Transcript Guillain-Barré Syndrome, Myasthenia Gravis,

Guillain-Barré Syndrome,
Myasthenia Gravis,
Dr. Abdul-Monim Batiha
Guillain-Barré Syndrome
• is an acute inflammatory demyelinating
polyneuropathy (AIDP), a disorder affecting
the peripheral nervous system. It is usually
triggered by an acute infectious process. The
syndrome was named after the French
physicians Guillain, Barré and Strohl, who
were the first to describe it in 1916. It is
sometimes called Landry's paralysis, after the
French physician who first described a variant
of it in 1859. It is included in the wider group
of peripheral neuropathies.
ETIOLOGY
• The etiology of Guillain-Barré syndrome is
unclear, but an autoimmune response is
strongly suspected.
• There is a preceding event or trigger that is
often an infection.
• Occasionally, vaccinations have been known to
trigger Guillain-Barré syndrome.
• Approximately half of the people who develop
Guillain- Barré syndrome have a mild febrile
illness 2 to 3 weeks before the onset of
symptoms.
• The febrile infection is usually respiratory or
gastrointestinal.
• Approximately 25% of patients with this
disease have antibodies to either
cytomegalovirus or Epstein-Barr virus.
PATHOPHYSIOLOGY
• In Guillain-Barré syndrome, the myelin sheath
surrounding the axon is lost.
• Demyelination is a common response of
neural tissue to many agents and conditions,
including physical trauma, hypoxemia, toxic
chemicals, vascular insufficiency, and
immunological reactions.
• Loss of the myelin sheath in Guillain-Barré
syndrome makes nerve impulse transmission
is aborted.
CLINICAL MANIFESTATIONS
• The syndrome may develop rapidly over the
course of hours or days, or may take up to 3 to 4
weeks to develop.
• Most patients demonstrate the greatest
weakness in the first weeks of the disorder.
• Patients are at their weakest point by the third
week of the illness.
• In the beginning, a flaccid, ascending paralysis
develops quickly.
• The patient is most commonly affected in a
symmetrical pattern.
• The patient may first notice weakness in the
lower extremities that may quickly extend to
include weakness and abnormal sensations in
the arms.
• Deep tendon reflexes are usually lost, even in
the earliest stages.
• The trunk and cranial nerves may become
involved.
• Respiratory muscles can become affected,
resulting in respiratory compromise.
CLINICAL MANIFESTATIONS
• Autonomic disturbances such as urinary
retention and orthostatic hypotension may
also occur.
• Superficial and deep tendon reflexes may be
lost.
• Some patients experience tenderness and
pain on deep pressure or movement of some
muscles.
• Sensory symptoms of paresthesias, including
numbness and tingling, may occur.
• Pain is a complaint in a large number of
patients.
• It is aching in nature and often compared with
the feeling of muscles that have been
overexerted.
CLINICAL MANIFESTATIONS
• If there is cranial nerve involvement, cranial
nerve VII, the facial nerve, is most often
affected.
• Guillain-Barré syndrome does not affect level
of consciousness, pupillary function, or
cerebral function.
• Symptoms may progress for several weeks.
The level of paralysis may stop at any point.
• Motor function returns in a descending
fashion.
• Demyelination occurs rapidly, but the rate of
remyelination is approximately 1 to 2 mm per
day.
DIAGNOSIS
• The history of the onset of symptoms can be
revealing because symptoms of Guillain-Barré
syndrome usually begin with weakness or
paresthesias of the lower extremities and
ascend in a symmetrical pattern.
• A lumbar puncture may be performed and
reveal increased protein.
• Also, nerve conduction studies record impulse
transmission along the nerve fiber.
• Pulmonary function tests are done when
Guillain-Barré syndrome is suspected to
establish a baseline for comparison as the
disease progresses.
• Declining pulmonary function capacity may
indicate the need for mechanical ventilation
and management in an ICU.
CLINICAL MANAGEMENT
• preventive measures need to be established
to prevnt DVT and pulmonary embolism do
not develop.
• Heparin 5000 units subcutaneously may be
given along with antiembolism stockings and
sequential compression devices
• The first therapy proven to benefit patients
with Guillain-Barré syndrome is
plasmapheresis.
• This procedure mechanically removes humoral
factors.
• Intravenous immunoglobulin (IVIG) is also
useful in managing Guillain-Barré syndrome.
Myasthenia Gravis
• Myasthenia gravis (from Greek "muscle",
"weakness", and Latin gravis "serious";
abbreviated MG) is an autoimmune
neuromuscular disease leading to fluctuating
muscle weakness and fatigability. It is an
autoimmune disorder, in which weakness is
caused by circulating antibodies that block
acetylcholine receptors at the post-synaptic
neuromuscular junction, inhibiting the
stimulative effect of the neurotransmitter
acetylcholine.
ETIOLOGY
• Myasthenia gravis is an autoimmune disorder.
• The factors that trigger the autoimmune
process are not known, but the thymus gland
is involved.
• The thymus lies behind the sternum and may
extend down to the diaphragm or up to the
neck.
• This gland plays a role in the responsiveness of
T cells to foreign antigens.
• The thymus gland is large in children and
small in adults.
• By adulthood, the gland has shrunken and has
nearly been replaced by fat.
• Abnormalities in the thymus gland frequently
occur in patients with myasthenia gravis.
• Eighty percent of patients with myasthenia
gravis have thymal hyperplasia.
PATHOPHYSIOLOGY
• Myasthenia gravis is a result of circulating
antibodies directed toward the skeletal muscle
acetylcholine receptors.
• This leads to a decrease in end plate
depolarization, which may be insufficient to
generate an action potential.
• This results in a failure of the muscle to
contract.
CLINICAL MANIFESTATIONS
• The hallmark of myasthenia gravis is
fatigability. Muscles become progressively
weaker during periods of activity and improve
after periods of rest. Muscles that control eye
and eyelid movement, facial expressions,
chewing, talking, and swallowing are
especially susceptible.
• The muscles that control breathing and neck
and limb movements can also be affected.
• Symptoms, which vary in type and severity,
may include asymmetrical ptosis (a drooping
of one or both eyelids), diplopia (double
vision) due to weakness of the muscles that
control eye movements, an unstable or
waddling gait, weakness in arms, hands,
fingers, legs, and neck, a change in facial
expression, dysphagia (difficulty in
swallowing), shortness of breath and
dysarthria (impaired speech).
• In myasthenic crisis a paralysis of the
respiratory muscles occurs, necessitating
assisted ventilation to sustain life. In patients
whose respiratory muscles are already weak,
crises may be triggered by infection, fever, an
adverse reaction to medication, or emotional
stress. Since the heart muscle is only
regulated by the autonomic nervous system, it
is generally unaffected by MG.
DIAGNOSIS
• patient’s history
• Patients may present with complaints of double
vision or drooping eyelids.
• Also, myasthenia gravis causes weakness of the
shoulder girdle muscles.
• The cranial nerve examination may reveal
ptosis and diplopia
• Motor weakness may be exhibited
• Blood is drawn for acetylcholine receptor
antibodies
• Electromyography (EMG)
CLINICAL MANAGEMENT
• The clinical management of myasthenia gravis
includes the following strategies:
1. use of medications to enhance
neuromuscular transmission; such as
anticholinesterases (Pyridostigmine
(Mestinon), and steroids (Prednisone)
• long-term immunosuppression with
corticosteroids, azathioprine (Imuran),
cyclophosphamide (Cytoxan), or cyclosporine;
• short-term immunomodulation with
plasmapheresis or IVIG; or thymectomy.