Chronic Inflammatory Demyelinating Polyradiculopathy

Diseases, , ,

Synonyms:

Chronic inflammatory demyelinating polyradiculoneuropathy a.k.a. Chronic inflammatory demyelinating polyneuropathy, CIDP

Diagnosis:

Is by clinical findings supported by +NCS/EMG and occasionally nerve biopsy

Clinical features:

Clinical: >2 months, gradual onset, usually sensorimotor, arms & legs, proximal weakness & distal weakness, usually spares the cranial nerves, thickened nerves may occur.

NCS/EMG Nerve conduction studies:

Key features: Evidence of demyelination, rarely secondary axonal degeneration
CMAP:

  • Conduction block, Temporal dispersion
  • Decreased conduction velocities & prolonged distal latencies.
  • Amplitude: normal apart from conduction block

SNAP:

  • Decreased conduction velocities & prolonged distal latencies.
  • Amplitudes: normal or decreased
  • Prolonged F latencies.

EMG: normal or mild denervation changes, decreased recruitment (neuropathic recruitment)

Pathology, nerve biopsy:

  • Endoneurium: Inflammation: Infiltrate of macrophages & lymphocytes, Perivascular
  • Luxol fast blue: Onion bulb formation: demyelination & remyelination
  • Demyelinated or thinly myelinated fibres, they are variable within a fascicle
  • Axonal degeneration if longstanding
  • Immunohistochemsitry: macrophages, CLA for lymphocytes

Teased fibres:

  • Demyelination
  • Features more prominent in nerve roots (autopsy specimen),

 

CSF analysis, Albuminocytological dissociation:

Protein75-200 mg/dL
Raised IgG
Normal WCC

CIDP Variants:

  • CIDP, idiopathic
  • CIDP with paraproteinemia, includes:
    • MGUS, Waldenstrom’s macroglobulinemia, multiple myeloma, plasmacytoma, POEMS syndrome, B cell lymphoma, CLL,
  • CIDP with SLE, inflammatory bowel disease, sarcoidosis, chronic active hepatitis,
  • CIDP with HIV
  • CIDP with hepatitis B, hepatitis C
  • CIDP with Diabetes mellitus, thyrotoxicosis
  • CIDP with hereditary demyelinating neuropathies
  • CIDP with bone marrow & organ transplantation

Investigations to consider:

Blood tests:

  • FBC, blood chemistry panel, Creatinine, Mg, Phosphate
  • Fasting blood glucose & HbA1c
  • HIV testing
  • TFTs, LFTs: chronic active hepatitis
  • SPEP with IFE: paraproteinemia
  • If MGUS noted on SPEP: immunofixation, UPEP, uric acid, beta 2 – microglobulin, lactate dehydrogenase, rheumatoid factor, serum cryoglobulins,
  • If signs of POEMS syndrome (peripheral lymphadenopathy, hepatosplenomegaly, macroglossia) then serum VEGF levels.
  • ANA, ESR, CRP, complement
  • LP, CSF analysis, including cytology
  • Hepatitis serology
  • ACE level, Ca++: sarcodosis
  • Anti-MAG, anti-GM1
  • Heavy metal screen
  • Porphyria testing

Nerve biopsy in atypical cases
Abdominal ultrasound: in POEMS syndrome
Skeletal survey or low dose CT whole body: if paraproteinemia is present

Treatment:

  • Intravenous immunoglobulin IVIg 2g/kg divided over 5 days & repeat monthly & then space out treatment
  • or plasma exchange and repeat:
    • One plasma volume (40-50 mL/kg) X5 exchanges (i.e. total 200-250 mL/kg) over 7-14 days.
  • or Prednisolone high dose 60-80mg (or 1.5mg/Kg in children) for 2-4 weeks and switch to alternate day therapy, then taper to maintenance dose after maximum response is achieved. Prophylaxis & treatment of steroid complications

If unresponsive to treatment, consider:

  • Azathioprine p.o. 1mg/kg X2 weeks then increase to 2-3mg/kg.monitor FBC & LFTs
  • or cyclophosphamide 50mg/kg I.V. for 4 days, then G-CSF on day 10
  • or interferon Beta 30 microg/kg I.M.
  • or Rituximab 375 mg/m-2 I.V. every 4 weeks
  • or etanercept 25 mg SubQ twice a week

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