Guillain-Barré syndrome is an acute polyneuropathy characterized by immune-mediated peripheral nerve myelin sheath or axon destruction. The prevailing theory is that antibodies directed against myelin sheath and axons of peripheral nerves are formed in response to a preceding viral or bacterial illness. Symptoms are at their worst in 2 to 4 weeks, and recovery can vary from weeks to a year.
The classic Guillain-Barré syndrome is a demyelinating disorder of the peripheral nerves. It is sometimes preceded by a viral or bacterial illness. Common infectious precipitants include Campylobacter jejuni, Zika virus, Cytomegalovirus, Epstein-Barr virus, or Mycoplasma pneumoniae. The cause is unknown but thought to be associated with antiganglioside antibodies. Signs and symptoms of the classic form include an ascending symmetric weakness or paralysis and areflexia or hyporeflexia. Paralysis may ascend to the diaphragm, compromising respiratory function and requiring mechanical ventilation. Autonomic dysfunction may be present as well. There are many variants of Guillain-Barré syndrome. The demyelinating form (lymphocytic infiltration of the myelin sheath of peripheral nerves) is common in the US and the axonal form (motor paralysis with sensory function intact) in Asia. The Miller-Fisher syndrome variant is characterized by ophthalmoplegia, ataxia, and areflexia. Severity of symptoms and duration of illness depend upon the form of the disease.
The diagnosis is mostly historical, but lumbar puncture and electrodiagnostic information can improve confidence in the diagnosis. Table 172–2 lists the specific diagnostic criteria.
Diagnostic Criteria for Classic Guillain-Barré Syndrome
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Diagnostic Criteria for Classic Guillain-Barré Syndrome
Progression over days to weeks
Recovery beginning 2–4 weeks after cessation of progression
Relative symmetry of symptoms
Mild sensory signs and symptoms
Cranial nerve involvement (Bell's palsy, dysphagia, dysarthria, ophthalmoplegia)
Autonomic dysfunction (tachycardia, bradycardia, dysrhythmias, wide variations in blood pressure, postural hypotension, urinary retention, constipation, facial flushing, anhydrosis, hypersalivation)
Absence of fever at onset
Cytoalbuminologic dissociation of cerebrospinal fluid (high protein and low white cell count)
Typical findings on electromyogram and nerve conduction studies
CSF analysis shows high protein levels (>45 milligrams/dL) and WBC counts typically <10 cells/mm3, with predominantly mononuclear cells. When there are >100 cells/mm3, other considerations include HIV, Lyme disease, syphilis, sarcoidosis, tuberculous or bacterial meningitis, leukemic infiltration, or CNS vasculitis. Electrodiagnostic testing demonstrates demyelination. Nerve biopsy reveals a mononuclear inflammatory infiltrate. If MRI is performed to rule out alternative diagnoses, it will show enhancement of affected nerves.
The first step in management is assessment of respiratory function. Airway protection in advance of respiratory compromise decreases the incidence of aspiration and other complications. A well-established monitoring parameter is vital capacity, with normal values ranging from 60 to 70 mL/kg. A simple bedside assessment of respiratory status is obtained by trending values reached when the patient counts from 1 to 25 with a single breath. Avoid depolarizing neuromuscular blockers like succinylcholine for intubation in Guillain-Barré syndrome due to the risk of a hyperkalemic response.
Both IV immunoglobulin and plasmapheresis shorten the time to recovery. Neither has been shown to be superior to the other, nor are they more efficacious when used together. There are adverse effects seen with both modalities of treatment. IV immunoglobulin has been associated with thromboembolism and aseptic meningitis; plasmapheresis is associated with hemodynamic instability, but a lower rate of relapse. In general, IV immunoglobulin is more widely available and less cumbersome to administer. Corticosteroids are of no benefit and may be harmful.1
Admit patients with acute Guillain-Barré syndrome to a unit where cardiac, respiratory, and neurologic functions can be monitored. Even if a patient does not initially meet the criteria for intubation, intensive care unit admission may still be indicated in order to avoid sudden, unmonitored respiratory failure (Table 172–3).2
Managing Respiratory Failure in Guillain-Barré Syndrome
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Managing Respiratory Failure in Guillain-Barré Syndrome
Indications for intubation
Vital capacity <15 mL/kg
Declining one breath count
Pao2<70 mm Hg on room air
Bulbar dysfunction (difficulty with breathing, swallowing, or speech)
Indications for admission to intensive care unit
Patients with 4 or more of the following findings: inability to stand, inability to lift the head, inability to lift the elbows, insufficient cough, time from symptom onset to hospital admission <7 days or elevated liver enzymes
Initial vital capacity <20 mL /kg
Initial negative inspiratory force less than –30 cm of water
Decrease of >30% of vital capacity or negative inspiratory force
Inability to ambulate
Treatment with plasmapheresis
BELL'S PALSY AND UNILATERAL FACIAL PARALYSIS
Bell's palsy or idiopathic facial nerve palsy is the most common cause of unilateral facial paralysis. There are 23 to 25 cases per 100,000 annually, affecting men and women equally. Cranial nerve VII, the facial nerve, supplies motor innervation to the muscles of expression of the face and scalp, the stapedius muscle, and taste to the anterior two thirds of the tongue. The cause of Bell's palsy is not clear. Herpes simplex virus DNA and antigens have been discovered around the facial nerve of affected patients. However, antiviral medications are ineffective, casting doubt on the once predominant theory that herpes simplex virus is responsible for the disease.
