Guillain-Barré syndrome

Guillain-Barré syndrome
ICD-10	G61.0
ICD-9	357.0
DiseasesDB	5465
MeSH	D020275

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, MBBS [2]

Pathophysiology

All forms of Guillain-Barré syndrome are due to an immune response to foreign antigens (such as infectious agents or vaccines) but mistargeted to host nerve tissues instead (a form of antigenic mimicry). The targets of such immune attack are thought to be gangliosides, which are complex glycosphingolipids present in large quantities on human nerve tissues, especially in the nodes of Ranvier. An example is the GM1 ganglioside, which can be affected in as many as 20-50% of cases, especially in those preceded by Campylobacter jejuni infections. Another example is the GQ1b ganglioside, which is the target in the Miller Fisher syndrome variant (see below).

The end result of such autoimmune attack on the peripheral nerves is inflammation of myelin and conduction block, leading to a muscle paralysis that may be accompanied by sensory or autonomic disturbances.

However, in mild cases, axonal function remains intact and recovery can be rapid if remyelination occurs. In severe cases, such as in the AMAN or AMSAN variants (see below), axonal degeneration occurs, and recovery depends on axonal regeneration. Recovery becomes much slower, and there is a greater degree of residual damage. Recent studies on the disease have demonstrated that approximately 80% of the patients have myelin loss, whereas, in the remaining 20%, the pathologic hallmark of the disease is indeed axon loss.

Physical Examination

The disease is characterized by weakness which affects the lower limbs first, and rapidly progresses in an ascending fashion. Patients generally notice weakness in their legs, manifesting as "rubbery legs" or legs that tend to buckle, with or without dysthesias (numbness or tingling). As the weakness progresses upward, usually over periods of hours to days, the arms and facial muscles also become affected. Frequently, the lower cranial nerves may be affected, leading to bulbar weakness, (oropharyngeal dysphagia, that is difficulty with swallowing, drooling, and/or maintaining an open airway) and respiratory difficulties. Most patients require hospitalization and about 30% require ventilatory assistance. Facial weakness is also commonly a feature, but eye movement abnormalities are not commonly seen in ascending GBS, but are a prominent feature in the Miller-Fisher variant (see below.)

Sensory loss, if present, usually takes the form of loss of proprioception (position sense) and areflexia (complete loss of deep tendon reflexes), an important feature of GBS. Loss of pain and temperature sensation is usually mild. In fact, pain is a common symptom in GBS, presenting as deep aching pain usually in the weakened muscles, which patients compare to the pain from overexercising. These pains are self-limited and should be treated with standard analgesics. Bladder dysfunction may occur in severe cases but should be transient. If severe, spinal cord disease should be suspected.

Fever should not be present, and if it is, another cause should be suspected.

In severe cases of GBS, loss of autonomic function is common, manifesting as wide fluctuations in blood pressure, orthostatic hypotension, and cardiac arrhythmias.

Classification

Although ascending paralysis is the most common form of spread in GBS, other variants also exist.

• Miller-Fisher Syndrome (MFS) is a rare variant of GBS and manifests as a descending paralysis, proceeding in the reverse order of the more common form of GBS. It usually affects the ocular muscles first and presents as ophthalmoplegia, ataxia, and areflexia. Anti-GQ1b antibodies are present in 90% of cases.
• Acute motor axonal neuropathy (AMAN), aka. Chinese Paralytic Syndrome, attacks motor nodes of Ranvier and is prevalent in China and Mexico. The disease may be seasonal and recovery can be rapid. Anti-GD1a antibodies are present. Anti-GD3 antibodies are found more frequently in AMAN
• Acute motor sensory axonal neuropathy (AMSAN) is similar to AMAN but also affects sensory nerves with severe axonal damage. Recovery is slow and often incomplete.

Diagnosis

The diagnosis of GBS usually depends on findings such as rapid development of muscle paralysis, areflexia, absence of fever, and a likely inciting event. CSF and ECD is used almost every time to verify symptoms, but because of the acute nature of the disease, they may not become abnormal until after the first week of onset of signs and symptoms.

• CSF - typical CSF findings include an elevated protein level (100 - 1000 mg/dL) without an accompanying pleocytosis (increased cell count). A sustained pleocytosis may indicate an alternative diagnosis such as infection.

