Diagnosis
Guillain-Barré is a syndrome diagnosed by a collection of symptoms (see Table 22,21,31), including subacute developing paralysis, symmetrical bilateral weakness beginning at onset, and diminishing to absent reflexes.21,31 Other causes for rapidly developing weaknesses should be ruled out (see Table 310,21,26,31). Lumbar puncture typically shows increased protein levels with a normal white cell count; however, neither this test nor electrophysiologic evaluation offers significant value for diagnosis of GBS.21,26,31
During the acute phase of GBS (within three weeks of onset), there is found an elevation of CSF protein (> 550 mg/L) without an elevation in white blood cells. This phenomenon, called albuminocytologic dissociation, reflects inflammation of the nerve roots and is considered the hallmark of GBS.2
MRI can also facilitate the diagnosis of GBS; it demonstrates anterior and posterior intrathecal spinal nerve roots and cauda equina.32 In patients with GBS, evidence supporting breakdown of the blood–nerve barrier can be seen in abnormal gadolinium enhancement of the intrathecal nerve roots on MRI.33
When electrophysiologic studies are performed, they typically reveal slowing nerve conduction, prolonged distal latencies, and partial motor conduction block.34 The characteristic finding of early demyelination is conduction block, a reduction in the amplitude of the muscle action potential after stimulation of the distal, as opposed to the proximal, nerve.28 Nerve conduction studies may help in the diagnosis and classification of GBS—and, to a limited extent, formulation of a prognosis. Such alternative diagnoses as myositis and myasthenia gravis may be excluded by neurophysiology.26 Early in GBS, neurophysiologic abnormalities may be very mild or occasionally normal; test results may not correlate with clinical disability.35,36
The clinician cannot depend on clinical features alone to predict respiratory decline.31 Frequent evaluations of respiratory effort, by measurement of maximal inspiratory pressures and vital capacity, should be performed at the bedside to monitor diaphragmatic strength. Respiratory ventilation should be initiated if the patient becomes hypoxic or experiences a rapid decline in vital capacity (ie, below 60% of predicted value).10 Mechanical ventilation is more likely to be required in patients with a negative inspiratory force of less than 30 cm H2O.31
Treatment
Guillain-Barré syndrome has an acute onset and progression. Patients quickly become nonambulatory and may require total ventilation due to paralysis. Therapeutic options are IVIG or plasmapheresis (plasma exchange).37-40 Corticosteroids do not appear to benefit patients with GBS.41,42
Several mechanisms appear to contribute to the effectiveness of immunoglobulin.38,39 Infused IVIG interferes with antigen presentation, inhibits antibody production, neutralizes pathologic autoantibodies, and modulates other immunologic events involved in the pathogenesis of autoimmune neuromuscular diseases, including GBS.43 Adverse reactions, which are usually minor, include headache, fever, chills, myalgia, and malaise. In rare instances, anaphylaxis or renal failure may occur.15,44
In plasmapheresis, blood is removed from the body and dialyzed, with circulating antibodies and immunoglobulins removed from the plasma; fresh frozen plasma, albumin, or saline is administered. This treatment, performed via central venous catheter, should be initiated as soon as possible after onset of symptoms but can be implemented as late as 30 days after GBS onset. Plasmapheresis requires personnel trained in dialysis, which may not be performed in all hospitals. Possible adverse events include infection and hemorrhage. Laboratory values must be monitored for hypokalemia and hypocalcemia.45,46
Supportive Care
Patients with GBS require intensive care and very close monitoring for complications of respiratory difficulty and autonomic dysfunction. Individualized programs should be initiated for patients in the acute phase of GBS, aimed at the prevention of contractures and skin breakdown.10 Exercise programs, as conducted with the case patient, should also help relieve the fatigue syndromes that accompany GBS.
Immobilization associated with bed rest incurs a risk for pulmonary emboli and DVT; this has been found true during the first 12 weeks after symptom onset in patients with GBS who remain immobile.47 The use of antiembolic hose and sequential compression devices can help reduce the risk for thrombotic events.10 Use of enoxaparin or heparin is recommended for nonambulating patients until they are able to walk, with Gaber et al47 specifying the use of low-molecular-weight heparin to reduce, but not eliminate, the risk for DVT.
The pain associated with GBS can be severe. Narcotic analgesics may be administered with careful monitoring of autonomic denervation. Long-term management of neuropathic pain may require adjuvant therapy, such as tricyclic antidepressants, gabapentin, or tramadol hydrochloride.10 According to Pandey et al,48 gabapentin alone may suffice for pain control in GBS, with minimal adverse effects. In certain rehabilitation facilities, tricyclic antidepressants, capsaicin, and transcutaneous nerve stimulation have been reported effective; during the early stages of treatment, until these treatments reach their full effect, pain medications such as tramadol or narcotics can provide temporary relief.29