes (e.g., judgment, reasoning)
Language
Comprehension
Wernicke’s area
Integrates auditory language (understanding of spoken words)
Expression
Broca’s area
Regulates verbal expression
Basal Ganglia
Near lateral ventricles of Both
cerebral hemispheres
Control and facilitate learned and automatic movements
Thalamus
Below basal ganglia
Relays sensory and motor input to and from the cerebrum
Hypothalamus
Below thalamus
Regulates endocrine and autonomic functions
Limbic System
Lateral to hypothalamus
Influences emotional behavior and basic drives such as feeding
and sexual behavior
Ventricles and Cerebrospinal Fluid
The ventricles are four interconnected fluid-filled cavities. The lower portion of the fourth ventricle
becomes the central canal in the lower part of the brainstem. The spinal canal extends centrally through the
full length of the spinal cord.
Cerebrospinal fluid (CSF)
CSF circulates within the subarachnoid space that surrounds the brain, brainstem, and spinal cord.
This fluid provides cushioning for the brain and the spinal cord, allows fluid shifts from the cranial cavity
to the spinal cavity, and carries nutrients.
The formation of CSF in the choroid plexus in the ventricles involves both passive diffusion and
active transport of substances. CSF resembles an ultrafiltrate of blood. Although CSF is produced at an
average rate of about 500 mL/day, many factors influence CSF production and absorption.
The ventricles and central canal are normally filled with an average of 135 mL of CSF. Changes in
the rate of production or absorption will result in a change in the volume of CSF that remains in the
ventricles and central canal.
Excessive buildup of CSF results in a condition known as hydrocephalus. The CSF circulates
throughout the ventricles and seeps into the subarachnoid space surrounding the brain and spinal cord. It is
absorbed primarily through the arachnoid villi (tiny projections into the subarachnoid space), into the
intradural venous sinuses, and eventually into the venous system. The analysis of CSF composition
provides useful diagnostic information related to certain nervous system diseases. CSF pressure is often
measured in patients with actual or suspected intracranial injury.
Increased intracranial pressure, indicated by ↑ CSF pressure, can force downward (central)
herniation of the brain and brainstem.
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Peripheral Nervous System
The PNS includes all the neuronal structures outside the CNS. It consists of the spinal and cranial
nerves, their associated ganglia (groupings of cell bodies), and portions of the ANS.
Spinal Nerves
The spinal cord is series of spinal segments; each segment contains a pair of dorsal (afferent) sensory
nerve fibers or roots and ventral (efferent) motor fibers or roots, which innervate a specific region of the
body. This combined motor-sensory nerve is called a spinal nerve (Fig. 5).
The cell bodies of the voluntary motor system are located in the anterior horn of the spinal cord
gray matter. The cell bodies of the autonomic (involuntary) motor system are located in the anterolateral
portion of the spinal cord gray matter. The cell bodies of sensory fibers are located in the dorsal root
ganglia just outside the spinal cord. On exiting the spinal column, each spinal nerve divides into ventral
and dorsal rami, a collection of motor and sensory fibers that eventually goes to peripheral structures (e.g.,
skin, muscles, viscera).
A dermatome is the area of skin innervated by the sensory fibers of a single dorsal root of a spinal nerve
(Fig.6). The dermatomes give a general picture of somatic sensory innervation by spinal segments. A
myotome is a muscle group innervated by the primary motor neurons of a single ventral root. The
dermatomes and myotomes of a given spinal segment overlap with those of adjacent segments because of the
development of ascending and descending collateral branches of nerve fibers.
Fig.5 Cross section of spinal cord showing
attachments of spinal nerves and coverings of the
spinal cord.
Cranial Nerves
The cranial nerves (CNs) are the 12 paired nerves composed of cell bodies with fibers that exit from
the cranial cavity. Unlike the spinal nerves, which always have both afferent sensory and efferent motor
fibers, some CNs are only sensory, some only motor, and some both.
