USMLE Forum Archives - USMLE Step 3 - GUILLAIN-BARRÉ SYNDROME (GBS)
GUILLAIN-BARRÉ SYNDROME (GBS)
meduploader - 05-15-09 10:00
A postinfectious autoimmune acute demyelinating polyneuropathy. Given the decline of polio, it is
now the most common cause of acute flaccid paralysis. GBS classically follows an acute GI illness
caused by Campylobacter jejuni, as antibodies directed toward its bacterial lipopolysaccharide cross-react
with peripheral nerve myelin; other infections (e.g., HIV, Mycoplasma) have also been associated with
GBS.
Symptoms such as back pain or lower extremity paresthesias typically begin 1–2 weeks after the
infection, followed by symmetric weakness that begins in the feet and gradually ascends over hours to
days. Weakness severity can range from mild to complete quadriplegia with respiratory failure.
Autonomic symptoms are prominent, and cardiac instability can be life-threatening. Despite sensory
symptoms (paresthesias), the sensory examination is often normal.
A unique variant, Miller-Fisher syndrome, produces symptoms of ophthalmoplegia, ataxia, and areflexia,
with little weakness of the extremities.
Overall, GBS is a monophasic disease, with maximal symptoms seen by four weeks.
Cardinal features on exam are areflexia and symmetric progressive weakness.
Best Initial test: lumbar puncture for protein and cell count
CSF shows “albuminocytologic dissociation”—isolated elevated protein with normal WBC counts.
Miller-Fisher syndrome is associated with anti-GQ1b antibodies.
Most Accurate test: Electromyography (EMG)
NCS reveals demyelinating changes of the proximal peripheral nerves.
Serial PFTs with maximum inspiratory force and FVC are important for following diaphragmatic
function, which often portends ventilatory failure.
TREATMENT
Standard treatment is either IVIG or plasmapheresis; steroids are not beneficial.
Indications for plasmaphresis:
Severe flaccid paralysis, bulbar palsy, progressive repiratory failureand patients on mechanical
ventilation.
It is most effective when it is started within seven days of the onset of symptoms.
Plasmaphresis is not usually indicated for ambulatory patients with mild or non progressive disease.
Daily administration of IVIG for two weeks may also be used to treat patients with GBS because it has
shown to be effective as plasmaphresis.
Mechanical ventilation should be considered when FVC falls to 15 mL/kg. Do not wait for PCO2 to rise.
Keep patients with autonomic symptoms on cardiac telemetry.
In Guillain-Barré syndrome, rapid progression to respiratory failure can occur within hours.
Therefore, a timely and accurate diagnosis is critical.
If you suspect Guillain-Barré syndrome, immediately admit the patient to the hospital regardless of the
severity of the illness. Measurements of bedside vital capacity provide the most useful information
regarding the degree of respiratory impairment. Patients with signs of respiratory failure should be
promptly itubated and supported with mechanicial ventilation until the resolution of respratory muscle
weakness.
Signs of recovery within 1 to 3 weeks after onset favors a good prognosis. If illness continues for a longer
period (e.g., beyond 6 weeks), a chronic relapsing course is more likely and prognosis is less favorable.
It may take months before the patient recovers. A minority of patients experience recurrent attacks, and
about 5% die due to respiratory failure, pneumonia, or arrhythmias.
meduploader - 05-15-09 10:00
A postinfectious autoimmune acute demyelinating polyneuropathy. Given the decline of polio, it is
now the most common cause of acute flaccid paralysis. GBS classically follows an acute GI illness
caused by Campylobacter jejuni, as antibodies directed toward its bacterial lipopolysaccharide cross-react
with peripheral nerve myelin; other infections (e.g., HIV, Mycoplasma) have also been associated with
GBS.
Symptoms such as back pain or lower extremity paresthesias typically begin 1–2 weeks after the
infection, followed by symmetric weakness that begins in the feet and gradually ascends over hours to
days. Weakness severity can range from mild to complete quadriplegia with respiratory failure.
Autonomic symptoms are prominent, and cardiac instability can be life-threatening. Despite sensory
symptoms (paresthesias), the sensory examination is often normal.
A unique variant, Miller-Fisher syndrome, produces symptoms of ophthalmoplegia, ataxia, and areflexia,
with little weakness of the extremities.
Overall, GBS is a monophasic disease, with maximal symptoms seen by four weeks.
Cardinal features on exam are areflexia and symmetric progressive weakness.
Best Initial test: lumbar puncture for protein and cell count
CSF shows “albuminocytologic dissociation”—isolated elevated protein with normal WBC counts.
Miller-Fisher syndrome is associated with anti-GQ1b antibodies.
