Not only does GBS appear in SAQs (Question 10 from the first paper of 2013)  but it inevitably finds its way into the hot cases. If there's a GBS at the hospital where the exam is being held, you bet your arse they're going in front of the candidates. Locally, chapters of interest include Approach to the ICU patient with generalised weakness and Features that distinguish Guillain-Barre syndrome from critical illness polyneuromyopathy.

Distally, a LITFL article on GBS offers an extensive and well-referenced revision resource.

Diagnostic criteria for GBS

 
  • Progressive course
  • Weakness in both arms and both legs
  • Areflexia

Features suggestive of GBS

  • Progression over days to 4 weeks
  • Symmetry of features
  • Cranial nerve involvement
  • Recovery after 2-4 weeks
  • Autonomic dysfunction
  • Absence of fever at onset
  • High protein in CSF

Features suggestive of poor prognosis in GBS

  • Age over 60
  • Rapid progression in less than 7 days
  • Mechanical ventilation
  • A preceding diarrhoeal illness

Overall, the mortality in GBS patients admitted to ICU is around 25% according to Oh's Manual

Sensitising infections

  • Campylobacter jejuni
  • CMV
  • Influenza A
  • Parainfluenza,
  • Varicella-zoster
  • Epstein–Barr virus
  • HIV
  • Mycoplasma

Characteristic features

Presentation

  • 2-8 weeks of minor illness
  • No fever to begin with
  • Ascending paraesthesia
  • Ascending neuropathy

Specific features

Laboratory findings

  • CSF protein is elevated, and monocytes and lymphocytes are present in the CSF
  • Blood IgG may be elevated
  • The Miller Fisher variant may have GQ1b antiganglioside antibodies and the axonal forms may have antiganglioside GM1 antibodies

Electrophysiology

  • Nerve conduction studies: reduced conduction velocity and prolonged distal latencies are the cardinal findings
  • LITFL lists the following NCS features:
    • Reduced conduction velocity
    • Multifocal conduction blocks
    • Abnormal temporal dispersion of compound muscle action potentials
    • Prolonged distal latencies
    • Prolonged F-waves

Radiological features

Important staging investigations

These are the investigations which will guide you as to whether you can afford to let the primary team monitor this patient for a while longer, or whether you need to take them to the ICU immediately and prepare for imminent intubation.

Spirometry - FVC

  • An FVC less than 20ml/kg (i.e. 1400ml for a normal 70kg male) is quoted by LITFL as a trigger for ICU admission, likely on the basis of a 2005 consensus statement.
  • Spanish guidelines recommend a decrease of 50% from FVC predicted by age/height/gender as a trigger for at least noninvasive ventilation (i.e. they are concerned about hypercapnea)
  • An FVC less than 15ml/kg is suggested as the trigger for invasive mechanical ventilation
  • Interestingly, these people may actually have a higher FVC while supine rather than sitting up, much like the patients with a high spinal injury.

MIPs - Maximum Inspiratory Pressures

  • If the MIP is less than 30cmH2O, they need a tube.
  • This demonstrates respiratory muscle weakness

MEPs - Maximum Expiratory Pressures

  • If the MEP is less than 40cmH2O, they need a tube.
  • As well as demonstrating respiratory and abdominal muscle weakness, this finding also suggests that the patient will be unable to generate enough pressure to cough effectively.

Peak Expiratory Flow

  • A PEF rate less than 250 L/min seems to be associated with a need for mechanical ventilation
  • Like the MEP, it is an indirect suggestion that the ability to cough has become impaired.
  • There is a distinct user friendliness advantage with the peak flow measurements. Whereas spirometry and MIP/MEP measurements are hard to organise, the peak flow meter is widely available, and any shaved ape could be trained to use it.

Supportive management

An excellent article exists to fill this section, and I will only touch on a few of the issues they have detailed recommendations for:

Why do we intubate these people?

  • They are too weak to support a satisfactory minute volume
  • They are too weak to cough
  • Their airway protection is lost when bulbar cranial nerves become involved

When do we offer them a tracheostomy?

