GUILLAIN-BARRÉ SYNDROME (GBS)

GUILLAIN-BARRÉ SYNDROME (GBS)

A 46-year-old man is brought to your office complaining of “rubbery legs.” The patient states that his symptoms began 2 days ago and that approximately 3 weeks ago, he experienced several episodes of diarrhea, which resolved spontaneously. On neurologic examination, bilateral lower-extremity weakness and a loss of reflexes are noted.

Definition. An acute, often severe polyradiculopathy whose underlying pathophysiology is an autoimmune destruction of  myelin.

Etiology. Evidence suggests that GBS is caused by a misdirection of the immune response, where the body’s immune system attacks self-antigens mistaken for foreign antigens (molecu- lar mimicry).

Clinical Presentation. Most patients will present with rapidly developing weakness that typi- cally begins in the lower extremities and moves upward. On physical examination the patient is noted to lack reflexes in the muscle groups affected. The progression of the symptoms will develop over the course of hours to days. The legs are usually more affected than the arms and face. Fever, constitutional symptoms, or bladder dysfunction are rare and should raise the possibilities of alternate diagnoses.

In addition to the motor weakness, patients will typically complain of sensory disturbances that can take the form of pain or tingling dysesthesia. Sensory changes are due to loss of large sensory fibers, producing loss of reflexes and proprioception. Autonomic instability (profuse sweating, postural hypotension, labile blood pressure, cardiac dysrhythmias) occurs in severe GBS, requiring patient treatment in an intensive care unit.

Approximately 75% of patients who present with GBS will have a history of an infection    1 to 3 weeks preceding the onset of symptoms.  The infection is typically in the respira-  tory or gastrointestinal systems (Campylobacter jejuni), although GBS may be preceded by infections with human herpesvirus, cytomegalovirus, or the Epstein-Barr virus. The only association between immunizations and GBS occurred in 1976 with the introduction of the swine influenza vaccine. More recent formulations of influenza vaccine are associated with one case of GBS per million patients immunized. GBS occurs more frequently in patients with HIV, systemic lupus erythematous, and  lymphoma.

Diagnosis. Diagnosis lies principally in recognizing the typical pattern of weakness with the absence of reflexes, fever, and constitutional symptoms. A lumbar puncture for protein and cell count is always the best initial test. The characteristic finding is an elevated protein without an associate rise in the cell count on CSF. These changes in the cerebral spinal fluid do not occur until 48 hours after the onset of symptoms. The most accurate test for the diagnosis is electro- myography (EMG). EMG is used to detect evidence of demyelination of the peripheral nerves.

Treatment. Treatment should be initiated as quickly as possible because available therapy becomes ineffective approximately 2 weeks after the onset of symptoms.

Intravenous immunoglobulin and plasmapheresis are equally effective treatments.   There    is no benefit to combination therapy. Glucocorticoids are not effective in the treatment of acute GBS. Also, it is extremely important to monitor the vital capacity in patients with GBS and initiate early respiratory support to prevent death from respiratory  failure.