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Nervous System Diseases and Disorders 327
Coup
lesion
Figure 15-12 Coup and contracoup lesions.
Fractures in other areas can lead to hemiparesis and
seizures. Another potential problem is infection of the
brain tissue through the fracture site.
■ Diagnosis. Diagnosis is made on the basis of clini
cal history, physical examination, cranial X-rays, and
CT scan.
■ Treatment. Treatment depends on the type and position
of the fracture. A craniotomy (cranio = skull, otomy =
incision) might be performed to relieve ICP due to swell
ing. Surgical repair of the fracture might be performed if
the fractured bone is pressing on the brain tissue. Protective
headgear might be needed until the fracture site is healed.
Figure 15-13 (A) Common sites and types of skull fractures. (B) Skull fracture (X-ray).
Chapter 15
■ Prevention. Preventive actions include practicing
safety measures and avoiding risky activities to prevent
head injury.
Epidural and Subdural Hematomas
■ Description. An epidural hematoma is a collection
of blood between the skull and dura mater, the thin
membrane that covers the brain. Epidural hematomas
occur more often in young adult males. A subdural
hematoma is a collection of blood between the outer
(dura mater) layer and the middle (arachnoid) layer.
Subdural hematomas occur twice as often as epidural
hematomas.
■ Etiology. A blow to the head, such as might be
obtained in a fight or accident, is the common cause
of an epidural (EP-ih-DOO-ral); epi = above, dural =
dura, outer meninges) hematoma. Blood vessels are
ruptured and hemorrhage or seep blood between the
bony skull and the first, or outer, meninges, the dura
mater (Figure 15-14). Blood usually collects rapidly
Skull
Arachnoid
Pia mater
Epidural hematoma Subdural hematoma
Dura mater
(A)
(B)
Figure 15-14 (A) Epidural and (B) subdural hematomas. (C) CT of epidural hematoma. (D) CT of subdural hematoma.
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Nervous System Diseases and Disorders 329
over a period of hours, pushing the dura away from the
inner bony skull.
A subdural (SUB-DOO-ral) hematoma is usually
the result of the head hitting a stationary object, as is
often seen with falls, characterized by striking the head
on the floor or a solid object. Subdural hematomas are
characterized by blood collecting between the outer
(dura mater) layer and the middle (arachnoid) layer.
Subdural hematomas generally develop more slowly
over a period of days.
■ Symptoms. Symptoms of an epidural hematoma
occur within a few hours after injury and can include
headache, dilated pupils, nausea, vomiting, and dizzi
ness. As the hematoma grows, the individual might lose
consciousness and develop an increase in ICP.
Symptoms of a subdural hematoma are due to
increased ICP. Symptoms might include hemiparesis,
nausea, vomiting, dizziness, convulsions, and loss of
consciousness.
■ Diagnosis. Diagnosis of a cerebral hematoma is made
on the basis of clinical history, cranial X-ray, or CT or
MRI scan. Hematomas, generally, are accompanied by
a skull fracture.
■ Treatment. Treatment of epidural and subdural
hematomas is aimed at decreasing ICP. Pressure can
be relieved by a special craniotomy called burr holes to
drain the blood and cauterization (KAW-ter-eye-ZAY-
shun; electrical burning of tissue) to stop the bleeding.
If ICP is treated promptly, prognosis is good. Untreated,
increased ICP can be fatal.
■ Prevention. Preventive actions include activities to
prevent head injury.
Spinal Cord Injury: Quadriplegic and
Paraplegia
■ Description. The spinal cord is protected by the bony
vertebral column. When this column is fractured or
injured, the spinal cord also can suffer injury. The spinal
cord can be injured at any level, but the mobility of the
neck causes this area to be the most vulnerable. The site
of the injury, the type of trauma, and the degree of injury
will all play a role in determining whether paralysis will
occur and whether it will be temporary or permanent.
Paralysis of the lower part of the body including both
legs is called paraplegia. If the body and both arms and
both legs are affected, it is called quadriplegia.
