C h a p t e r 3 6
Disorders of Neuromuscular Function
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skin integrity are pressure, shearing forces, and local-
ized trauma and irritation. Relieving pressure, allowing
adequate circulation to the skin, and skin inspection are
primary ways of maintaining skin integrity. Of all the
complications after SCI, skin breakdown is the most
preventable.
Future Directions in Repair of the Injured
Spinal Cord
There is a continued effort to determine new and
innovative strategies for repairing the injured spinal
cord.
7,67–71
At present, these strategies focus on pro-
moting the regrowth of interrupted nerve fiber tracts,
using nerve growth–stimulating factors or molecules
that suppress inhibitors of neuronal extension; bridg-
ing spinal cord lesions with scaffolds that are impreg-
nated with nerve growth factors, which promote
axon growth and reduce the barriers caused by scar
tissue; repairing damaged myelin and restoring nerve
fiber conductivity in the lesion area; and enhancing
CNS plasticity by promoting compensatory growth of
spared, intact nerve fibers above and below the level
of injury. Stem cell transplantation offers a promis-
ing therapeutic strategy for spinal cord injury repair.
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Although these strategies may not allow for complete
repair of the spinal cord or to recreate what was pres-
ent before the injury, even small successes may be use-
ful for someone with SCI.
R E V I EW E X E R C I S E S
1.
A 32-year-old woman presents with complaints
of “drooping eyelids,” difficulty chewing and
swallowing, and weakness of her arms and legs
that is less severe in the morning but becomes
worse as the day progresses. She complains that
climbing stairs and lifting objects are becoming
increasingly difficult. Clinical examination
confirms weakness of the eyelid and jaw muscles.
She is told that she may have myasthenia gravis
and is scheduled for testing using the short-acting
acetylcholinesterase inhibitor edrophonium
(Tensilon).
A.
Explain the pathogenesis of this woman’s
symptoms as it relates to myasthenia gravis.
B.
Explain how information from the
administration of the acetylcholinesterase
inhibitor edrophonium can be used to assist in
the diagnosis of the disorder.
2.
A 20-year-old man suffered spinal cord injury at
the C2 to C3 level as the result of a motorcycle
accident.
A.
Explain the effects of this man’s injury on
ventilation and communication; sensorimotor
function; autonomic nervous system function;
bowel, bladder, and sexual function; and
temperature regulation.
B.
Autonomic dysreflexia, which is a threat to
persons with spinal cord injuries at T6 or
above, is manifested by hypertension, often to
extreme levels, and bradycardia; constriction
of skin vessels below the level of injury; and
severe headache and nasal stuffiness. Explain
the origin of the elevated blood pressure and
bradycardia. The condition does not occur
until spinal shock has resolved, and usually
occurs only in persons with injuries at T6 and
above. Explain.
SUMMARY CONCEPTS
■■
Upper motor neuron (UMN) lesions are those
involving neurons completely contained in the
central nervous system (CNS).
■■
Amyotrophic lateral sclerosis is a progressive and
devastating neurologic disorder that selectively
affects motor function. It affects lower motor
neurons (LMNs) in the spinal cord as well as
UMNs in the brain stem and cerebral cortex.
■■
Multiple sclerosis is a slowly progressive
demyelinating disease of the CNS that is
characterized by exacerbations and remissions
of paresthesias, optic neuritis, and motor
weakness.
■■
Spinal cord injury (SCI) is a disabling neurologic
condition of UMNs in the spinal cord that
produces various degrees of sensorimotor
loss and altered reflex activity based on the
level of injury and extent of cord damage.
Depending on the level of injury, SCI is
associated with ventilation and communication
problems; autonomic nervous system
dysfunction that predisposes to the vasovagal
response, autonomic hyperreflexia, impaired
body temperature regulation, and postural
hypotension; impaired muscle pump and venous
innervation leading to edema of dependent areas
of the body and risk for deep vein thrombosis;
altered sensorimotor integrity that contributes
to uncontrolled muscle spasms, altered pain
responses, and threats to skin integrity;
alterations in bowel and bladder elimination; and
impaired sexual function.
