Neuromuscular Disorders
Part 3
Presented by F. Briggs MS, APRN-C
January 13, 2010
January Intersession
Myasthenia Gravis
• A neuromuscular disorder in which there is
a disturbance in the transmission of
impulses from nerve to muscle cells at the
neuromuscular junction, causing extreme
muscle weakness
• Most commonly occurs bet, ages of 10
and 65. Peaks age of onset in women is
20-30 years, and over 40 for men
Myasthenia Con’t
• Ninety percent of cases show eyelid
muscles or extraocular muscle
involvement. Facial mobility and
expression can be impaired, and
there may be difficulty w/chewing and
swallowing. Speech can also be
affected and when prolonged-voice
fades.
Etiology
• Autoimmune disorder whereby antibodies
destroy acetylcholine receptor sites on the postsynaptic membrane of the neuromuscular
junction, resulting in a decreased number of
ACh receptor sites at neuromuscular junction.
This prevents ACh molecules from attaching
and stimulating muscle contractions.
• Anti-ACh receptors are detectable in 85-90% of
patients with generalized MG and in 50-60% of
patient’s with ocular MG (most common in men)
Signs and Symptoms
• Diplopia, dysphagia
• Extreme muscle weakness, increased with
activity and reduced with rest
• Ptosis, mask like facial expression
• Difficulty with feeding and chewing
• Weak voice, hoarseness
• *There is no sensory loss, reflexes are
normal, and muscle atrophy is rare
Diagnosis of Myasthenia Gravis
• Tensilon test- IV injection of Tensilon
provides spontaneous relief of symptoms
(last 5-10minutes)-increased muscle
contractility
• Electromyelography (EMG)- amplitude of
evoked potential decreases with repeated
tests
• Presence of Anti-acetylcholine receptor
antibodies in the serum is present in 8590% of cases
Crisis
• Myasthenic- Exacerbation of myasthenia
following precipitating factors of failure to
take drug as prescribed or drug dose too
low.
• Cholinergic- Overdose of
anticholinesterase drugs resulting in
increased Ach at the receptor sites,
remission is spontaneous or after
thymectomy
Medical Management
• Drug therapy- anticholinesterase drugsambenonium (Mytelase), neostigmine
(Prostigmine), and Pyridostigmine (Mestinon)
• These drugs act by blocking the action of
cholinesterase and increases the levels of
acetylcholine at the neuromuscular junction
• SE’s- excessive salivation and sweating, N/V/D,
fasciculations (twitching)
• Corticosteroids- Prednisone- used if other drugs
are not effective
• Suppress the autoimmune response
Surgery
• Thymectomy- surgical removal of the thymus
gland-thought to be involved in the production
of acetylcholine receptor antibodies. Indicated
in all patients w/Thymoma, generalized MG
between ages of puberty and 65, and for
patients with purely ocular MG.
*May cause remission in some clients especially
if performed early in the disease
• Plasma exchange (Plasmaphoresis)- removes
circulating acethylcholine receptor antibodies
• Use in clients who don’t respond to other
therapies
Nursing Considerations
• Give medication exactly on time
• Give with milk and crackers to decrease SE’s
• Monitor effectiveness of drugs by assessing
muscle strength and vital capacity before and
after medication
• Avoid using morphine and strong sedatives,
quinine, TCA’s Lithium carbonate, Benzo’s,
aminoglycosides -gentamycin, neomycin,
streptomycin- skeletal muscle blocking effect
Nsg. Considerations con’t
• Promote optimal nutrition- mealtimes should
coincide w/ effects of drugs- give medications at
least 30min before meal
• Check gag reflex and ability to swallow
• Provide soft mechanical diet
• If patient has difficulty eating/swallowing-keep
emergency equipment nearby
• Monitor respiratory status frequently, plans to
take advantage of energy peaks and provide
frequent rest periods
Bell’s Palsy
• Is a form of temporary facial paralysis
resulting from damage or trauma to one of
the two facial nerves. The facial nerve
also called the 7th cranial nerve-is a paired
nerve that travels through a narrow, bony
canal (called the fallopian canal) in the
skull, beneath the ear, to the muscles of
the side of the face.
Bell’s Palsy con’t
• Each facial nerve directs the muscles on
one side of the face, including those that
control eye blinking and closing, and facial
expressions such as smiling and frowning.
• In addition, it carries nerve impulses to the
lacrimal (tear glands), the saliva glands,
and to the muscles of the middle ear
bone-called the stapes.
• It also transmits taste sensations from the
tongue
What Causes Bell’s Palsy?
• Bell’s palsy occurs when the nerve that
controls the facial muscles is swollen,
inflamed, or compressed, resulting in
facial weakness or paralysis. However,
what exactly causes this damage, is
unknown.
• There has been a viral link- Viral
meningitis or the common cold, HSV1,2,
HHV, CMV, Adenovirus, Hep. A,B, and C,
Rubella, and Influenza virus
Who Get’s Bell’s Palsy?
• Bell’s palsy afflicts approximately 40,000
Americans each year. It affects men and
women equally and can occur at any age, but is
less common in children less than 15years old
and in adults over age 60.
