Chapter 17
Disorders of the Central and
Peripheral Nervous Systems and the
Neuromuscular Junction
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Brain Trauma

Traumatic brain injury

A traumatic insult to the brain possibly producing
physical, intellectual, emotional, social, and
vocational changes
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At-Risk Individuals






Infants 6 months to 2 years
School-age children
Adolescents and young adults 15 to 35 years
of age
People more than 70 years of age
Men 1.5 times as likely to sustain a TBI
Persons living in high-crime areas
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Brain Trauma

Blunt (closed, nonmissile) trauma

Head strikes hard surface or a rapidly moving
object strikes the head
 The dura remains intact; brain tissues not exposed
to the environment
 Causes focal (local) or diffuse (general) brain
injuries

Open (penetrating, missile) trauma


Injury breaks the dura and exposes the cranial
contents to the environment
Causes primarily focal injuries
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Brain Trauma


Compound fractures
Basilar skull fracture
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Brain Trauma
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Causes of Brain Injury






Falls 28%
Motor vehicle crashes 20%
Moving objects or moving against stationary
objects 19%
Assault 11%
Sports-related events
Blasts (military active duty personnel)
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Severity of Brain Injury



75% to 90% of head injuries not severe
Focal brain injury and diffuse axonal injury (DAI)
each account for half of all injuries
Focal brain injury accounts for more than two
thirds of head injury deaths; DAI less than one
third of deaths

DAI accounts for the greatest number of severely
disabled survivors
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Severity of Brain Injury

Hallmark of severe brain injury

Loss of consciousness for six or more hours
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Focal Brain Injury



Observable brain lesion
Cerebral edema
Coup injury


Injury directly below the point of impact
Contrecoup

Injury on the pole opposite the site of impact
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Focal Brain Injury


Force of impact typically produces contusions
Contusions can cause:




Extradural (epidural) hemorrhage or hematoma
Subdural hematoma
Intracerebral hematoma
Clinical manifestations of contusion
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Extradural Hematoma





85% arterial bleeding
15% meningeal vein or dural sinus injury
90% have a skull fracture
The temporal fossa is the most common site
of extradural hematoma caused by injury to
the middle meningeal artery or vein
Clinical manifestations of hematoma
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Subdural Hematoma




10% to 20% of persons with traumatic brain
injury
MVAs are the most common cause
50% of subdural hematomas associated with
skull fractures
Falls (older adults, substance abuse)
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Subdural Hematoma

Acute



Develops within 48 hours
Often located at the top of the skull
Chronic

Develops over weeks to months
• Older adults
• Alcohol abuse
• 80% complain of chronic headaches and have tenderness at
site of injury
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Intracerebral Hemorrhage


Associated with MVA and falls
Intracerebral hemorrhage and resultant
hematoma acts as an expanding mass

Increased ICP and compression of brain tissues
with resultant edema
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Diffuse Brain Injury

DAI




Shaking, inertial effect
Acceleration/deceleration
Axonal damage
• Shearing, tearing, or stretching of nerve fibers
Severity corresponds to the amount of shearing
force applied to the brain and brainstem (mild,
moderate, severe)
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Diffuse Brain Injury

Concussions


Mild concussion
Classical concussion
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Mild Concussion

Temporary axonal disturbances causing
attention and memory deficits but no loss of
consciousness

I—confusion, disorientation, and momentary
amnesia
 II—momentary confusion and retrograde amnesia
 III—confusion with retrograde and anterograde
amnesia
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Classic Cerebral Concussion

Grade IV

Disconnection of cerebral systems from the
brainstem and reticular activating system
 Physiologic and neurologic dysfunction without
substantial anatomic disruption
 Loss of consciousness (<6 hours)
 Anterograde and retrograde amnesia
 Uncomplicated (no focal injury)
 Complicated (focal injury)
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Postconcussive Syndrome


Headache, cognitive impairments,
psychologic and somatic complaints, cranial
nerve signs and symptoms
Treatment