■ Etiology. The leading cause of spinal cord injury is
automobile accidents. After age 65 the most common
cause is due to falls. Other causes are gunshot and
knife wounds, falls, and recreational and sports
injuries.
■ Symptoms. Injury to the spinal cord can result in
varying degrees of loss of movement and feeling below
the area of injury. If the damage to the spinal cord is
severe, there is little or no hope of regaining movement
and feeling. Paralysis, initially, results in the inability to
move the extremities; but with time, reflex functions
might return, leading to spastic movements. Refer to
Figure 15-12 while reading the following material for
a better understanding of spinal cord injuries and pre
ventive measures.
Injury to the neck is common in automobile acci
dents and sports accidents. Automobile accidents com
monly lead to injury in the form of whiplash.
Injury to the highest level of the cervical spine
(C1-C3) is usually fatal. Injuries to the cervical spine or
neck area (C1-C4) can lead to quadriplegia (KWAD-
rih-PLEE-jee-ah; quadri = four, plegia = paralysis).
Quadriplegia is the loss of movement and feeling in
the trunk and all four extremities with the accom
panying loss of bowel, bladder, and sexual function.
Other life-threatening symptoms include hypotension,
hypothermia (hypo = low, thermia = heat or tem
perature), bradycardia, and respiratory problems. In
some cases, respirations must be permanently assisted
with mechanical ventilation. Injury to the lower cervi
cal spine (C5-C7) can lead to varying degrees of paral
ysis of the arms and shoulders.
Injury to the thoracic or lumbar section of the
spinal cord can lead to paraplegia (PAR-ah-PLEE-
jee-ah; para = beyond or two like parts, plegia =
paralysis), a loss of movement and feeling in the
trunk and both legs. Loss of bladder, bowel, and sex
ual function is common. Paraplegia is often the result
of a fall or an injury resulting in compression to the
lower spine.
■ Diagnosis. Diagnosis is made on the basis of his
tory of the injury and physical examination along with
X-rays, CT scan, MRI, and myelography.
■ Treatment. Treatment of suspected spinal cord injury
victims includes seeking emergency medical treatment
immediately and not moving the victim unless the sur
roundings are unsafe or life-threatening as in the case
of fire or flood. The head and neck should be moved
only in life-threatening situations such as choking or
respiratory arrest. Movement at this time should be
very cautious. Emergency medical treatment is aimed
330 Chapter 15
at maintaining the position of the spine by limiting
movement with use of special collars and backboards.
The head, neck, and spine are stabilized prior to trans
porting in an emergency vehicle.
Hospitalization includes diagnosis and treatment
of the injury, including medications, emergency sur
gery, and, often, immobilization with traction or
traction-like devices. Much of the early treatment is
aimed at preventing further spinal cord injury.
Further treatment can include surgery to realign
and stabilize the bony spinal column and decompress,
or release, pressure on the spinal cord. Early and inten
sive rehabilitation is necessary for the best prognosis.
Generally, the earlier the treatment is begun, the better
the prognosis.
During treatment, medical attention must also
focus on preventing problems that arise from immobi
lization, including muscle wasting, contractures, decu
bitus (commonly called bed sores), blood clots, and
urinary tract infections.
Long-term care includes rehabilitation and sup
portive treatment, which might include medications,
electric wheelchair, computer devices, and ventilator
support.
■ Prevention. Preventive actions include activities to
prevent spinal cord injury as shown in Figure 15-15.
Rare Diseases
Although some of the disorders discussed in this section
are familiar to the public due to their exposure in the
media and to intensive solicitations for research, they
are actually rare diseases of the nervous system, con
sidering all the various disorders that affect this system.
Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS), also known as Lou
Gehrig’s disease, is a destructive disease of the motor,
or movement, neurons. The cause of ALS is unknown,
although genetic and viral-immune factors have been
suggested.
ALS is characterized by atrophy of the muscles,
leading to a progressive loss of movement of the hands,
arms, and legs. As the disease progresses, loss of muscle
function in the face and chest area leads to difficulty
talking, chewing, swallowing, and breathing. Eventu
ally, the loss of motor function causes quadriplegia.