• Peak incidence is between the age of 15-45y/o.
Also, increased incidence in people of
Japanese descent.
• Disproportionately affects people with diabetes,
women who are pregnant, and people with URI
such as cold or Flu.
Symptoms of Bell’s Palsy
• Symptoms of bell’s palsy vary from person
to person and range in severity from mild
weakness to total paralysis. More
importantly, symptoms occur suddenly
and peak within 48hours.
• May include twitching, weakness or
paralysis on one or both sides of the face
• Drooping of the eyelid and corner of the
mouth
Symptoms Con’t
• Drooling, loss of taste, impaired speech
• Dryness of the eye or mouth
• Headache, ringing in the ears, increased
sensitivity to normal sounds (Hyperacusis)
• Impairment in taste and excessive tearing
of the eye (Epiphora)
• Dizziness
• Difficulty eating or drinking
Differential Diagnosis
•
•
•
•
•
Stroke
Tumors
Other Infections- such as Meningitis
Trauma
Other neurological diseases such as Multiple
Sclerosis
• **The physical exam and symptoms are the
most important part of making a diagnosis of
Bell’s Palsy
Treatment
• There is no standard treatment, some
controversy over the use of steroids, but if
used, recommended to start early.
Recommended dosage is 1mg/kg/d PO for
7days.
• Use of Acyclovir or Valacyclovir (antiviral has
been used)- normal adult dose 4,000mg/24hr
PO for 7-10days. In children >2y/o- 1,000mg
PO QID for 10 days. If Lyme’s disease
suspected- use Abx like Doxycycline
• Use of analgesics (Aspirin, Tylenol, or Motrin)
Other Treatments
• Another important factor is eye protectionuse of artificial tears, lubricants, and eye
protection
• Physical therapy to stimulate the facial
nerve, including massage to prevent
permanent contractures
• Moist heat to reduce pain on the affected
side
• Vit. B12, B6, and Zinc which help nerve
growth
Treatments con’t
• Based on severity of symptoms-some
people require surgery for nerve
decompression
• Remember- 85-90% recover with no
permanent damage, 10-15%- experience
incomplete recovery of nerve function, but
no cosmetic effects (i.e., twisted mouth)
• 5-10% experience permanent neurological
sequelae that are cosmetically and
clinically apparent
Prognosis
• Bell’s Palsy usually goes away by itself without
treatment. The extent of nerve damage
determines the extent of recovery.
• Most people begin to recover within 2-3weeks,
with 70-85% of the people showing complete
recovery in 2-3months.
• There is a 10% recurrence rate. Those who are
at highest risk of not getting better are often
older and those who have a slower recovery
from symptoms.
• Complete recovery is expected within 36months
Guillain’ Barre Syndrome
• Ghee-yan-Bah-ray syndrome also called acute
inflammatory demyelinating
polyradiculoneuropathy and Landry’s ascending
paralysis, is a life threatening inflammatory
disorder of the peripheral nervous systemaffects the peripheral nerves (i.e., those outside
the brain and spinal cord).
• GBS is the most common cause of rapidly
acquired paralysis in the United States today,
affecting 1-3 people in every 100,000
Etiology of GBS
• The disorder came to public attention briefly when it
struck a number of people who received the 1976
Swine Flu vaccine.
• The true cause of GBS is not known and there is no
effective treatment. Approx. 50% of the cases occur
shortly after a microbial (viral or bacterial) infection
such as a sore throat, or diarrhea have cleared up.
• Some theorize an autoimmune mechanism, in
which the patient’s defense system of antibodies and
WBC’s are triggered into damaging the nerve
covering or insulation (i.e., myelin sheath) leading
to weakness and abnormal sensation.
Etiology Con’t
• According to Kumar, Abbas, and Fausto (2005),
Infections with campylobacter jejuni,
cytomegalovirus, Epstein barr-Virus, and
Mycoplasma Pneumoniae have been shown to
have a significant epidemiological association
with GBS.
• Segmental demyelination affecting peripheral
nerves is the primary lesion, but damage to
axons is also characteristic, particularly when
the disease is severe.
GBS Signs and Symptoms
• A rapid onset of ascending weakness,
frequently associated with abnormal sensations
that affect both sides of the body similarly-is a
common presenting symptom
• It typically begins w/weakness and/or abnormal
sensations of the legs and arms (from distal to
proximal). It can also affect muscles of the
chest, face, and eyes. Although many cases are
mild, some patients are virtually paralyzed.
Breathing may require the use of a ventilator.
• Loss of reflexes, such as knee jerk, are often
found.
Diagnosis/Treatment of Guillain
Barre-Syndrome
• Basically made on the presenting symptoms, but
to confirm a diagnosis, a Lumbar Puncture is
done and should show elevated fluid protein and
an Electromyography (electrical test of the nerve
and muscle) may be done.
• Initial focus is to maintain airway and monitor
other body functions
• Plasma exchange ( a blood cleansing procedure)
and high dose intravenous immune globulins
(which help to neutralize the antibodies by
attaching to them) are often helpful to shorten the
course of GBS.