Pulmonary Medicine

Neuromuscular Disorders Affecting the Thorax: Guillain-Barre Syndrome

What every physician needs to know:

Guillain-Barre syndrome (GBS), or acute idiopathic polyneuritis, is characterized by ascending symmetric paralysis. Respiratory involvement may be absent, or it may be severe enough to necessitate mechanical ventilation. Seventy percent of cases are preceded by viral or bacterial infection. The incidence of GBS worldwide ranges from 1.1 per 100,000 persons per year to1.8 per 100,000 persons per year. Among those older than age fifty, the incidence increases to between 1.7 and 3.3 per 100,000 persons per year.

Classification

Not applicable.

Are you sure the patient has Guillain-Barre syndrome? What should you expect to find?

Clinical findings in GBS include weakness associated with absent tendon reflexes and autonomic dysfunction from mild paresis to complete paralysis. Half of patients reach their maximum level of weakness within 2 weeks of onset, and 80% do so within 4 weeks. Ten percent of patients may have weakness beginning in the upper extremities, rather than the classic ascending paralysis. Facial (in 60%), oropharyngeal (in 50%), or ocular (in 15%) involvement may occur. The presence of sensory loss is variable, occurring in 40-70% of patients; paresthesias occasionally accompany the sensory findings.

Nasal voice (because of palatal incontinence), abnormal gag reflex, dysarthria, or inability to sip water without coughing are additional findings. Severe back pain may be noted, and autonomic dysfunction, observed in 65% of patients, is evident as cardiac arrhythmias, blood pressure liability, gastrointestinal dysfunction, pupillary dysfunction, and urinary retention. Fifteen to 30% of patients develop respiratory failure requiring mechanical ventilation, the average duration of which is 50 to 55 days, with most requiring tracheostomy.

Diagnostic criteria include features required for making the diagnosis and those supportive of the diagnosis. Features required for the diagnosis are progressive weakness of more than one limb, accompanied by areflexia. Weakness may involve only the lower extremities, with hyporeflexia noted elsewhere. Features supportive of the diagnosis are symptom progression over days or weeks, relative symmetry of findings, mild sensory findings, autonomic dysfunction, and absence of fever at the time of presentation. An elevation in cerebrospinal fluid (CSF) protein and characteristic electrodiagnostic studies support the clinical findings. Antibody testing may also be useful.

An alternative diagnosis should be considered when the CSF cell count exceeds 10/mm3, a sensory level is present, asymmetric weakness persists, or severe, persistent bowel or bladder dysfunction is noted.

Beware: there are other diseases that mimic Guillain-Barre syndrome.

The neurologic disorders that may be confused with GBS include vasculitis with mononeuritis multiplex, Lyme disease, arsenic poisoning, tick paralysis, porphyria, sarcoidosis, leptomeningeal disease, paraneoplastic disease, critical illness myopathy/neuropathy, chronic inflammatory demyelinating polyneuropathy, spinal cord compression, acute transverse myelitis, myasthenia gravis, Lambert-Eaton myasthenic syndrome, botulism, and polymyositis.

How and/or why did the patient develop Guillain-Barre syndrome?

The etiology of GBS is unknown. Risk factors include: viral illnesses, including cytomegalovirus and Epstein-Barr virus infections; infection with Mycoplasma pneumoniae or Campylobacter jejuni; influenza vaccination; recent surgery; and lymphoma.

GBS may be an autoimmune disease, with an aberrant immune response directed against bacterial lipopolysaccharides and epitopes similar to the myelin sheath or Schwann cell basement membrane. Possible links between vaccinations and GBS have been proposed although the evidence is weak.

Which individuals are at greatest risk of developing Guillain-Barre syndrome?

See risk factors above.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

CSF studies are characterized by elevated protein and few cells--so-called albumino-cytologic dissociation--which is found in 90% of patients after one week of symptoms.

Testing for antibodies directed at a ganglioside component of nerve (anti-GQ1b) may be used to distinguish Miller-Fisher syndrome, a GBS variant, since 85% of patients with Miller-Fisher syndrome have anti-GQ1b antibodies.

What imaging studies will be helpful in making or excluding the diagnosis of Guillain-Barre syndrome?

Not applicable.

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of Guillain-Barre syndrome?

Not applicable.

What diagnostic procedures will be helpful in making or excluding the diagnosis of Guillain-Barre syndrome?

A diagnosis of GBS is supported by electromyography (EMG) and nerve conduction studies.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of Guillain-Barre syndrome?

Not applicable.

