Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP)

Umair Hamid (1), Saud Khan (2)
1 - University of Health and Sciences, Pakistan
2 - Department of Neurology, Tritus Regional Medical Center


Introduction

  • Classified under the eponym Guillain-Barre syndrome (GBS)
  • Other variants of GBS include Acute Motor Axonal Neuropathy (AMAN), Acute Motor and Sensory Axonal Neuropathy (ASMAN), and the Miller Fisher syndrome (MFS).
  • AIDP is acute monophasic immune-mediated polyradiculoneuropathy provoked by a preceding infection

Epidemiology

  • Mean age of onset of 40 years affecting slightly more males than females of all ages, races and nationalities
  • Worldwide incidence of GBS ranges from 0.6 to 4.0/100,000 people

Etiology

  • AIDP is most common form of GBS in North America, Europe and most of the developed world representing about 85% to 90% of cases
  • ⅔ patients give history of antecedent respiratory tract or GI tract infection
  • Campylobacter jejuni infection is most commonly observed in 25-50% of the adult patients, with higher frequency in Asian countries.
  • Campylobacter associated GBS has worse prognosis, manifests slow recovery and with greater residual neurologic disability.
  • Other precipitants include EBV, CMV, mycoplasma, pneumonia, and influenza-like illnesses
  • Also has an association with HIV infection; predominantly in those who are not profoundly immunocompromised

Pathogenesis

  • Molecular Mimicry: auto-antibodies cross-react with peripheral nerve components because of sharing of cross-reactive epitopes
  • Immune response can be directed towards myelin or axon of peripheral nerve
  • Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP): When directed against epitopes in myelin or schwann cell membrane; cellular + humoral immune responses are involved
  • Progression of disease for about two to four weeks
  • In a study pop. of 494 adult patients, disease nadir was reached in 2 week in 80% and within 4 weeks in 97%
  • If disease progression is more than 8 weeks, it is classified as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
  • Subacute inflammatory demyelinating polyneuropathy (SIDP) is considered if nadir is reached between 4 and 8 weeks

Table 1: Clinical Features of AIDP

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Rare features

  • Unusual clinical features of AIDP include: papilledema, facial myokymia, hearing loss, meningeal signs, vocal cord paralysis, and mental status changes.
  • Posterior reversible encephalopathy syndrome, also called reversible posterior leukoencephalopathy syndrome has been associated with GBS in children and adults likely related to acute hypertension from dysautonomia

Investigations

  • CSF Analysis:
    • Cytoalbuminologic dissociation: normal cell count and increased protein level
    • In few cases (about 15%), mild increase in CSF cell count was seen
  • Electrodiagnostic findings:
    • Absent H reflexes
    • Decreased motor nerve conduction velocity
    • Sural sparing pattern (early stages)
    • Prolonged distal motor latency
    • Increased F wave latency
    • Conduction blocks
    • Temporal dispersion
    • Serial NCS over weeks are sometimes needed to reliably distinguish between AMAN and ADIP
  • MRI:
    • Thickening and enhancement of the intrathecal spinal nerve roots and cauda equina
    • Involvement of anterior spinal roots may be present, or both anterior and posterior roots

Diagnostic Criteria

In 1990, Asbury and Cornblath expanded the diagnostic criteria devised of 1978 which is applicable even today.
Features required:
  • Progressive motor weakness of more than one limb.
  • Areflexia
Features strongly supportive of the diagnosis:
  • Progression of symptoms and signs
  • Relative symmetry
  • Mild sensory symptoms or signs
  • Cranial nerve involvement
  • Recovery
  • Autonomic dysfunction
  • Pain
  • No fever at the onset
  • Elevated protein in CSF with cell count ≤50cells/mm3
  • Electrodiagnostic abnormalities consistent with GBS

Features that make diagnosis of GBS doubtful:

  • Sensory level
  • Marked, persistent asymmetry of weakness
  • Bowel and bladder dysfunction at onset
  • Severe and persistent bowel and bladder dysfunction
  • Severe pulmonary dysfunction with little or no limb weakness at onset
  • Fever at onset
  • CSF pleocytosis