Reassurance and symptomatic relief
Close observation for 24 hours by a reliable
individual so immediate intervention can be
obtained if delayed effects become severe
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Spinal Cord Trauma

Commonly occurs from vertebral injuries



Traumatic injury of vertebral and neural tissues
due to compressing, pulling, or shearing forces
Most common locations: cervical (1, 2, 4-7),
and T1-L2 lumbar vertebrae


Simple fracture, compressed fracture, and
comminuted fracture
Locations reflect most mobile portions of vertebral
column and the locations where the spinal cord
occupies most of the vertebral canal
Primary vs. secondary injury
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Spinal Cord Trauma
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Spinal Cord Trauma
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Spinal Cord Trauma

Spinal shock


Normal activity of the spinal cord ceases at and
below the level of injury; sites lack continuous
nervous discharges from the brain
Complete loss of reflex function (skeletal, bladder,
bowel, sexual; thermal control; autonomic control)
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Spinal Cord Trauma

Neurogenic shock

Loss of sympathetic outflow
• Vasodilation
• Hypotension
• Bradycardia
• Hypothermia
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Spinal Cord Trauma



Paraplegia
Quadriplegia
Autonomic hyperreflexia (dysreflexia)

Massive, uncompensated cardiovascular
response to stimulation of the sympathetic
nervous system
 Stimulation of the sensory receptors below the
level of the cord lesion
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Spinal Cord Trauma

Chemical and metabolic changes in tissues

Release of toxic excitatory amino acids, accumulation
of endogenous opiates, lipid hydrolysis with
production of active metabolites, and local free radical
release
 Produce further ischemia, vascular damage, and
necrosis of tissues
 Necrosis consumes 40% of cross-sectional cord
within 4 hours of trauma and 70% within 24 hours
 Cord swelling increases degree of dysfunction
• Distinguishing functions to be lost permanently from those
that are impaired temporarily becomes difficult
• In the cervical region, cord swelling may be life threatening
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Autonomic Hyperreflexia
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Degenerative Disorders of the
Spine

Degenerative disk disease (DDD)





Spondylolysis
Spondylolisthesis
Spinal stenosis
Low back pain
Herniated intervertebral disk
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Cerebrovascular Disorders

Cerebrovascular accidents (CVAs)

Thrombotic stroke
• Arterial occlusions caused by thrombi formed in arteries
supplying the brain or in intracranial vessels
• Transient ischemic attacks

Embolic stroke
• Fragments that break from a thrombus formed outside
the brain
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Cerebrovascular Disorders




Hemorrhagic stroke (ICH)
Lacunar stroke
Cerebral infarction
Cerebral hemorrhage
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Cerebrovascular Disorders

Intracranial aneurysm




Saccular (berry) aneurysms
Fusiform (giant) aneurysms
Mycotic aneurysms
Traumatic aneurysms
• Dissecting aneurysms
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Intracranial Aneurysm
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Cerebrovascular Disorders

Vascular malformations




Cavernous angiomas
Capillary telangiectasis
Venous angioma
Arteriovenous malformation
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Cerebrovascular Disorders

Subarachnoid hemorrhage


Manifestations



Blood escapes from defective or injured
vasculature into the subarachnoid space
Kernig sign
Brudzinski sign
Risk factors
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Headache

Migraine headache



Trigger factors
Aura
Cluster headache

Several attacks can occur during the day for days
followed by a long period of spontaneous
remission
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Headache

Chronic paroxysmal hemicrania


Cluster-type headache that occurs with more daily
frequency but with shorter duration
Tension-type headache

Mild to moderate bilateral headache with a
sensation of a tight band or pressure around the
head
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Central Nervous System Tumors

Cranial tumors


Primary intracerebral tumors (gliomas)
• Astrocytoma
• Oligodendroglioma
• Ependymoma
Primary extracerebral tumors
• Meningioma
• Nerve sheath tumors
• Metastatic carcinoma
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Central Nervous System Tumors

