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Guillain-Barré Syndrome (GBS)
(Acute Idiopathic Polyneuritis; Acute Inflammatory Demyelinating Polyradiculoneuropathy)
Guillain-Barré syndrome is an acute, usually rapidly progressive but self-limited inflammatory polyneuropathy characterized by muscular weakness and mild distal sensory loss. Cause is thought to be autoimmune. Diagnosis is clinical. Treatment includes IV immune globulin, plasma exchange, and, for severe cases, mechanical ventilation.
Guillain-Barré syndrome is the most common acquired inflammatory neuropathy. Although the cause is not fully understood, it is thought to be autoimmune. There are several variants. In some, demyelination predominates; others affect the axon.
In about two thirds of patients, the syndrome begins 5 days to 3 wk after a banal infectious disorder, surgery, or vaccination. Infection is the trigger in > 50% of patients; common pathogens include Campylobacter jejuni , enteric viruses, herpesviruses (including cytomegalovirus and Epstein-Barr virus), and Mycoplasma sp. A cluster of cases followed the swine flu vaccination program in 1976, but the association was later shown to be spurious, due to ascertainment bias.
Flaccid weakness predominates in most patients; it is always more prominent than sensory abnormalities and may be most prominent proximally. Relatively symmetric weakness with paresthesias usually begins in the legs and progresses to the arms, but it occasionally begins in the arms or head. In 90% of patients, weakness is maximal at 3 wk. Deep tendon reflexes are lost. Sphincters are usually spared. Facial and oropharyngeal muscles are weak in > 50% of patients with severe disease. Dehydration and undernutrition may result. Respiratory paralysis severe enough to require endotracheal intubation and mechanical ventilation occurs in 5 to 10%.
A few patients (possibly with a variant form) have significant, life-threatening autonomic dysfunction causing BP fluctuations, inappropriate ADH secretion, cardiac arrhythmias, GI stasis, urinary retention, and pupillary changes. An unusual variant (Fisher variant) may cause only ophthalmoparesis, ataxia, and areflexia.
Diagnosis is primarily clinical. Similar acute weakness can result from myasthenia gravis, botulism, poliomyelitis (mainly outside the US), tick paralysis, West Nile virus infection, and metabolic neuropathies, but these disorders can usually be distinguished as follows:
Myasthenia gravis is intermittent and worsened by exertion.
Botulism may cause fixed dilated pupils (in 50%) and prominent cranial nerve dysfunction with normal sensation.
Poliomyelitis usually occurs in epidemics.
Tick paralysis causes ascending paralysis but spares sensation.
West Nile virus causes headache, fever, and asymmetric flaccid paralysis but spares sensation.
Metabolic neuropathies occur with a chronic metabolic disorder.
Tests for infectious disorders and immune dysfunction, including tests for hepatitis and HIV and serum protein electrophoresis, are done.
If Guillain-Barré syndrome is suspected, patients should be admitted to a hospital for electrodiagnostic testing (nerve conduction studies and electromyography), CSF analysis, and monitoring by measuring forced vital capacity every 6 to 8 h. Initial electrodiagnostic testing detects slow nerve conduction velocities and evidence of segmental demyelination in two thirds of patients; however, normal results do not exclude the diagnosis and should not delay treatment.
CSF analysis may detect albuminocytologic dissociation (increased protein but normal WBC count), but it may not appear for up to 1 wk and does not develop in 10% of patients.
Rarely, cervical spinal cord compression—particularly when polyneuropathy coexists (causing or contributing to hyporeflexia) and bulbar involvement is not prominent—may mimic Guillain-Barré syndrome; in such cases, MRI should be done.
This syndrome is fatal in < 2%. Most patients improve considerably over a period of months, but about 30% of adults and even more children have some residual weakness at 3 yr. Patients with residual defects may require retraining, orthopedic appliances, or surgery.
After initial improvement, 3 to 10% of patients develop chronic inflammatory demyelinating polyneuropathy (CIDP—see Chronic Inflammatory Demyelinating Polyneuropathy).
Guillain-Barré syndrome is a medical emergency, requiring constant monitoring and support of vital functions, typically in an ICU. Forced vital capacity should be measured frequently so that respiration can be assisted if necessary; if vital capacity is < 15 mL/kg, endotracheal intubation is indicated. Inability to lift the head off the pillow by flexing the neck is another danger sign; it frequently develops simultaneously with phrenic nerve (diaphragm) weakness.
If oral fluid intake is difficult, IV fluids are given as needed to maintain a urine volume of at least 1 to 1.5 L/day. Extremities should be protected from trauma and from the pressure of bed rest. Heat therapy helps relieve pain, making early physical therapy possible. Immobilization, which may cause ankylosis and contractures, should be avoided. Passive full-range joint movement should be started immediately, and active exercises should be initiated when acute symptoms subside. Heparin 5000 units sc bid helps prevent deep venous thrombosis in bedbound patients.
Given early, IVIG 400 mg/kg IV once/day for 5 consecutive days is the treatment of choice; it has some benefit up to 1 mo from disease onset.
Plasma exchange (see Plasma exchange) helps when done early; it is used if IVIG is ineffective. Plasma exchange is relatively safe, shortens the disease course and hospital stay, and reduces mortality risk and incidence of permanent paralysis. Plasma exchange removes any previously administered IVIG, negating its benefits, and so should never be done during or soon after use of IVIG. Waiting at least 2 to 3 days after stopping IVIG is recommended.
Corticosteroids do not improve and may worsen the outcome.
Guillain-Barré syndrome typically begins with an ascending, relatively symmetric flaccid weakness.
Initially, distinguish other disorders that cause similar symptoms (eg, myasthenia gravis, botulism, tick paralysis, West Nile virus infection, metabolic neuropathies; outside the US, poliomyelitis) based on history and examination results.
Do electrodiagnostic testing and usually CSF analysis, even though diagnosis is primarily clinical.
About 70% of patients recover completely, but 3 to 10% develop chronic inflammatory demyelinating polyneuropathy.
Intensive supportive care is key to recovery.
Try IVIG first, then if it is ineffective, plasma exchange.
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