Table 56-3 summarizes the motor and sensory components of the CNs. Fig. 56-7 shows the position of the
CNs in relation to the brain and spinal cord. Just as the cell bodies of the spinal nerves are located in specific
segments of the spinal cord, so are the cell bodies (nuclei) of the CNs located in specific segments of the
brain. Exceptions are the nuclei of the olfactory and optic nerves. The primary cell bodies of the olfactory
nerve are located in the nasal epithelium, and those of the optic nerve are in the retina.
TABLE 56-3 CRANIAL NERVES
Nerve
Connection With Brain
Function
I Olfactory
II Optic
Anterior ventral cerebrum
Lateral geniculate body of the
thalamus
Midbrain
Sensory: from olfactory (smell)
Sensory: from retina of eyes (vision)
III Oculomotor
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Motor: to four eye movement muscles and levator
IV Trochlear
Midbrain
V Trigeminal
 Ophthalmic branch
 Maxillary branch
 Mandibular branch
Pons
Pons
Pons
VI Abducens
VII Facial
Pons
Junction of pons and medulla
VIII Vestibulocochlear
 Vestibular branch
 Cochlear branch
IX Glossopharyngeal
Junction of pons and medulla
Junction of pons and medulla
Medulla
X Vagus
Medulla
XI Accessory
Medulla &
segments
Medulla
XII Hypoglossal
superior
spinal
palpebrae muscle
Parasympathetic: smooth muscle in eyeball
Motor: to one eye movement muscle, the superior
oblique muscle
Sensory: from forehead, eye, superior nasal cavity
Sensory: from inferior nasal cavity, face, upper teeth,
mucosa of superior mouth
Sensory: from surfaces of jaw, lower teeth, mucosa of
lower mouth, and anterior tongue
Motor: to muscles of mastication
Motor: to the lateral rectus of the eye
Motor: to facial muscles of expression and cheekmuscle
Sensory: taste from anterior two thirds of tongue
Sensory: from equilibrium sensory organ, the vestibular
apparatus
Sensory: from auditory sensory organ, the cochlea
Sensory: from pharynx and posterior tongue, including
taste
Motor: to superior pharyngeal muscles
Sensory: from much of viscera of thorax
and
abdomen
Motor: to larynx and middle and inferior pharyngeal
muscles
Parasympathetic: heart, lungs, most of digestive system
Motor: to sternocleidomastoid and trapezius muscles
Motor: to muscles of tongue
TABLE 56-4 GERONTOLOGIC ASSESSMENT DIFFERENCES
Nervous System
Component
Central Nervous System
Brain
Peripheral Nervous System
Cranial and spinal nerves
Functional Divisions
Motor
Sensory*
Changes
Differences
Findings
in
Assessment
↓ Cerebral blood flow and Alterations in mental functioning.
metabolism
Impaired ability to adapt to
↓ Efficiency of temperatureenvironmental temperature.
regulating mechanism
Conduction of nerve impulses
↓ Neurotransmitters, loss of slowed, response time slowed.
neurons
Changes in gait and ambulation.
↓ O2 supply
Diminished kinesthetic sense.
Cerebral tissue atrophy and ↑ size Altered balance, vertigo, syncope.
of ventricles
↑ Postural hypotension.
Proprioception diminished.
↓
Sensory input.
Loss of myelin and ↓ conduction ↓ Reaction time in specific nerves.
time
↓ Speed and intensity of neuronal
Cellular degeneration, death of reflexes.
neurons
↓ Muscle bulk
↓ Sensory receptors
↓ Electrical activity
Atrophy of taste buds
Degeneration and loss of fibers in
olfactory bulb
Degenerative changes in nerve
9
Diminished strength and agility.
Diminished sense of touch, pain,
and temperature.
Slowing of or alteration in sensory
reception.
Signs of malnutrition, weight loss.
Diminished sense of smell.
cells in inner ear, cerebellum, and Poor ability to maintain balance,
proprioceptive pathways
widened gait.
Reflexes
↓ Deep tendon reflexes
↓ Sensory conduction velocity
Reticular Formation
Reticular activating system
Below-average reflex score.
Sluggish reflexes, slowing of
reaction time.
