Last reviewed: 19 Dec 2021
Last updated: 27 Oct 2021



History and exam

Key diagnostic factors

  • presence of risk factors
  • muscle weakness
  • paraesthesia
  • back/leg pain
  • respiratory distress
  • speech problems
  • areflexia/hyporeflexia
  • facial weakness
  • bulbar dysfunction causing oropharyngeal weakness
  • extra-ocular muscle weakness
  • facial droop
  • diplopia
  • dysarthria
  • dysphagia
  • dysautonomia
  • pupillary dysfunction
  • ophthalmoplegia

Other diagnostic factors

  • ptosis
  • altered level of consciousness
  • ataxia

Risk factors

  • preceding viral illness
  • preceding bacterial infection
  • preceding mosquito-borne viral infection
  • hepatitis E infection
  • immunisation
  • cancer and lymphoma
  • older age
  • HIV infection
  • COVID-19 infection
  • male

Diagnostic investigations

1st investigations to order

  • nerve conduction studies
  • lumbar puncture
  • LFTs
  • spirometry

Investigations to consider

  • anti-ganglioside antibody
  • serology
  • stool culture
  • HIV antibodies
  • spinal MRI
  • Borrelia burgdorferi serology
  • cerebrospinal fluid (CSF) meningococcal polymerase chain reaction
  • CSF cytology
  • CSF angiotensin-converting enzyme
  • chest x-ray
  • CSF West Nile polymerase chain reaction

Emerging tests

  • ultrasound imaging of peripheral nerves

Treatment algorithm



Saiju Jacob, MD, DPhil, MRCP (UK), FRCP (Lon)

Consultant Neurologist

Queen Elizabeth Neurosciences Centre

University Hospital Birmingham




SJ has served as an international advisory board member for Alexion, Alnylam, ArgenX, Regeneron, Immunovant, and UCB pharmaceuticals. He is currently an expert panel member of the Myasthenia Gravis consortium for ArgenX, and has received speaker fees from Terumo BCT and Eisai.


Dr Saiju Jacob would like to gratefully acknowledge Dr John B. Winer, Dr Michael T. Torbey, Dr Dhruvil J. Pandya, and Dr Prem A. Kandiah, previous contributors to this topic.


JBW, MTT, DJP, and PAK declare that they have no competing interests.

Peer reviewers

Cigdem Akman, MD

Division of Pediatric Neurology

Columbia University College of Physicians and Surgeons

New York



CA declares that he has no competing interests.

Robert Hadden, FRCP, PhD

Consultant Neurologist

King's College Hospital




RH has been paid by Baxter Healthcare Ltd for membership of its neurology advisory board, and is a co-author of several studies referenced in this topic.

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