Idiopathic Bell's palsy may be preceded by pain around or behind the ear. Onset of facial paralysis is acute, with maximal symptoms in 2 to 3 days. Facial numbness or hyperesthesia can accompany paralysis. Subtle dysfunction of cranial nerves V, VIII, IX, and X may be associated; for example, patients may also complain of decreased taste or hyperacusis due to paralysis of the stapedius muscle. On exam, patients will have facial droop, effacement of wrinkles and forehead burrows, and inability to completely close the eye. Recurrent idiopathic Bell's palsy occurs in a small number of patients.
Diagnosis of idiopathic Bell's palsy is based on the history and physical exam and is a diagnosis of exclusion of other conditions that can cause facial palsy. The most important alternative diagnoses to exclude are ear infections and stroke. Always perform an ear examination to identify otitis media and malignant otitis, and palpate the mastoids for tenderness, because infections of the ear and mastoids can affect the mastoid, tympanic, labyrinthine, or meatal segments of the cranial nerve VII (Figure 172–1).
Relationships of cranial nerve VII to the inner and middle ear. [Adapted with permission from Lalwani AK (ed): Current Diagnosis & Treatment in Otolaryngology-Head & Neck Surgery, 3rd ed. McGraw-Hill, Inc., 2012. Sect XVI Facial Nerve Chapter 70. Figure 70–3, Part A.]
When a central process causes facial paralysis, the forehead will be spared, as the forehead is supplied by cranial nerve VII arising near the pontomedullary junction, with crossed innervation. Peripheral facial nerve palsies will manifest as weakness throughout the facial nerve distribution, including the forehead. Middle cerebral artery ischemia or stroke consists of hemiparesis, facial plegia sparing the forehead, and sensory loss all contralateral to the affected cortex. Rarely, a brainstem stroke may mimic Bell's palsy if the stroke affects the area where the facial nerve wraps around the abducens (cranial nerve VI) nucleus. Brainstem stroke findings include peripheral facial nerve palsy and ipsilateral gaze palsy due to ischemia of the abducens nucleus. So, test extraocular muscle function for all patients suspected of having Bell's palsy. Any patient with facial paralysis sparing the forehead or inability to abduct an eye should undergo neuroimaging to assess for stroke. No imaging or laboratory testing is needed in patients with high suspicion of Bell's palsy unless further studies are required to exclude alternative diagnoses.
A number of viral infections and other disorders have been associated with Bell's palsy (e.g., mumps, Epstein-Barr virus, rubella, Lyme disease; see later discussion) but are suspected by associated signs and symptoms.
Treatment and Disposition
Treatment with corticosteroids increases the frequency of complete recovery.3 The dose of prednisone is 1 milligram/kg per day PO for 7 days. There is no benefit from antiviral medications, either alone or in addition to steroid therapy.4 There is insufficient evidence to support acute surgical decompression. The greatest risk to patients with facial paralysis is corneal abrasions and keratitis due to eyelid weakness and incomplete eye closure. Patch the affected eye if there is incomplete closure, and provide instructions for ophthalmology follow-up to determine when the patch can be removed. Make sure there is no lid movement under the eye patch. Provide patients with ocular lubricants, including a tear replacement for daytime and a more viscous topical lubricant for sleep.
Most patients begin to recover within 3 weeks, but about 15% will have permanent paralysis. Ensure follow-up within 7 days with a primary care physician or ear, nose, and throat specialist.
RAMSEY HUNT SYNDROME (HERPES ZOSTER OTICUS)
Ramsey Hunt syndrome is a herpes zoster infection of the geniculate ganglion. Signs and symptoms include unilateral facial nerve palsy, severe pain, and a vesicular eruption on the face. Ramsey Hunt syndrome may be indistinguishable from Bell's palsy if paralysis precedes the vesicular eruption. Cranial nerve VIII may also be involved with associated vertigo, nausea, and hearing loss. As opposed to classic Bell's palsy, when active herpes zoster is suspected, treatment is with both steroids (prednisone 1 milligram/kg per day PO for 7 days) and antivirals (famciclovir 500 mg PO three times a day for 7 days or valacyclovir 1 gram PO three times a day for 7 days).5
ACUTE NEUROPATHIES OF LYME DISEASE
Lyme disease may cause a broad range of nervous system disease, both peripheral and central, acute and chronic. Consider Lyme disease as the causative agent in patients who have facial palsy with erythema migrans, tick bite, or arthritis. Some patients will have bilateral facial palsy. Multifocal Lyme polyradiculopathy may occur in the acute phase of Lyme infection. Signs and symptoms include burning and painful neuropathy, plexopathy, and other mononeuropathies.
Diagnosis is based on history of tick bite and a physical examination that uncovers an attached tick or erythema chronicum migrans rash (see Figure 251–18). If CSF is obtained, it will show the mononuclear pleocytosis typical of Lyme infection. Treatment is with doxycycline 100 milligrams twice daily for 14 to 21 days. Facial nerve palsies in Lyme disease represent the secondary stage of illness and require 1 month of treatment with doxycycline (100 milligrams PO twice a day) or amoxicillin, cefuroxime, ceftriaxone, or azithromycin.