Modification of hypothalamic Disturbances in sleep patterns.
function, ↓ stage IV sleep
Autonomic Nervous System
Sympathetic nervous system and
parasympathetic nervous system
Morphologic features of ganglia, Orthostatic hypotension, systolic
slowing of autonomic nervous hypertension.
system responses
Autonomic Nervous System
The autonomic nervous system (ANS) is divided into the sympathetic and parasympathetic systems. The
ANS governs involuntary functions of cardiac muscle, smooth muscle, and glands through both efferent
and afferent pathways. The two systems function together to maintain a relatively balanced internal
environment. The preganglionic cell bodies of the sympathetic nervous system (SNS) are located in spinal
segments T1 through L2.
The major neurotransmitter released by the postganglionic fibers of the SNS is norepinephrine, and the
neurotransmitter released by the preganglionic fibers is acetylcholine.
The preganglionic cell bodies of the parasympathetic nervous system (PSNS) are located in the brainstem
and the sacral spinal segments (S2 through S4). Acetylcholine is the neurotransmitter released at both
preganglionic and postganglionic nerve endings.
SNS stimulation activates the mechanisms required for the “fight-or-flight” response that occurs throughout
the body. In contrast, the PSNS is geared to act in localized and discrete regions. It serves to
conserve & restore the body’s energy stores. The ANS provides dual and often reciprocal
innervation to many structures. For example, the SNS increases the rate and force of heart
contraction and the PSNS decreases the rate and force.
Cerebral Circulation
The brain’s blood supply arises from the internal carotid arteries (anterior circulation) and the
vertebral arteries (posterior circulation), which are shown in Fig.-8.
1. Internal carotid arteries provide blood flow to anterior and middle portions of cerebrum.
2. Vertebral arteries join to form basilar artery and provide blood flow to brainstem,
cerebellum, and posterior cerebrum.
3. Circle of Willisis formed by communicating arteries that join basilar & internal carotid
arteries (Fig.-9). The circle of Willis is a safety valve for regulating cerebral blood flow
when differential pressures or vascular occlusions are present.
4. Superior to circle of Willis, three pairs of arteries supply blood to the left and right
hemispheres. The anterior cerebral artery feeds the medial and anterior portions of the
frontal lobes.
5. The middle cerebral artery feeds outer portions of frontal, parietal, & superior
temporal lobes.
6. The posterior cerebral artery feeds medial portions of the occipital and inferior
temporal lobes. Venous blood drains from the brain through the dural sinuses, which
form channels that drain into the two jugular veins.
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FIG.6 The cranial nerves are numbered according to the FIG.7 Dermatomes of the body.
order in which they leave the brain
FIG. -8 Arteries of the head and neck. Brachiocephalic
artery, right common carotid artery, right subclavian
artery, and their branches. The major arteries to the head
are the common carotid and vertebral arteries.
FIG. -9 Arteries at the base of the brain. The arteries that
compose the circle of Willis are the two anterior cerebral
arteries joined to each other by the anterior
communicating cerebral artery and to the posterior
cerebral arteries by the posterior communicating arteries
Blood-Brain Barrier
The blood-brain barrieris a physiologic barrier between blood capillaries and brain tissue.5
This barrier protects the brain from harmful agents, while allowing nutrients and gases to enter.
The structure of brain capillaries differs from that of other capillaries, so substances that normally
pass into most tissues are prevented from entering brain tissue. Lipid-soluble compounds enter the
brain easily, whereas water-soluble and ionized drugs enter the brain and the spinal cord slowly.
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Thus the blood-brain barrier affects the penetration of drugs. Only certain drugs can enter the CNS
from the bloodstream.
Protective Structures
Meninges
The meninges consist of three protective membranes that surround the brain and spinal cord:
dura mater, arachnoid, and pia mater.
Skull
The skull protects the brain from external trauma. It is composed of eight cranial bones and
14 facial bones. It has many ridges, prominences, and foramina (holes through which blood
vessels and nerves enter the intracranial vault). The largest hole is the foramen magnum,
through which the brainstem extends to the spinal cord. This foramen offers the only major
space for the expansion of brain contents when increased intracranial pressure occurs.