One distinguishing factor of ALS is that there is not
a loss of sensory neurons. The individual can feel the
extremities, but movement is impaired. Mental func
tion is unaffected, so the affected individual is aware of
the condition and can take an active role in planning
care. ALS usually affects men twice as often as it affects
women, with onset of the disease after age 50.
Treatment is supportive because there is no cure
for ALS. Management of respiratory complications is
vital because most individuals affected with ALS die of
respiratory failure. ALS is eventually fatal, with death
usually occurring four to six years after onset. In some
cases, affected individuals have remained active for 10
to 20 years after onset.
Guillain-Barre Syndrome
Guillain-Barre syndrome is an acute, progressive dis
ease affecting the spinal nerves. The cause of this disease
is unknown, but it is suggested to be an autoimmune
disorder because the symptoms usually begin 10 to
21 days after a febrile illness such as a respiratory infec
tion or gastroenteritis.
Early symptoms include nausea, fever, and mal
aise. Within 24 to 72 hours, paresthesia (PAR-es-TH-
EE-see-ah; abnormal sensation, burning, tingling, or
numbness), muscle weakness, and paralysis usually
begin. These symptoms generally begin in the legs and
move upward but can also start in the face and arms and
move downward.
Guillain-Barre syndrome becomes life-threaten
ing if respiratory muscles are involved. Symptoms can
progress for several days to some weeks. When pro
gression ceases, recovery begins and can require 3 to
12 months. Treatment is supportive. Recovery is usually
complete.
Huntington’s Disease
Huntington’s disease, also known as Huntington’s cho
rea, is an inherited disease. It is a dominant gene dis
order affecting 50% of all children in families in which
one parent has Huntington’s. This disorder does not
appear until middle age, so children are often grown
before the parent shows symptoms.
Symptoms of Huntington’s consist of a pro
gressive degeneration of the brain, characterized by
loss of muscle control and chorea, a constant, jerky,
uncontrollable movement. The disease also leads to
mental deterioration with symptoms of personality
change, moody behavior, and loss of memory. Over
a period of years, dementia (total mental incapacita
tion) occurs.
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Cervical spine, magnified
Diving
4
Falls
Sports injuries
11
Automobile
accidents
Horseback riding
2
5
5
6
7
Sacrum
Coccyx
Lumbar
vertebrae
5-7
Weakness in
shoulders and
arms
3
4
Home accidents
Falls that compress
the vertebra
3
1-3
Usually
fatal
4
Quadriplegia
Do not dive
into unfamiliar water
Check water depth
before diving
Wear safety helmets
Thoracic
vertebrae
10
T1-L5
Paraplegia
Wear seat belts
Wear protective gear
when participating
in sports activities
Secure ladders
and do not stand on
the top platform
Seek assistance
with activities that
require climbing
Figure 15-15 Spinal cord injuries.
332 Chapter 15
There is no cure for Huntington’s disease. Treat
ment is supportive and protective, with institutionaliza
tion often necessary to provide the needed care. Genetic
counseling is needed in families with this inheritance
pattern.
Multiple Sclerosis
Multiple sclerosis (MS) is a disease that causes demy
elination of the nerves of the CNS. Myelin, remember,
acts as an insulator around nerves, much like the insu
lation around an electric cord. Demyelination allows
information to leak from the nerve pathway, leading to
poor or absent nerve transmission.
The cause of MS is not clear. It is thought that
a genetic predisposition plays some part because it
appears to pass through families and the risk of devel
opment is higher in siblings and children of persons
with the disease. It is also believed that the immune
system and viral infection play a part.
Symptoms caused by demyelinating lesions are
muscle weakness, lack of coordination, paresthesia,
speech difficulty, loss of bladder function, and visual
disturbance, especially diplopia (double vision). Symp
toms are varied, depending on the location of the
lesions, making diagnosis difficult.
MS usually affects young adults between the ages
of 20 and 40 years. It is characterized by periods of
remission and exacerbation, usually over a period of
several years.
Physical therapy and muscle relaxants can be help
ful to maintain muscle tone and reduce spastic move
ment. The severity of the disease varies from individual
to individual, but generally speaking, most affected
individuals live a normal life span.