  • Late, is the short answer.
  • If the pulmonary function tests fail to improve with treatment and two weeks of intubation has passed without change, a tracheostomy should be offered.
  • Patients showing subtle improvement might be able to wait for another week.

Specific management

  • Corticosteroids are counterproductive.
  • Plasmapheresis works: 4 exchanges of 1-2 plasma volumes, over 1-2 weeks.
    Plasma exchange for Guillain-Barre syndrome aims to clear the aetiological autoantibody from the bloodstream. In essence, we say "we have no idea which antibody is causing the demyelination, so we will get rid of all of them". The evidence seems to support a 5-treatment regimen; it seems that six treatments are no better than four. Because there is no missing proteins to replace, the exchanged plasma can be FFP or albumin - it does not seem to matter to the resolution of disease. However, because FFP has a slightly higher risk of transfusion reactions, so in general albumin is the recommended replacement solution, unless there are specific reasons to replace blood proteins.
  • IV immunoglobulin is at least as effective as plasmapheresis. Dose is 2g/kg. The college answer to Question 20 from the first paper of 2016 mentions a Cochrane review, probably referring to Hughes et al (2014) who demonstrated that in severe disease IVIG within the first 2 weeks "hastens recovery as much as plasma exchange".

References

Oh's Intensive Care manual:

Chapter   57   (pp. 617)  Neuromuscular  diseases  in  intensive  care by George  Skowronski  and  Manoj  K  Saxena

van den Berg, Bianca, et al. "Guillain-Barre syndrome: pathogenesis, diagnosis, treatment and prognosis." Nature Reviews Neurology 10.8 (2014): 469-482.

Yuki, Nobuhiro, and Hans-Peter Hartung. "Guillain–Barré syndrome." New England Journal of Medicine 366.24 (2012): 2294-2304.

Raphael, J. C., et al. "Plasma exchange for Guillain-Barré syndrome." Cochrane Database Syst Rev 2.2 (2002).

Venkata Umakant, K., B. Seshulakshmi, and B. Srinivasa Rao. "Miller Fisher Syndrome–An Atypical Clinical Presentation." Intern Med 3.119 (2013): 2.

Berlit, Peter, and Josef Rakicky. "The Miller Fisher syndrome: review of the literature." Journal of Neuro-Ophthalmology 12.1 (1992): 57-63.

Odaka, M., N. Yuki, and K. Hirata. "Anti-GQ1b IgG antibody syndrome: clinical and immunological range." Journal of Neurology, Neurosurgery & Psychiatry70.1 (2001): 50-55.

Alkan, Ozlem, et al. "Spinal MRI findings of guillain-barre syndrome." Journal of radiology case reports 3.3 (2009): 25.

Cabrera Serrano, M., and A. A. Rabinstein. "Usefulness of pulmonary function tests and blood gases in acute neuromuscular respiratory failure." European Journal of Neurology 19.3 (2012): 452-456.

Farrero, Eva, et al. "Guidelines for the Management of Respiratory Complications in Patients With Neuromuscular Disease." Archivos de Bronconeumología (English Edition) 49.7 (2013): 306-313.

Hughes, Richard AC, et al. "Supportive care for patients with Guillain-Barré syndrome." Archives of neurology 62.8 (2005): 1194-1198.

Massam, M., and R. S. Jones. "Ventilatory failure in the Guillain-Barré syndrome." Thorax 35.7 (1980): 557-558.

González-Suárez, Inés, et al. "Guillain-Barré Syndrome: Natural history and prognostic factors: a retrospective review of 106 cases." BMC neurology 13.1 (2013): 95.

Dhand, Upinder K. "Clinical approach to the weak patient in the intensive care unit." Respiratory care 51.9 (2006): 1024-1041.

Hughes, Richard AC, Anthony V. Swan, and Pieter A. van Doorn. "Intravenous immunoglobulin for Guillain‐Barré syndrome." The Cochrane Library (2014).