Vertebral Column
The vertebral column protects spinal cord, supports head, & provides flexibility. The vertebral
column is made up of 33 individual vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral
(fused into one), and 4 coccygeal (fused into one). Each vertebra has a central opening through
which the spinal cord passes. Intervertebral discs occupy the spaces between vertebrae. Fig. -10
shows the vertebral column in relation to the trunk.
FIG. -10 The vertebral column (three views).
ASSESSMENT OF NERVOUS SYSTEM
TABLE 5 HEALTH HISTORY
Nervous System
Health Perception–Health Management
 What are your usual daily activities?
 Do you use alcohol, tobacco, or recreational drugs?*
 What safety practices do you perform in a car? On a motorcycle? On a bicycle?
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 Do you have hypertension? If so, is it controlled?
 Have you ever been hospitalized for a neurologic problem?*
Nutritional-Metabolic
 Are you able to feed yourself?
 Do you have any problems getting adequate nutrition because of
 Chewing or swallowing difficulties, facial nerve paralysis, or poor muscle coordination?*
 Give a 24-hr dietary recall.
Elimination
 Do you have incontinence of your bowels or bladder?*
 Do you ever experience problems with hesitancy, urgency, retention?*
 Do you postpone defecation?*
 Do you take any medication to manage neurologic problems? If so, what?
Activity-Exercise
 Describe any problems you experience with usual activities and exercise as a result of a
neurologic problem.
 Do you have weakness or lack of coordination?*
 Are you able to perform your personal hygiene needs independently?*
Sleep-Rest
 Describe your sleep pattern.
 When you have trouble sleeping, what do you do?
Cognitive-Perceptual
 Have you noticed any changes in your memory?*
 Do you experience dizziness, heat or cold sensitivity, numbness, or tingling?*
 Do you have chronicpain?*
 Do you have any difficulty with verbal or written communication?*
 Have you noticed any changes in vision or hearing?*
Self-Perception–Self-Concept
 How do you feel about yourself, about who you are?
 Describe your general emotional pattern.
Role-Relationship
 Have you experienced changes in roles such as spouse, parent, or breadwinner?*
Sexuality-Reproductive
 Are you dissatisfied with sexual functioning?*
 Are problems related to sexual functioning causing tension in an important relationship?*
 Do you feel the need for professional counseling related to your sexual functioning?*
Coping–Stress Tolerance
 Describe your usual coping pattern.
 Do you think your present coping pattern is adequate to meetthe stressors of your life?*
 What needs are unmet by your current support system?
Value-Belief
 Describe any culturally specific beliefs and attitudes that may influence your care.
DIAGNOSTIC STUDIES OF NERVOUS SYSTEM
Numerous diagnostic studies are available to assess the nervous system. Tables 56-8 and 56-9
present the most common studies, and select studies are described in more detail below.
13
Cerebrospinal Fluid Analysis
CSF analysis provides information about a variety of CNS diseases.
o Normal CSF fluid is clear, colorless, odorless, and free of red blood cells and contains little
protein.
o Normal CSF values are listed in Table 56-9. CSF may be obtained through lumbar puncture
or ventriculostomy.
Table -9 Normal Cerebrospinal Fluid Values
Parameter
Specific gravity
pH
Appearance
Red blood cells (RBCs)
White blood cells (WBCs)
Protein
• Lumbar
• Cisternal
• Ventricular
Glucose
Microorganisms
Pressure
Normal Value
1.007
7.35
Clear, colorless
None
0-5 cells/µL (0-5×106 cells/L)
15-45
15-25
5-15
40-70
None
60-150
mg/dL
mg/dL
mg/dL
mg/dL
(0.15-0.45 g/L)
(0.15-0.25 g/L)
(0.05-0.15 g/L)
(2.2-3.9 mmol/L)
mm H2O
Lumbar Puncture
Lumbar puncture is the most common method of sampling CSF. A lumbar puncture is
contraindicated in the presence of increased intracranial pressure or infection at the site of puncture.
Before the procedure,
o Have the patient void.
o The patient is side lying.
o A seated position may also be used.
o Inform the patient that, as a sterile needle is passed between two lumbar vertebrae, he
or she may feel temporary pain radiating down the leg.
o A manometer is attached to the needle to obtain a CSF pressure.
o CSF is withdrawn in a series of tubes and sent for analysis.
o Monitor for headache intensity, meningeal irritation (nuchal rigidity), or signs and
symptoms of local trauma (e.g., hematoma, pain).