Effects of Aging on the System
The effects of aging on the nervous system are some
of the most noticeable to the older adult. With aging,
there is a decrease in nervous system activity in the
brain and spinal cord due to a loss of neurons and
shrinkage of the hypothalamus. Research has shown
that continued active use of the brain decreases this
process to some extent, but some changes still occur.
With these changes in the brain and spinal cord come
many changes in the individual’s functioning, for
instance, a loss in short-term memory but not in long
term memory. There is also a slower general reaction
time. The older person also might have difficulty com
pleting fine motor skills. General touch perception is
somewhat diminished, too, so the individual might
have difficulty distinguishing temperature changes
and pain stimuli.
Vision ability is one of the first changes the indi
vidual often notices. There is a loss of visual acuity and
a decrease in peripheral vision. Some individuals also
become intolerant of very bright light and have diffi
culty adapting to changes in light from dark to bright.
Some hearing loss is a subtle process that occurs at
different levels in individuals. Taste sensation also can
diminish over time.
Sleep patterns are usually affected in the aging pro
cess. Generally, the older adult does not sleep as well at
night but makes up for this deficit by taking short naps
throughout the day or in the early evening.
Summary
T
he nervous system is a highly complex system responsible for the individual’s ability to reason, interact with other
individuals, understand complex ideas, and respond both intellectually and physically. Disorders of the system usu
ally result in symptoms involving many other systems.
Injuries to the brain, neck, and spinal cord are a main cause of disability and death nationwide. Permanent
neurologic deficits are common in brain and spinal cord injuries.
Changes in the nervous system with aging result in some of the most commonly seen symptoms; losses in
the senses are the most noticeable problems. Changes in vision and hearing are some of the earliest symptoms
realized by the middle-aged individual. Alzheimer’s disease is one of the most common disorders of the nervous
system diagnosed today.
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Nervous System Diseases and Disorders 333
Review Questions
Short Answer
1. What are the functions of the nervous system?
2. Which signs and symptoms are associated with common nervous system disorders?
3. Which diagnostic tests are most commonly used to determine the type and cause of nervous system disorders?
Matching
4. Match the disorders listed in the left column with the correct description in the right column:
_________ Encephalitis
________ Tetanus
________ Meningitis
________ TIA
_________ Cephalalgia
_________ Concussion
________ Contusion
_________ Subdural hematoma
_________ Alzheimer’s disease
a. Inflammation of the covering of the brain and spinal cord
b. A disorder affecting the seventh cranial nerve
c. Disruption in the electrical activity of the brain, causing unconsciousness
d. Blood collection between the dura mater and arachnoid layer of the brain
e. Physical bruising of the brain
f. Infection of nerve tissue
g. Disease characterized by the demyelination of nerves of the CNS
h. Inflammation of brain tissue
i. Headache
_________ ALS
_________ MS
________ Bell’s palsy
j. A neurodegenerative disease characterized by cognitive dysfunction
k. Destructive disease of the motor neurons
l. Mild stroke
True or False
5. T F With aging, there is a decrease in nervous system activity.
6. T F As an individual ages changes in functioning in the nervous system might cause some short-term
memory loss.
7. T F Fine motor skills and not affected by aging.
8. T F Some of the first changes the individual usually notices with aging are visual acuity losses.
334 Chapter 15
Case Studies
■ Mr. Speed is a 57-year-old gentleman who has been recently diagnosed with Alzheimer’s disease. He is in
the early stage of the disease at this point. Mrs. Speed is quite concerned about the progression of the disease,
whether Mr. Speed can still be employed, if he can be left alone for several hours at a time, and what medica
tions he will be required to take. How would you respond to her concerns? Is there other information that would
be helpful to the Speeds? Where can they find more information about Alzheimer’s disease?
■ Mrs. Simpson, age 56, comes to the clinic for her yearly routine physical examination. She asks you about
receiving the vaccine for shingles that she heard about on television. She thought she should get it because
her sister had shingles a year ago. Mrs. Simpson stated that her sister really suffered with the disease, and she
does not want to have that same experience. What can you tell her about the vaccine? Is she a candidate for
Zostavax®? Who should receive the vaccine? Where can she find more information about this vaccine?