If you decide the patient has Guillain-Barre syndrome, how should the patient be managed?

Consideration should be given to three general areas: supportive care, therapy directed at the underlying disease process, and emergency management.

Supportive Care

Respiratory management focuses on avoiding pulmonary complications and providing timely implementation of mechanical ventilation. Neurophysiologic testing helps predict the need for mechanical ventilation, as a demyelinating pattern is associated with a greater need for intubation than an axonal pattern or equivocal findings. Serial vital capacity measurements may also be useful in predicting the need for mechanical ventilation, as a VC of 12-15 mg/kg is a sign of imminent respiratory failure. VC averages 33% of predicted at the time of intubation.

Other predictors of the need for intubation include fewer than seven days between symptom onset and hospitalization, an inability to lift the head, bulbar dysfunction, and the presence of anti-GQ1b antibodies. Tracheostomy should be considered after two weeks if no improvement in pulmonary function is noted. During the recovery phase, weaning trials should be considered when the VC exceeds 8-10 ml/kg, adequate oxygenation is achieved using an FiO2 less than 40%, and the patient is able to double the minute ventilation and generate a negative inspiratory force greater than -40 cmH2O.

Autonomic dysfunction warrants close monitoring.

Cardiovascular management includes stabilization of blood pressure (sometimes necessitating an arterial line), treatment of hypotension with intravenous fluids or pressors (e.g., phenylephrine), treatment of hypertension (e.g., using labetalol, esmolol, or nitroprusside), and monitoring for and correction of arrhythmias. Sinus tachycardia, which is common in GBS, requires no treatment.

Bowel and bladder function must be monitored closely.

Pain control is an important aspect of management. Opiate use should be limited, although gabapentin, carbamazepine, and nonsteroidal anti-inflammatory drugs may be helpful. Use of DVT prophylaxis is critical.

Incorporation of rehabilitation services early in the patient's course is encouraged as well.

Therapy Directed at the Underlying Disease Process

Plasmapheresis plays a central role in management of GBS. Plasmapheresis is most effective if it is started within seven days of symptom onset; however, improvement can be demonstrated with initiation of plasmapheresis started within thirty days. Plasmapheresis (with albumin or fresh frozen plasma) given at a dose of 250 mL/kg every two days for a total of five treatments produces short-term benefits, promotes early motor recovery and ambulation, and results in a decrease in the need for mechanical ventilation. 10% of patients may relapse after plasmapheresis because of antibody rebound.

Use of intravenous immunoglobulin (IVIG) is preferable to plasma exchange, as it is easier to administer. IVIG (0.4 g/kg/day for five days), begun within two weeks of disease onset, may be as effective as plasmapheresis. Contraindications to the use of IVIG include low serum IgA level, uncontrolled hypertension, and a hyperosmolar state. No benefit has been demonstrated with giving IVIG following plasmapheresis compared with administration of each therapy alone.

Administration of corticosteroids alone has not been demonstrated to be of benefit. While use of corticosteroids may slow recovery, administration of corticosteroids in addition to IVIG may hasten recovery, although no long-term data are available.

For particularly refractory cases, use of interferon-beta may be beneficial.

Emergency Management

For respiratory emergencies, guidelines for intubation include a VC less than 12-15 mg/kg, refractory hypoxemia, hypercapnia, or an inability to clear oral secretions. Succinylcholine should be avoided during intubation, as its use in this population has been associated with development of rapid hyperkalemia and subsequent life-threatening arrhythmias. Delayed intubation in those with bulbar dysfunction increases the risk of early pneumonia.

For cardiac emergencies, observation for arrhythmias with intubation and suctioning to address autonomic dysfunction is important. Tachyarrhythmias, bradyarrhythmias, or asystole may occur.

What is the prognosis for patients managed in recommended ways?

The prognosis for recovery from GBS is usually good. Common complications include pneumonia, recurrent aspiration, and pulmonary embolism. 85% of patients have residual neurologic sequelae. Mortality decreased from 15% in the 1970s to fewer than 4% by 1980.

A poor prognosis is associated with older age, lower (less than 20% of normal) mean compound muscle action potential amplitudes during distal nerve stimulation, need for ventilatory support, and rapid progression to severe weakness (less than one week).

What other considerations exist for patients with Guillain-Barre syndrome?

10% of patients can have relapses with increased weakness. Treatment related fluctuation is the term utilized for patients who do well after initial therapy but then have a deterioration of their condition.

Up to 5% of patients initially diagnosed with GBS will develop chronic inflammatory polyradiculopathy.

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