FOCUSED ASSESSMENT
Nervous System
Use this checklist to make sure the key assessment steps have been done.
Subjective
Ask the patient about any of the following and note responses.
Blackouts/loss of memory
Weakness, numbness, tingling in arms or legs
Headaches, especially new onset
Loss of balance/coordination
Orientation to person, place, and time
14
YN
YN
YN
YN
YN
Objective: Diagnostic
Check the following laboratory results for critical values.
Lumbar puncture
CT or MRI of brain
EEG
Objective: Physical Examination
Inspect/Observe
General level of consciousness/orientation
Oropharynx for gag reflex and soft palate movement
Peripheral sensation of light touch and pinprick (face, hands, feet)
Smell with an alcohol wipe
Eyes for extraocular movements, PERRLA, peripheral vision, nystagmus
Gait for smoothness and coordination
Palpate
Strength of neck, shoulders, arms, and legs full and symmetric
Percuss
Reflexes
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
Radiologic Studies
Computed Tomography
Computed tomography (CT) scans provide a rapid means of obtaining radiographic images of the
brain (see Fig. 56-15, A). When viewed in succession, these images provide a three-dimensional
representation of the intracranial contents. Denser material appears white, whereas fluid and air
appear dark or black. Brain CT can be completed both with and without contrast media in only a
few minutes.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) provides greater detail than CT and improved resolution
(detail) of the intracranial structures (see Fig. 56-15, B). However, MRI requires a longer time to
complete and may not be appropriate in life-threatening emergencies. Techniques of functional
MRI (fMRI) provide time-related (temporal) images that can be used to evaluate how the brain
responds to various stimuli.
Cerebral Angiography






Cerebral angiography is indicated when vascular lesions or tumors are suspected.
A catheter is inserted into femoral (or brachial) artery and passed through aortic arch and
into the base of a carotid or a vertebral artery for injection of contrast media.
Timed sequence radiographic images are obtained as contrast flows through arteries,
smaller vessels, and veins.
This study can help to identify and localize abscesses, aneurysms, hematomas,
arteriovenous malformations, arterial spasm, and certain tumors.
Because this is an invasive procedure, adverse reactions may occur; patient may have an
allergic (anaphylactic) reaction to the contrast medium.
Once the patient returns to his or her room after the procedure, observe for bleeding at the
catheter puncture site (usually the groin).
15
Electrographic Studies
Electroencephalography





Electroencephalography (EEG) involves recording electrical activity of the surface
cortical neurons of the brain by electrodes placed on specific areas of the scalp.
Specific tests may be done to evaluate brain’s electrical response to lights & loud noises.
This test is done to evaluate not only cerebral disease but also the CNS effects of many
metabolic and systemic diseases.
Among the cerebral diseases assessed by EEG are seizure disorders, sleep disorders,
cerebrovascular lesions, and brain injury.
Prolonged EEG monitoring is becoming a common test to diagnose and treat seizure
disorders. An EEG is noninvasive. Assure patients that there is no risk of electric shock.
Electromyography and Nerve Conduction Studies







Electromyography (EMG) is recording of electrical activity associated with innervation
of skeletal muscle. Needle electrodes are inserted into the muscle to record specific motor
units because recording from the skin is not sufficient.
Normal muscle at rest shows no electrical activity.
Electrical activity occurs only when the muscle contracts.
Activity altered in diseases of muscle (e.g., myopathic conditions) or in disorders of
muscle innervation (e.g., segmental or LMN lesions, peripheral neuropathic conditions).
Nerve conduction studies involve applying a brief electrical stimulus to a distal portion of
a sensory or mixed nerve and recording the resulting wave of depolarization at some point
proximal to the stimulation. For example, a stimulus can be applied to the forefinger and a
recording electrode placed over the median nerve at the wrist.
The time between the stimulus onset and the initial wave of depolarization at the recording
electrode is measured (nerve conduction velocity).
