Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is defined as a heterogeneous group of autoimmune polyradiculopathies, involving sensory, motor and autonomic nerves. It is the most common cause of rapidly progressive flaccid paralysis. It is believed to be one of a number of related conditions, sharing a similar underlying autoimmune abnormality, collectively known as anti-GQ1b IgG antibody syndrome.

Epidemiology

Most cases are preceded by upper respiratory tract infections or diarrhoea 1-3one to three weeks before itstheir onset, most commonly caused by Campylobacter jejuni (25-40% of patients are seropositive) ^1,3. Molecular mimicry with the bacterial agents is thought to cause the autoimmunity with the development of anti-GQ1b IgG antibodies. 

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

Clinical presentation

The classical presentation of Guillain-Barré syndrome includes symmetrical ascending muscle paresis or palsy/paralysis, areflexia or hyporeflexia along with a/hyporeflexia, and 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)
    • characterised by ataxia, areflexia without weakness and ophthalmoplegia
    • anti-GQ1b antibodies are present in most cases
  • polyneuritis cranialis ⁶

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

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

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

Chronic inflammatory demyelinating polyneuropathy (CIDP) is considered the chronic counterpart to Guillain-Barré syndrome.

Radiographic features

Radiological studies are orderedrequested 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, helping to exclude other aetiologies, such as transverse myelitis and compressive causes of polyradiculopathy.

MRI

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

Typical findings in Guillain-Barré syndrome are surface thickening and contrast enhancement on the conus medullaris and the nerve roots of the cauda equina 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 cranial nerve ¹.

Treatment and prognosis

Guillain-Barré syndrome is primarily managed with IV immunoglobulins or plasmapheresis along with supportive measures, which can speed up recovery ¹. 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 the 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-operativepostoperative, or post intrathecal injection)
• neurosarcoidosis
• leptomeningeal carcinomatosis and lymphoma
• chronic inflammatory demyelinating polyneuropathy (CIDP)
  • acute presentation of CIDP 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 ⁷
• rabies encephalitis (paralytic variant): similar presentation, but more fulminant course resulting in rapid demise in almost all cases