Spinal cord tumors



Intramedullary tumors
Extramedullary tumors
• Intradural
• Extradural
Manifestations
• Compressive syndrome
• Irritative syndrome
• Syringomyelic syndrome
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Spinal Cord Tumors
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Infection and
Inflammation of the CNS

Meningitis




Bacterial meningitis
Aseptic (viral, nonpurulent, lymphocytic)
meningitis
Fungal meningitis
Tubercular (TB) meningitis
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Infection and
Inflammation of the CNS

Suppurative cerebral masses


Cerebral abscess
Spinal cord abscess
• Intramedullary spinal cord abscess
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Infection and
Inflammation of the CNS

Encephalitis


Acute febrile illness, usually of viral origin with
nervous system involvement
Most common forms of encephalitis are caused by
arthropod-borne viruses and herpes simplex virus
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Neurologic Complications of
AIDS








HIV-associated cognitive dysfunction
HIV myelopathy
HIV neuropathy
Aseptic viral meningitis
Opportunistic infections
Cytomegalovirus infections
Parasitic infection
CNS neoplasms
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HIV Dementia




Affects adults and children
Insidious and unpredictable course
Impaired concentration, short-term memory,
retrieval
Generalized cognitive system deficits

Occur later
 Psychomotor slowing
 Decreased speech spontaneity and fluency
 Progressive loss of balance, ataxia, spastic paraparesis
or paralysis, and generalized hyperreflexia
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Lyme Disease



Tick-borne spirochete bacterial infection
Borrelia burgdorferi
Progression



Introduced by tick bite
Incubates 3 to 32 days
Migrates to skin, lymph nodes, and other body
systems
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Lyme Disease

Stages



1 Bull's eye rash
2 Cardiac and neurological manifestations
3 MS, enhanced neurological manifestations
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Demyelinating Disorders

Multiple sclerosis (MS)



Progressive, inflammatory, demyelinating,
autoimmune disorder of the CNS
Degeneration of the myelin sheath in CNS
neurons
Types
• Mixed (general)
• Spinal
• Cerebellar
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Neurodegenerative Disorders

Amyotrophic lateral sclerosis (ALS)
Classic ALS—Lou Gehrig’s disease
 Diffusely affects upper and lower motor neurons of
the cerebral cortex, brainstem, and spinal cord
(corticospinal tracts and anterior roots)
 Progressive weakness leading to respiratory
failure and death
 Person has normal intellectual and sensory
function until death

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Peripheral Nervous System
Disorders

Neuropathies



Generalized symmetric polyneuropathies
• Distal axonal polyneuropathy
• Demyelinating polyneuropathy
Generalized neuropathies
• Sensory neuropathies
Focal or multifocal neuropathies
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Peripheral Nervous System
Disorders

Guillain-Barré syndrome



Acquired inflammatory disease causing
demyelination of the peripheral nerves with
relative sparing of axons
Acute onset, ascending motor paralysis
Humoral and cellular immunologic reaction
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Peripheral Nervous System
Disorders

Radiculopathies



Radiculitis
• Inflammation of the spinal nerve roots
Radicular pain
Plexus injures

Involves the nerve plexus distal to the spinal roots
but proximal to the formation of the peripheral
nerves
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Neuromuscular Junction
Disorders

Myasthenia gravis



Chronic autoimmune disease
IgG antibody produced against acetylcholine
receptors (antiacetylcholine receptor antibodies)
Weakness and fatigue of muscles of the eyes and
the throat, causing diplopia, difficulty chewing,
talking, swallowing
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Neuromuscular Junction
Disorders

Myasthenia gravis



Classification
• Neonatal myasthenia
• Congenital myasthenia
• Juvenile myasthenia
• Ocular myasthenia
• Generalized autoimmune myasthenia
Myasthenia crisis
Cholinergic crisis
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