Damaged nerves have slower conduction velocities.
Evoked Potentials
Evoked potentials are recordings of electrical activity associated with nerve conduction along
sensory pathways. The electrical activity is generated by a specific sensory stimulus related to the
type of study (e.g., clicking sounds for auditory evoked potentials, mild electrical pulses for
somatosensory evoked potentials).11
Electrodes placed on specific areas of skin & the scalp record electrical activity. Increases in the
normal time from stimulus onset to a given peak (latency) indicate slowed nerve conduction or
nerve damage.
This technique is useful in diagnosing abnormalities of the visual or auditory systems because it
reveals whether a sensory impulse is reaching the appropriate part of the brain. Indications for
these tests include evaluation of consciousness, multiple sclerosis (optic neuritis), and acoustic
neuroma.
TABLE 6 NORMAL PHYSICAL ASSESSMENT OF NERVOUS SYSTEM
Parameter Findings
 Alert and oriented, orderly thought processes.
Mental
 Appropriate mood and affect.
status
 Smell intact to soap or coffee.
Cranial
 Visual fields full to confrontation.
nerves
 Intact extraocular movements.
16
Motor
system
Sensory
system
Reflexes‡








No nystagmus. Pupils equal, round, reactive to Light and accommodation.
Intact facial sensation to light touch and pinprick.
Facial movements full.
Intact gag & swallow reflexes. Symmetric smile. Midline protrusion of tongue.
Full strength with head turning and shoulder shrugging.
Normal gait and station. Normal tandem walk. Negative Romberg test.
Normal and symmetric muscle bulk, tone, and strength.
Smooth performance of finger-nose, heel-shin movements.

Intact sensation to light touch, position sense, pinprick, heat and cold.

Biceps, triceps, brachioradialis, patellar & Achilles tendon reflexes 2/5
bilaterally.
Downgoing toes with plantar stimulation.

TABLE 7 ASSESSMENT ABNORMALITIES
Nervous System
Finding
Description
Mental Status
Altered consciousness
Anosognosia
Speech
Aphasia, dysphasia
Dysarthria
Eyes
Anisocoria
Diplopia
Homonymous
hemianopsia
Cranial Nerves
Dysphagia
Ophthalmoplegia
Papilledema
Motor System
Apraxia
Ataxia
Dyskinesia
Hemiplegia
Nystagmus
Sensory System
Analgesia
Possible Etiology and Significance
 Stuporous,
mute,
diminished
response to verbalcues or pain
 Inability to recognize bodily defect
or disease
 Intracranial lesions, metabolic
psychiatric disorders
 Lesions in right parietal cortex
 Loss of or impaired language
faculty
(comprehension,
expression, or both)
 Lack of coordination in articulating
speech
 Left cerebral cortex lesion
 Cerebellar or cranial nerve lesion
 Antiseizure drugs, sedatives, hypnotic drug
toxicity (including alcohol)
 Inequality of pupil size
 Double vision
 Loss of vision in one side of visual
field
 Optic nerve injury
 Lesions affecting nerves of extraocular
muscles, cerebellar damage
 Lesions in the contralateral occipital lobe
 Difficulty in swallowing
 Paralysis of eye muscles
 “Choked disc,” swelling of optic
nerve head
 Lesions involving motor pathways of CNs IX,
X (including lower brainstem)
 Lesions in brainstem
 Increase in intracranial pressure
 Inability to perform learned
movements despite having desire
and physical ability to perform
them
 Lack of coordination of movement
 Impairment
of
voluntary
movement,
resulting
in
fragmentary
or
incomplete
movements
 Paralysis on one side
 Jerking or bobbing of eyes as they
track moving object
 Cerebral cortex lesion
 Lesions of sensory or motor pathways,
cerebellum
 Antiseizure drugs, sedatives, hypnotic drug
toxicity (including alcohol)
 Disorders of basal ganglia, idiosyncratic
reaction
to psychotropic drugs
 Stroke and other lesions
involving
motor cortex
 Lesions in cerebellum, brainstem, vestibular
system
 Antiseizure drugs,sedatives, hypnotic toxicity