Most Accurate test: Electromyography (EMG)
NCS reveals demyelinating changes of the proximal peripheral nerves.
Serial PFTs with maximum inspiratory force and FVC are important for following diaphragmatic
function, which often portends ventilatory failure.
TREATMENT
Standard treatment is either IVIG or plasmapheresis; steroids are not beneficial.
Indications for plasmaphresis:
Severe flaccid paralysis, bulbar palsy, progressive repiratory failureand patients on mechanical
ventilation.
It is most effective when it is started within seven days of the onset of symptoms.
Plasmaphresis is not usually indicated for ambulatory patients with mild or non progressive disease.
Daily administration of IVIG for two weeks may also be used to treat patients with GBS because it has
shown to be effective as plasmaphresis.
Mechanical ventilation should be considered when FVC falls to 15 mL/kg. Do not wait for PCO2 to rise.
Keep patients with autonomic symptoms on cardiac telemetry.
In Guillain-Barré syndrome, rapid progression to respiratory failure can occur within hours.
Therefore, a timely and accurate diagnosis is critical.
If you suspect Guillain-Barré syndrome, immediately admit the patient to the hospital regardless of the
severity of the illness. Measurements of bedside vital capacity provide the most useful information
regarding the degree of respiratory impairment. Patients with signs of respiratory failure should be
promptly itubated and supported with mechanicial ventilation until the resolution of respratory muscle
weakness.
Signs of recovery within 1 to 3 weeks after onset favors a good prognosis. If illness continues for a longer
period (e.g., beyond 6 weeks), a chronic relapsing course is more likely and prognosis is less favorable.
It may take months before the patient recovers. A minority of patients experience recurrent attacks, and
about 5% die due to respiratory failure, pneumonia, or arrhythmias.
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Re: GUILLAIN-BARRÉ SYNDROME ( mtniharika - 09-28-09 02:19 really exhaustive but just to add.
CLINICAL VARIANTS:
Six different subtypes of Guillain-Barre syndrome (GBS) exist:
1.Acute inflammatory demyelinating polyneuropathy (AIDP) is the most common form of GBS, and the term is often used synonymously with GBS. It is caused by an auto-immune response directed against Schwann cell membranes.
2.Miller–Fisher syndrome (MFS) is a rare variant of GBS and manifests as a descending paralysis, proceeding in the reverse order of the more common form of GBS. It usually affects the eye muscles first and presents with the triad of ophthalmoplegia, ataxia, and areflexia. Anti-GQ1b antibodies are present in 90% of cases.
3.Acute motor axonal neuropathy (AMAN), Chinese Paralytic Syndrome, attacks motor nodes of Ranvier and is prevalent in China and Mexico. It is likely due to an auto-immune response directed against the axoplasm of peripheral nerves. The disease may be seasonal and recovery can be rapid. Anti-GD1a antibodies are present. Anti-GD3 antibodies are found more frequently in AMAN.
4.Acute motor sensory axonal neuropathy (AMSAN) is similar to AMAN but also affects sensory nerves with severe axonal damage. Like AMAN, it is likely due to an auto-immune response directed against the axoplasm of peripheral nerves. Recovery is slow and often incomplete.
5.Acute panautonomic neuropathy is the most rare variant of GBS, sometimes accompanied by encephalopathy. It is associated with a high mortality rate, due to cardiovascular involvement, and associated dysrhythmias. Impaired sweating, lack of tear formation, photophobia, dryness of nasal and oral mucosa, itching and peeling of skin, nausea, dysphagia, constipation unrelieved by laxatives or alternating with diarrhea occur frequently in this patient group. Initial nonspecific symptoms of lethargy, fatigue, headache, and decreased initiative are followed by autonomic symptoms including orthostatic lightheadedness, blurring of vision, abdominal pain, diarrhea, dryness of eyes, and disturbed micturition. The most common symptoms at onset are related to orthostatic intolerance, as well as gastrointestinal and sudomotor dysfunction.Parasympathetic impairment (abdominal pain, vomiting, obstipation, ileus, urinary retention, dilated unreactive pupils, loss of accommodation) may also be observed.
6.Bickerstaff’s brainstem encephalitis (BBE), is further variant of Guillain-Barré syndrome. It is characterized by acute onset of ophthalmoplegia, ataxia, disturbance of consciousness, hyperreflexia or Babinski’s sign. The course of the disease can be monophasic or remitting-relapsing. Large, irregular hyperintense lesions located mainly in the brainstem, especially in the pons, midbrain and medulla are described in the literature. BBE despite severe initial presentation usually has a good prognosis. MRI plays a critical role in the diagnosis of BBE.
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