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16
Eye and Ear
Diseases and
Disorders
Key Terms
Amblyopia (p. 347)
Angiography (p. 339)
Audiometry (p. 340)
Cerumen (p. 337)
Diplopia (p. 347)
Enucleation (p. 359)
Mastoidectomy (p. 354)
Myringotomy (p. 351)
Ophthalmoscope
(p. 338)
Otalgia (p. 350)
Otoscope (p. 339)
Photophobia (p. 345)
Prosthesis (p. 355)
Pruritus (p. 352)
Purulent (p. 352)
Radial keratotomy (RK)
(p. 342)
Stapedectomy (p. 355)
Suppurative (p. 350)
Tinnitus (p. 353)
Tonometry (p. 339)
Topical (p. 346)
Tympanoplasty (p. 351)
Tympanostomy (p. 351)
Vertigo (p. 350)
Learning Objectives
Upon completion of the chapter, the learner should be able to:
1. Define the terminology common to the eye
and ear.
2. Discuss the basic anatomy and physiology of the
eye and ear.
3. Identify the important signs and symptoms
associated with common eye and ear disorders.
5. Identify common disorders of the eye and ear.
6. Describe the typical course and management of
the common eye and ear disorders.
7. Describe the effects of aging on the eye and ear
and the common disorders associated with aging
of these organs.
4. Describe the common diagnostics used to
determine the type and cause of eye and ear
disorders.
Overview
T
he eyes and ears are the major sensory organs of the body. They are extremely important to most individ
uals to maintain quality of life and ease of functioning. However, although sensory deficits affect many
people adversely, a high-quality lifestyle is still possible after sensory losses. Individuals with visual and hear
ing impairment learn to function extremely well in activities of daily living. Disorders of the sensory organs
are frequently the result of other system problems. Early detection of vision or hearing impairment can pre
vent permanent loss of these senses. ■
335
336 Chapter 1 6
Anatomy and Physiology
The eye and ear are sensory organs that perform highly
complex functions in the individual. They each are
unique in their structure and function.
Eye
The eyeball is the sensory organ of sight located in the
bony orbit of the skull. It is about 1 inch in diameter
and consists of extraocular and intraocular structures
(Figure 16-1). The extraocular structures include:
■ Muscles that hold the eyeball in place and facili
tate movement of the eyeball
■ Superior and inferior rectus—move eye up and
down
■ Medial and lateral rectus—move eye toward the
nose and toward the temple
■ Superior and inferior oblique—move the eye to
the right and left vertically
■ Cranial nerves that innervate the eye and its
structures
■ Optic (II)
■ Oculomotor (III)
■ Trochlear (IV)
■ Trigeminal (V)
■ Abducens (VI)
■ Facial (VII)
■ Eyelids that cover the anterior portion of the eyeball,
regulate light entering the eye, protect the eye, and
lubricate the eye
■ Conjunctivae (clear transparent membranes) to pro
tect the eye from foreign objects
■ Lacrimal glands (tear glands) to clean and moisten
the eye
Consider This...
1
Humans are the only animals that produce
emotional tears.
The intraocular structures consist of some parts of
the eye that are visible externally and some parts visi
ble only through an ophthalmoscope. The intraocular
structures include:
■ Sclera—white area covering the outside of the eye
except over the pupil and iris
■ Cornea—clear tissue covering the pupil and iris
Ciliary body
and muscle
Suspensory
ligament
Conjunctiva
Iris
Pupil
Anterior chamber
of anterior cavity
(aqueous humor)
Cornea
Lens
Canal of Schlemm
Posterior cavity
(vitreous humor)
Sclera
Choroid
Optic disc
(blind spot)
Blood vessels
Retina
Retinal arteries
and veins
Fovea
centralis
Macula
lutea
------ Optic
nerve
External eye muscle
Figure 16-1 The eyeball: cross-sectional view.
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