(including alcohol
 Loss of pain sensation
 Lesion in spinothalamic tract or thalamus,
specific medications
17
disorder,
Anesthesia
 Absence of sensation
Paresthesia
Astereognosis
 Alteration in sensation
 Inability to recognize form of
object by touch
Reflexes
Extensor
plantar
response
Deep tendon reflexes
Spinal Cord
Bladder dysfunction
o Atonic (autonomous)
o Hypotonic
o Hypertonic
Paraplegia
Tetraplegia
(quadriplegia)
 Upgoing
toes
stimulation
 Diminished or
response
with
plantar
absent
motor
 Absence of muscle tone and
contractility, enlargement
 More ability than atonic bladder
but less than normal
 Increase
in
muscle
tone,
diminished
capacity,
reflex
emptying, dribbling, incontinence
 Paralysis of lower extremities
 Paralysis of all extremities
 Lesions in spinal cord, thalamus, sensory
cortex, or peripheral sensory nerve
 Specific medications
 Lesions in the posterior column or sensory
cortex
 Lesions in parietal cortex
 Suprasegmental or upper
motor neuron
lesion
 Lower motor neuron lesions
 Of capacity, no sensation of discomfort,
overflow
 With large residual, inability to voluntarily
empty
 Early stage of spinal cord injury
 Interruption of afferent pathways from bladder
 Lesions in pyramidal tracts (efferent
pathways)
 Spinal cord transaction or mass lesion
(thoracolumbar region)
 Spinal cord transaction or mass lesion
(cervical region)
TABLE 56-8 DIAGNOSTIC STUDIES
Study
Description and Purpose
Cerebrospinal Fluid
Analysis
Nursing Responsibility
CSF is aspirated by needle insertion in L3-4 or
L4-5 interspace to assess many CNS diseases.
Ensure that patient does not have signs
of increased ICP because of the risk of
downward herniation from CSF
removal. Patient assumes and maintains
lateral recumbent position. Use strict
aseptic technique. Ensure labeling of
CSF specimens in proper sequence.
Encourage fluids. Monitor neurologic
signs and VS. Administer analgesia as
needed.
Radiology
Skull and spine xrays
Simple x-ray of skull and spinal column is done
to detect fractures, bone erosion, calcifications,
abnormal vascularity.
Explain that procedure is noninvasive.
Explain positions to be assumed.
Cerebral
angiography
Serial x-ray visualization of intracranial and
extracranial blood vessels
is performed
to detect vascular lesions and tumors of brain
(Fig. 56-14). Contrast medium is used.
Preprocedure: Assess patient for stroke
risk before procedure, since thrombi
may be dislodged during procedure.
Withhold preceding meal. Explain that
patient will have hot flush of head and
neck when contrast medium is injected.
Administer premedication. Explain need
to be absolutely still during procedure.
Postprocedure: Monitor
neurologic
signs and VS every 15-30 min for first 2
hr, every hour for next 6 hr, then every
2 hr for 24 hr. Maintain bed rest until
patient is alert and VS are stable. Report
any neurologic status changes.
Computer-assisted x-ray of
multiple
cross
sections of body parts to detect problems such
as hemorrhage, tumor, cyst, edema, infarction,
brain atrophy & other abnormalities (Fig. 5615, A). Contrast media may be used to enhance
Assess for contraindications to contrast
media, including allergy to shellfish,
iodine, or dye. Explain appearance of
scanner. Instruct patient to remain still
during procedure.
Lumbar puncture
Computed
tomography
scan
(CT)
18
visualization of brain structures.
Magnetic resonance
imaging (MRI)
Imaging of brain, spinal cord, and spinal canal by
means of magnetic energy (Fig 56-15, B). Used
to detect strokes, multiple sclerosis, tumors,
trauma, herniation, and seizures. No invasive
procedures are required. Contrast media may be
used to enhance visualization. Has greater
contrast in images of soft tissue structures than
CT scan.
Screen patient for metal parts and
pacemaker in body. Instruct patient on
need to lie very still for up to 1 hr.
