Guillain-Barré syndrome

Guillain–Barré syndrome (GBS) is defined as heterogeneous group of autoimmune polyradiculopathy, involving sensory, motor and autonomic nerves and is the most common cause of rapidly progressive flaccid paralysis ². 

Epidemiology

Most cases preceded by upper respiratory tract infections or diarrhoea 1-3 weeks before its onset, most commonly caused by Campylobacter jejuni (25-40% seropositive) ^1,3. Molecular mimicry with the bacterial agents is thought to cause the autoimmunity. 

Other predisposing factors include recent surgery, lymphoma and systemic lupus erythematosus (SLE) ². 

Clinical presentation

Classical presentation of GBS includes symmetrical ascending muscle paresis or palsy, areflexia or hyporeflexia along with variable degree of sensory or autonomic involvement.

Several subtypes have been described including:

• acute inflammatory demyelinating polyradiculoneuropathy (AIDP)
• axonal subtypes:
  • acute motor axonal neuropathy(AMAN) / Chinese paralytic syndrome
  • acute motor sensory axonal neuropathy (AMSAN)
    • both axonal subtypes are thought to be due to antibodies to gangliosides which result in macrophages invading the axons at the nodes of Ranvier ³
• regional GBS syndromes:
  • Miller Fisher variant (MFS/ MFV)
    • characterized by ataxia, areflexia without weakness and ophthalamoplegia
    • anti GQ1b antibodies are present in most cases

Guillain–Barré syndrome is diagnosed by combination of clinical presentation, CSF study and electrophysiological criteria. 

CSF abnormalities are characterized by increase protein without pleocytosis, which is a non-specific finding, seen in many of the conditions which mimic GBS on imaging and clinically ^1-2. 

Nerve conduction abnormalities include slow or blocked nerve conduction, prolongation of distal latency and f-waves. 

Chronic inflammatory demyelinating polyneuropathy (CIPD) is considered the chronic counterpart to GBS. 

Pathology

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Radiographic features

Radiologic studies are ordered to exclude other causes and in cases where nerve conduction studies and CSF examination are equivocal. MRI of the spine is most useful helps excluding other aetiologies such as transverse myelitis and compressive causes of polyradiculopathy. 

MRI

It is essential that contrast be administered if the diagnosis is suspected as non-contrast sequences are essentially normal ². 

Typical findings in Guillain–Barré syndrome are nerve root thickening and enhancement surrounding the conus and extending along the cauda equina, resulting from breakdown in the blood brain barrier, which usually prevents enhancement ².

The most common site of enhancement in Guillain–Barré syndrome is considered to be anterior nerve roots, although enhancement of the posterior nerve roots is also seen ². 

In the brain the facial nerve (CN VII) is the most commonly affected ¹.

Treatment and prognosis

Guillain–Barré syndrome is primarily managed with IV immunoglobulins or plasmapharesisplasmapheresis along with supportive measures, which can speed up recovery ¹.

Typically Typically improvement occurs after a number of weeks to months ¹ although there is significant mortality (3-10%) ⁵.

History and etymology

The syndrome was named after Georges Guillain (1876-1961) and Jean Alexandre Barré (1880-1967), French neurologists. André Strohl (1887-1977), a French physiologist, worked together with the both neurologists and is third author in the description done in 1916, and for this reason the syndrome is also referred as Guillain-Barré-Strohl syndrome.

Differential diagnosis

The differential is essentially that of nerve root / cauda equina enhancement: 

• AIDS-related polyradiculopathy
• arachnoiditis from any cause (e.g. post operative, or post intrathecal injection) 
• neurosarcoidosis
• leptomeningeal carcinomatosis and lymphoma
• chronic inflammatory demyelinating polyneuropathy (CIPD)
  • actue presentation of CIPD can be similar to GBS
  • difficult to differentiate in the first 6 weeks
  • after 6-8 weeks GBS should be improving whereas CIDP will demonstrate chronic inflammation ⁴
• Lyme disease
• rabies encephalitis (paralytic variant): similar presentation, but more fulminant course resulting in rapid demise in almost all cases