Guillain-Barré Syndrome

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Guillain-Barré Syndrome

Anatomic Alterations of the Lungs Associated with Guillain-Barré Syndrome

Guillain-Barré syndrome is a relatively rare autoimmune disorder of the peripheral nervous system in which flaccid paralysis of the skeletal muscles and loss of reflexes develop in a previously healthy patient. In severe cases, paralysis of the diaphragm and ventilatory failure can develop. Clinically, this is a medical emergency. If the ventilatory failure is not properly managed, mucous accumulation with airway obstruction, alveolar consolidation, and atelectasis may develop.

Paralysis of the skeletal muscles develops in response to various pathologic changes in the peripheral nerves. Microscopically, the nerves show demyelination, inflammation, and edema. As the anatomic alterations of the peripheral nerves intensify, the ability of the neurons to transmit impulses to the muscles decreases, and eventually paralysis ensues (see Figure 28-1). Box 28-1 lists other names in the literature for Guillain-Barré syndrome.

The major pathologic or structural changes of the lungs associated with the ventilatory failure that may accompany Guillain-Barré syndrome are as follows:

Etiology and Epidemiology

The annual incidence of Guillain-Barré syndrome is 1 to 2 per 100,000 people in the United States. The mortality rate is 4% to 6%, and the morbidity rate (permanent disabling weakness, imbalance, or sensory loss) is 5% to 10%. Although the condition is uncommon in early childhood, it may occur in all age groups and in either gender. A greater incidence has been noted among people 45 years of age and older, among male subjects, and among Caucasians (the condition is 50% to 60% more common in Caucasians). There is no obvious seasonal clustering of cases.

The precise cause of Guillain-Barré syndrome is not known. It is probably an immune disorder that causes inflammation and deterioration of the patient’s peripheral nervous system. Elevated levels of immunoglobulin M (IgM) antibodies against myelin glycolipid have been found in the serum of patients with Guillain-Barré syndrome. Antibodies that are cell-mediated are thought to be responsible for peripheral nerve demyelination and inflammation. Lymphocytes and macrophages appear to attack and strip off the myelin sheath of the peripheral nerves and leave swelling and fragmentation of the neural axon (see Figure 28-1). It is believed that the myelin sheath covering the peripheral nerves (or the myelin-producing Schwann cell) is the actual target of the immune attack.

The onset of Guillain-Barré syndrome often occurs 1 to 4 weeks after a febrile episode caused by a mild respiratory or gastrointestinal viral or bacterial infection. In about 60% of the cases, Campylobacter jejuni is identified as the cause of the preceding infection. Other precipitating factors include infectious mononucleosis, parainfluenza 2, vaccinia, variola, measles, mumps, hepatitis A and B viruses, Mycoplasma pneumoniae, Salmonella Typhi, and Chlamydia psittaci. Although the significance of the association is controversial, during the nationwide immunization campaign in the United States in 1976, more than 40 million adults were vaccinated with swine influenza vaccine, and more than 500 cases of Guillain-Barré syndrome were reported among the vaccinated individuals, with 25 deaths.

Clinical Presentation

The general clinical history of patients with Guillain-Barré syndrome is (1) symmetric muscle weakness in the distal extremities accompanied by paresthesia or dysesthesias (tingling, burning, shocklike sensations), (2) pain (throbbing, aching, especially in the lower back, buttocks, and leg), and (3) numbness. The muscle paralysis then spreads upward (ascending paralysis) to the arms, trunk, and face. The muscle weakness and paralysis may develop within a single day or over several days. The muscle paralysis generally peaks in about 2 weeks. Deep tendon reflexes are commonly absent. The patient often drools and has difficulty chewing, swallowing, and speaking. The management of oral secretions may be a problem. Respiratory muscle paralysis, followed by acute ventilatory failure, occurs in 10% to 30% of cases.

Although Guillain-Barré syndrome is typically an ascending paralysis—that is, moving from the lower portions of the legs and body upward—muscle paralysis may affect the facial and arm muscles first and then move downward. Although the weakness is commonly symmetric, a single arm or leg may be involved before paralysis spreads. The paralysis also may affect all four limbs simultaneously. Progression of the paralysis may stop at any point. After the paralysis reaches its maximum, it usually remains unchanged for a few days or weeks. Improvement generally begins spontaneously and continues for weeks or, in rare cases, months. About 10% of patients have permanent residual neurological deficits. About 90% of patients make a full recovery, but the recovery time may be as long as 3 years.

If diagnosed early, patients with Guillain-Barré syndrome have an excellent prognosis. The diagnosis typically is based on the patient’s clinical history (e.g., sudden ascending paralysis), cerebrospinal fluid (CSF) findings, and abnormal electromyography (EMG) results. The CSF in patients with Guillain-Barré syndrome shows an elevated protein level (500 mg/dL), without an increased lymphocyte count, called albuminocytologic dissociation. EMG helps to establish the diagnosis and the extent of neurologic involvement. The EMG measures the electrical activity of a muscle in response to nerve stimulation. It also measures the nature and speed of electrical conduction along a nerve.

image OVERVIEW of the Cardiopulmonary Clinical Manifestations Associated with Guillain-Barré Syndrome

The following clinical manifestations result from the pathologic mechanisms caused (or activated) by Atelectasis (see Figure 9-8), Alveolar Consolidation (see Figure 9-9), and Excessive Bronchial Secretions (see Figure 9-12)—the major anatomic alterations of the lungs associated with Guillain-Barré syndrome (when ventilatory failure is not properly managed) (see Figure 29-1).

CLINICAL DATA OBTAINED AT THE PATIENT’S BEDSIDE

The Physical Examination

Autonomic Nervous System Dysfunctions

Autonomic nervous system dysfunction develops in approximately 50% of all cases. The autonomic dysfunction involves the overreaction or underreaction of the sympathetic or parasympathetic nervous system. Clinically, the patient may manifest various cardiac arrhythmias, such as sinus tachycardia (the most common), bradycardia, ventricular tachycardia, atrial flutter, atrial fibrillation, and asystole.

Hypertension and hypotension also may be seen. Although the loss of bowel and bladder sphincter control is uncommon, transient sphincter paralysis may occur during the evolution of symptoms. The autonomic nervous system involvement may be transient or may persist throughout the duration of the disorder.

CLINICAL DATA OBTAINED FROM LABORATORY TESTS AND SPECIAL PROCEDURES

Pulmonary Function Test Findings* (Restrictive Lung Pathology)

FORCED EXPIRATORY FLOW RATE FINDINGS

FVC FEVT FEV1/FVC ratio FEF25%-75%
N or ↓ N or ↑ N or ↓
FEF50% FEF200-1200 PEFR MVV
N or ↓ N or ↓ N or ↓ N or ↓

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