Saturday, May 6, 2017

Guillain-Barré Syndrome

Also known as infectious polyneuritis, Landry-Guillain-Barré syndrome, and acute idiopathic polyneuritis, Guillain-Barré syndrome is an acute, rapidly progressive, and potentially fatal form of polyneuritis that causes muscle weakness and mild distal sensory loss.
This syndrome can occur at any age but is most common between ages 30 and 50; it affects both sexes equally. Recovery is spontaneous and complete in about 95% of patients, although mild motor or reflex deficits in the feet and legs may persist. The prognosis is best when symptoms clear between 15 and 20 days after onset.

The precise cause of Guillain-Barré syndrome is unknown, but it may be a cell-mediated immune response with an attack on peripheral nerves in response to a virus. The major pathologic effect is segmental demyelination of the peripheral nerves.
Because this syndrome causes inflammation and degenerative changes in both the posterior (sensory) and the anterior (motor) nerve roots, signs of sensory and motor losses occur simultaneously.

Predisposing factors
About 50% of patients with Guillain-Barré syndrome have a recent history of minor febrile illness, usually an upper respiratory tract infection or, less commonly, gastroenteritis. When infection precedes the onset of Guillain-Barré syndrome, signs of infection subside before neurologic features appear.
Other possible precipitating factors include surgery, rabies or swine influenza vaccination, viral illness, Hodgkin’s or some other malignant disease, and systemic lupus erythematosus.

Signs and symptoms
Muscle weakness, the major neurologic sign, usually appears in the legs first (ascending type) and then extends to the arms and facial nerves within 24 to 72 hours. Sometimes, muscle weakness develops in the arms first (descending type) or in the arms and legs simultaneously. In milder forms of the disease, muscle weakness may affect only the cranial nerves or may not occur.
Paresthesia, another common neurologic sign, sometimes precedes muscle weakness but vanishes quickly. Some patients with the disorder never develop this symptom.
Other clinical features include facial diplegia (possibly with ophthalmoplegia [ocular paralysis]), dysphagia or dysarthria and, less commonly, weakness of the muscles supplied by cranial nerve XI (spinal accessory nerve).
Muscle weakness develops so quickly that muscle atrophy doesn’t occur, but hypotonia and areflexia do. Stiffness and pain in the form of a severe “charley horse” occur in many cases.

Three-phase course
The clinical course of Guillain-Barré syndrome is divided into three phases:
  1. The initial phase begins when the first definitive symptom develops; it ends 1 to 3 weeks later, when no further deterioration is noted.
  2. The plateau phase lasts from several days to 2 weeks.
  3. The recovery phase is believed to coincide with remyelination and axonal process regrowth. This phase extends over 4 to 6 months; patients with severe disease may take up to 2 years to recover, and recovery may not be complete.
Significant complications of Guillain-Barré syndrome include mechanical ventilatory failure, aspiration pneumonia, sepsis, joint contractures, and deep vein thrombosis. Unexplained autonomic nervous system involvement may cause sinus tachycardia or bradycardia, hypertension, postural hypotension, and loss of bladder and bowel sphincter control.

A history of preceding febrile illness (usually a respiratory tract infection) and typical clinical features suggest Guillain-Barré syndrome.
Several days after onset of signs and symptoms, the cerebrospinal fluid (CSF) protein level begins to rise, peaking in 4 to 6 weeks, probably as a result of widespread inflammatory disease of the nerve roots. The CSF white blood cell count remains normal, but in severe disease, CSF pressure may rise above normal.
Probably because of predisposing infection, the complete blood count shows leukocytosis with the presence of immature forms early in the illness, but blood study results soon return to normal. Electromyography may show repeated firing of the same motor unit, instead of widespread sectional stimulation.
Nerve conduction velocities are slowed soon after paralysis develops. The diagnosis must rule out similar diseases such as acute poliomyelitis.

  • Primarily supportive, treatment consists of endotracheal intubation or tracheotomy if the patient has difficulty clearing secretions.
  • A trial dose of prednisone may be given if the course of the disease is relentlessly progressive
  • If prednisone produces no noticeable improvement after 7 days, the drug is discontinued. 
  • Plasmapheresis is useful during the initial phase but offers no benefit if begun 2 weeks after onset. 
  • High doses of immunoglobulins may be administered I.V. to decrease the autoimmune response but must be started as soon as possible to have an effect.