The diagnosis is confirmed by the presence of Albuminocytological dissociation in the CSF

• Electrodiagnostics - electromyography (EMG) and nerve conduction study (NCS) may show prolonged distal latencies, conduction slowing, conduction block, and temporal dispersion of compound action potential in demyelinating cases. In primary axonal damage, the findings include reduced amplitude of the action potentials without conduction slowing.

Diagnostic criteria

• Required
  • Progressive, relatively symmetrical weakness of 2 or more limbs due to neuropathy
  • Areflexia
  • Disease course < 4 weeks
  • Exclusion of other causes (see below)
• Supportive
  • relatively symmetric weakness accompanied by numbness and/or tingling
  • mild sensory involvement
  • facial nerve or other cranial nerve involvement
  • absence of fever
  • typical CSF findings obtained from lumbar puncture
  • electrophysiologic evidence of demyelination from electromyogram

Differentiating Guillain-Barré syndrome from other Diseases

• acute myelopathies with chronic back pain and sphincter dysfunction
• botulism with early loss of pupillary reactivity
• diphtheria with early oropharyngeal dysfunction
• Lyme disease polyradiculitis and other tick-borne paralyses
• porphyria with abdominal pain, seizures, psychosis
• vasculitis neuropathy
• poliomyelitis with fever and meningeal signs
• CMV polyradiculitis in immunocompromised patients
• critical illness neuropathy
• myasthenia gravis
• poisonings with organophosphate, poison hemlock, thallium, or arsenic
• paresis caused by West Nile Virus

Treatment

Supportive care with monitoring of all vital functions is the cornerstone of successful management in the acute patient. Of greatest concern is respiratory failure due to paralysis of the diaphragm. Early intubation should be considered in any patient with a vital capacity (VC) <20 ml/kg, a Negative Inspiratory Force (NIF) <-25 cmH₂O, more than 30% decrease in either VC or NIF within 24 hours, rapid progression of disease, or autonomic instability.

Once the patient is stabilized, treatment of the underlying condition should be initiated as soon as possible. Either high-dose intravenous immunoglobulins (IVIg) at 400mg/kg for 5 days or plasmapheresis can be administered, as they are equally effective and a combination of the two is not significantly better than either alone. Therapy is no longer effective after 2 weeks after the first motor symptoms appear, so treatment should be instituted as soon as possible. IVIg is usually used first because of its ease of administration and safety profile, with a total of five daily infusions for a total dose of 2 g/kg body weight (.4kg each day). The use of intravenous immunoglobulins is not without risk, occasionally causing hepatitis, or in rare cases, renal failure if used for longer than five days. Glucocorticoids have NOT been found to be effective in GBS. If plasmapheresis is chosen, a dose of 40-50 mL/kg plasma exchange (PE) is administered four times over a week.

Following the acute phase, the patient may also need rehabilitation to regain lost functions. This treatment will focus on improving ADL (activities of daily living) functions such as brushing teeth, washing and getting dressed. Depending on the local structuring on health care, there will be established a team of different therapists and nurses according to patient needs. An occupational therapist can offer equipment (such as wheel chair and cutlery) to help the patient achieve ADL independence. A physiotherapist would plan a progressive training programme, and guide the patient to correct, functional movement, avoiding harmful compensations which might have a negative effect in the long run. There would also be a doctor, nurse and perhaps a speech trainer involved, depending on the needs of the patient. This team contribute with their knowledge to guide the patient towards his or her goals, and it is important that all goals set by the separate team members are relevant for the patient's own priorities. After rehabilitation the patient should be able to function in his or her own home and attend necessary training as needed.

A fundamental part of hospital treatment should fall on the family. As hospitals reduce healthcare it becomes impossible to care for patients around the clock. Patients that reach total paralysis are unable to signal or call for help and this is where family care becomes so important. Family members provide care and support that patients desperately need and medical staff sometimes don't understand or are unable to provide. Due to inactivity the body loses tone and flexibility. It's suggested that learning Range of Motion from medical staff and using stretches and keeping the joints pliable will aid the patient to recover sooner than letting them lay in a vegetative position. This also helps with circulation and the onset of bedsores. Bedsore prevention mattresses provide comfort to the patient if the family is unable to maintain 24 hour care. This is important because hospital recovery from Guillain-Barre can last from weeks to months.