Sedation may be necessary if patient is
claustrophobic
Magnetic resonance
angiography
(MRA)
Uses differential signal characteristics of flowing
blood to evaluate extracranial and intracranial
blood vessels. Provides both anatomic and
hemodynamic information. Can be used in
conjunction with contrast media.
Similar to MRI (see above)
Positron emission
tomography (PET)
Measures metabolic activity of brain to assess
cell death or damage. Uses radioactive material
that shows up as a bright spot on the image (see
Fig. 16-7). Used for patients with stroke,
Alzheimer’s disease,
seizure disorders,
Parkinson’s disease, and tumors.
Explain procedure to patient. Explain that
two IV lines will be inserted. Instruct
patient not to take sedatives or
tranquilizers. Have patient empty
bladderbefore procedure. Patient may be
asked to perform different activities
during test.
Single-photon
emission computed
tomography
(SPECT)
A method of scanning similar to PET, but it uses
more stable substances and different detectors.
Radiolabeled compounds are injected, and their
photon emissions can be detected. Images made
are accumulation of labeled compound. Used to
visualize blood flow or O2 or glucose
metabolism in the brain. Useful in diagnosing
strokes, brain tumors, and seizure disorders.
Similar to PET (see above)
Myelogram
X-ray of spinal cord and vertebral column after
injection of contrast medium into subarachnoid
space. Used to detect spinal lesions (e.g.,
herniated or ruptured disc, spinal tumor).
Preprocedure: Administer sedative as
ordered. Instruct patient to empty
bladder. Inform patient that test is
performed with patient on tilting table
that is moved during test.
Postprocedure: Patient should lie flat for a
few hours. Encourage fluids. Monitor
neurologic signs and VS. Headache,
nausea, and vomiting may occur after
procedure
Electrographic
Studies
Electroencephalogra
phy (EEG)
Electrical activity of brain is recorded by scalp
electrodes to evaluate seizure disorders,
cerebral disease, CNS effects of systemic
diseases, brain death.
Inform patient that
procedure
is
noninvasive and without danger of
electric shock. Determine whether any
medications
(e.g.,
tranquilizers,
antiseizure drugs) should be withheld.
Resume medications and instruct patient
towash electrode paste out of hair after
test.
Magnetoencephalog
raphy (MEG)
Uses a biomagnetometer to detect magnetic fields
generated by neural activity. It can accurately
pinpoint the part of the brain involved in a
stroke, seizure, or other disorder or injury.
Measures extracranial magnetic fields and
scalpelectric field (EEG).
MEG, a passive sensor, does not make
physical contact with patient. Explain
procedure to patient.
Electromyography
(EMG) and nerve
conduction studies
Electrical activity associated with nerve and
skeletal muscleis recorded by insertion of
needle electrodes to detect muscle and
peripheral nerve disease.
Inform patient that pain and discomfort
are associated with insertion of needles.
Evoked potentials
Electrical activity associated with nerve
conduction along sensory pathways is recorded
by electrodes placed on skin and scalp.
Stimulus generates the impulse.
Explain procedure to patient.
19
Procedure is used to diagnose disease (e.g.,
multiple sclerosis), locate nerve damage, and
monitor function intraoperatively.
Ultrasound
Carotid
duplex
studies
Combined ultrasound and pulsed Doppler
technology. Probe is placed over the carotid
artery and slowly moved along the course of the
common carotid artery. Frequency of reflected
ultrasound signal corresponds to the blood
velocity. Increased blood flow velocity can
indicate stenosis of a vessel.
Explain procedure to patient. Duplex
scanning is anoninvasive study that
evaluates the degree of stenosis of the
carotid and vertebral arteries
Transcranial
Doppler
Same technology as carotid duplex, but evaluates
blood flow velocities of the intracranial blood
vessels. Probe is placed on the skin at various
“windows” in the skull (areas in the skull that
have only thin bony covering) to register
velocities of the blood vessels.
Explain procedure to patient. Noninvasive
technique that is useful in assessing
vasospasm
associated
with
subarachnoid
hemorrhage,
altered
intracranial blood flow dynamics
associated with occlusive vascular
disease, presence of emboli & cerebral
autoregulation.
21