Special considerations
  • Watch for ascending sensory loss, which precedes motor loss. Also, monitor vital signs and level of consciousness.
  • Assess and treat respiratory dysfunction. If respiratory muscles are weak, take serial vital capacity recordings. Use a respirometer with a mouthpiece or a face mask for bedside testing. Some patients require ventilatory assistance.
  • Obtain arterial blood gas measurements. Because neuromuscular disease results in primary hypoventilation with hypoxemia and hypercapnia, watch for a partial pressure of oxygen (PaO2) below 70 mm Hg, which signals respiratory failure. Be alert for signs of a rising partial pressure of carbon dioxide (confusion, tachypnea).
  • Auscultate for breath sounds, turn and reposition the patient regularly, and encourage coughing and deep breathing.
  • Begin respiratory support at the first sign of dyspnea (in adults, a vital capacity less than 800 ml; in children, less than 12 ml/kg of body weight) or a decreasing PaO2.
  • If respiratory failure becomes imminent, establish an emergency airway with an endotracheal tube.
  • Give meticulous skin care to prevent skin breakdown and contractures.
  • Establish a strict turning schedule; inspect the skin (especially the sacrum, heels, and ankles) for breakdown, and reposition the patient every 2 hours.
  • After each position change, stimulate circulation by carefully massaging pressure points. Also, use foam, gel, or alternating-pressure pads at points of contact.
  • Perform passive range-of-motion exercises within the patient’s pain limits, perhaps using a Hubbard tank. Remember that the proximal muscle groups of the thighs, shoulders, and trunk will be the most tender and cause the most pain on passive movement and turning.
  • When the patient’s condition stabilizes, change to gentle stretching and active assistance exercises.
  • Assess the patient for signs of dysphagia (coughing, choking, “wet-sounding” voice, increased presence of rhonchi after feeding, drooling, delayed swallowing, regurgitation of food, and weakness in cranial nerves V, VII, IX, X, XI, or XII).
  • Take measures to minimize aspiration: elevate the head of the bed, position the patient upright and leaning forward when eating, feed semisolid food, and check the mouth for food pockets.
  • Encourage the patient to eat slowly and remain upright for 15 to 20 minutes after eating.
  • A speech pathologist and modified video fluoroscopy can assist in identifying the best feeding strategies.
  • If aspiration can’t be minimized by diet and position modification, nasogastric feeding is recommended.
  • As the patient regains strength and can tolerate a vertical position, be alert for postural hypotension. Monitor blood pressure and pulse rate during tilting periods and, if necessary, apply toe-to-groin elastic bandages or an abdominal binder to prevent postural hypotension.
  • Inspect the patient’s legs regularly for signs of thrombophlebitis (localized pain, tenderness, erythema, edema, positive Homans’ sign), a common complication of Guillain-Barré syndrome.
  • To prevent thrombophlebitis, apply antiembolism stockings and give prophylactic anticoagulants as needed.
  • If the patient has facial paralysis, give eye and mouth care every 4 hours.
  • Protect the corneas with isotonic eyedrops and conical eye shields.
  • Encourage adequate fluid intake (2 qt [2 L]/day), unless contraindicated.
  • Watch for urine retention. Measure and record intake and output every 8 hours, and offer the bedpan every 3 to 4 hours.
  • If urine retention develops, begin intermittent catheterization as needed. Because the abdominal muscles are weak, the patient may need manual pressure on the bladder (Credé’s method) before he can urinate.
  • To prevent and relieve constipation, offer prune juice and a high-bulk diet. If necessary, give daily or alternate-day suppositories (glycerin or bisacodyl) or Fleet enemas.
  • Before discharge, prepare a home care plan. Teach the patient how to transfer from bed to wheelchair and from wheelchair to toilet or tub and how to walk short distances with a walker or cane.
  • Teach the family how to help the patient eat, compensating for facial weakness, and how to help him avoid skin breakdown. Stress the need for a regular bowel and bladder routine.
  • Refer the patient for physical therapy, occupational therapy, and speech therapy, as needed.

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