Table 2: Differential Diagnosis of AIDP

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Management

  • Triage and Initial Management algorithm:
    • Urgent intubation if clinical signs of respiratory distress, oxygen desaturation, or hypercapnia are present
    • Admit to ICU and consider elective intubation if
      • Moderate to severe or rapidly progressive appendicular weakness with bulbar dysfunction
      • Symptoms of respiratory insufficiency
      • Abnormal spirometry(FVC<20mL/Kg, MIP>-30 mmH2O, MEP<40 mmH2O, or >30% decrease from baseline values), evidence of aspiration
      • Pronounced dysautonomia
    • Monitor on the ward if none of the above four mentioned points
  • Dysautonomia:
    • Manifestations:
      • Tachycardia
      • Urinary retention
      • Hypertension alternating with hypotension
      • Orthostatic hypotension
      • Bradycardia
      • Arrhythmias
      • Ileus
      • Loss of sweating
      • So the management must include:
    • Management:
      • Monitoring:
        • Cardiac rhythm
        • Close blood pressure monitoring
        • Fluid status
        • Intra-arterial monitoring if significant blood pressure fluctuations are present
        • Daily abdominal auscultation to monitor for bowel silence and for adynamic ileus
      • Treatment:
        • Low-dose phenylepinephrine if fluids are not effective for hypotension (Only low doses of carefully titrated short-acting vasoactive agents should be used to avoid possible effects of denervation hypersensitivity)
        • Labetalol, esmolol, or nitroprusside for MAP>125 mmHg
        • Intervention with administration of atropine and cardiac pacing might be required in life-threatening arrhythmias like AV block and asystole
        • Erythromycin or neostigmine may be effective for ileus
        • Gabapentin or carbamazepine for ICU pain control in acute phase
        • TCAs, gabapentin, carbamazepine, or pregabalin can be used for long-term pain management
  • Main modalities of treating GBS:
    • Plasmapheresis and IVIg are the mainstay of treatment for AIDP or for other variants of GBS
    • Oral steroids and methylprednisolone have not shown any benefits in this disorder
    • Combination of IVIg and plasma exchange is not significantly better than either alone
    • Plasma exchange:
      • Four to six rounds of plasmapheresis over 8-10 days.
      • Evidence based conclusion:
        • Median time to recover with plasma exchange was shorter than control group
        • Time of onset of motor recovery in mild GBS was significantly shorter than control group
        • More effective when started within 7 days of onset
        • 4 rounds of treatment were superior to 2 in moderate severe GBS
      • Adverse effects:
        • Hypotension
        • Sepsis
        • Problems related to central venous catheter:
          • Local hematoma
          • Pneumothorax
          • Line-related infection
        • Mild coagulopathy
        • Hypocalcemia
        • Transfusion reaction (including transfusion related acute lung injury)
      • Intravenous immune globulin (IVIg):
        • 0.4 gram/kg per day for 5 days
        • Evidence based results:
          • Studies compared IVIg with plasmapheresis
          • IVIg is as effective as plasma exchange for GBS
          • Patients assigned to IVIg are significantly less likely to discontinue treatment than those on plasmapheresis
        • Adverse effects:
          • Aseptic meningitis
          • Chest pain
          • Infusion reaction:
            • Headache
            • Shivering
            • Myalgia
          • Anaphylaxis (if IgA deficient)
          • Acute renal failure
          • Hyperviscosity leading to stroke (rare)
    • No evidence shows a second course of IVIg to be effective in patients of GBS that continue to deteriorate

Table 3: Complications of AIDP

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Prognosis

  • Respiratory Failure:
    • 15-30% of AIDP patients need ventilatory support
    • Predictors of respiratory failure:
      • Evidence based conclusion: mechanical ventilation was required in >85% patients with four out of the following six predictors
        • Time of onset to admission <7 days
        • Inability to cough
        • Inability to stand
        • Inability to lift the elbows
        • Inability to lift the head
        • Increase in LFTs
  • Disability:
    • 20% of patients are unable to walk after 6 months
    • Most patients have residual pain and fatigue due to persistent axonal loss
  • Mortality rate
    • 3-10%
    • Death can occur in acute progressive state most probably due to ventilatory insufficiency or pulmonary complications, or from dysautonomia like arrhythmia
    • Death can also occur in later stage
  • Treatment Related Fluctuations (TRF)
    • 10% patients will deteriorate within the first 8 weeks after the start of IVIg which is called TRF
    • Repeated treatment with IVIg has been shown to be beneficial in these patients
  • CIDP with acute onset (A-CIDP)
    • 5% of patients initially diagnosed with AIDP were eventually found to have acute onset CIDP
    • Diagnosis should be considered in patients :
      • Initially diagnosed with AIDP who have 3 or more periods with clinical deterioration
      • Or when there is new deterioration after 8 weeks from onset of weakness
  • TRF vs A-CIDP:
    • The difference is significant management wise.
    • There might be improvement with retreatment in TRF whereas patients with A-CIDP need chronic maintenance treatment with IVIg or a switch to corticosteroid treatment
  • GBS Disability Score:
    • It uses level of disability be documented using a scale from 0 to 6.
  • EGOS:
    • The Erasmus GBS Outcome Score (EGOS) is a prognostic model based on age, diarrhea, and GBS disability at 2 weeks after hospital admission
    • It accurately predicts the chance of being able to walk independently at 6 months
  • mEGOS:
    • Modified EGOS was developed to apply at hospital admission and at day 7 of hospital stay as compared to original EGOS model which applied on 14th day of stay
    • It requries Medical Research Council (MRC) Scale for Muscle Strength score instead of disability
    • According to this study, poor outcome is associated with:
      • Older age
      • Rapid disease progression
      • Severe disease indicated by GBS disability score or MRC sumscore
      • C. jejuni or CMV positive serology
      • Preceding respiratory tract infection
  • NCS might also have prognostic value; patients with features of demyelination are more prone to need mechanical ventilation
  • Low compound action potentials (CMAPs) are the most consistent findings predictive of poor outcome

Further reading

Comprehensive review article: Willison, H. J., Jacobs, B.C.. van Doorn, P. A. (2016). Guillain-Barré syndrome. The Lancet. 388:10045(717-727). https://doi.org/10.1016/S0140-6736(16)00339-1

Bibliography

  • Walgaard, C. et. al (2011). Early recognition of poor prognosis in Guillain-Barre syndrome. Neurology. 76(11): 968-975. doi: 10.1212/WNL.0b013e3182104407
  • Fokke, C. et. al (2014). Diagnosis of Guillain-Barre syndrome and validation of Brighton criteria. Brain. 10.1093/brain/awt285. Epub 2013 Oct 26.
  • Rees, J. H. et. al (1995). Campylobacter jejuni infection and Guillain–Barré syndrome. New England Journal of Medicine, 333(21), 1374-1379.
  • Visser, L. H. et. al (1995). Guillain-Barré syndrome without sensory loss (acute motor neuropathy) A subgroup with specific clinical, electrodiagnostic and laboratory features. Brain, 118(4), 841-847.
  • Jacobs B.C. et. al (1998). The spectrum of antecedent infections in Guillain-Barre syndrome: A case-control study. Neurology. 51(4):1110-1115.
Dimachkie, M. M., & Barohn, R. J. (2013). Guillain-Barré syndrome and variants. Neurologic clinics, 31(2), 491-510.
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