What is the workup for Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)?

Diagnostic Workup for Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

The comprehensive diagnostic workup for CIDP must include neurological consultation, electrodiagnostic studies, lumbar puncture, and MRI imaging to establish the diagnosis and rule out mimicking conditions. 1

Initial Diagnostic Evaluation

Clinical Assessment

• Evaluate for symmetrical, motor-predominant peripheral neuropathy with both distal and proximal weakness
• Assess for large-fiber abnormalities (weakness and ataxia) which typically predominate
• Note that small-fiber abnormalities (autonomic dysfunction and pain) are less common 2
• Document temporal pattern: chronic, progressive, monophasic, or relapsing-remitting course

Essential Diagnostic Tests

1. Neurological Consultation

   • Required for proper evaluation and management 1
   • Expert assessment of clinical features and interpretation of diagnostic studies

2. Electrodiagnostic Studies

   • Nerve conduction studies (NCS) and electromyography (EMG) to detect:
     • Slowed conduction velocities
     • Temporal dispersion
     • Conduction block
     • Evidence of demyelination 2
   • These studies are crucial for differentiating CIDP from axonal neuropathies

3. MRI of Spine with and without Contrast

   • Evaluate for nerve root enhancement/thickening
   • Rule out compressive lesions
   • Identify inflammatory changes 1, 3

4. Lumbar Puncture for CSF Analysis

   • Cell count (typically normal)
   • Protein levels (typically elevated - "albuminocytologic dissociation")
   • Glucose levels
   • Cytology (to rule out malignancy) 3, 1

5. Laboratory Screening

   • Complete blood count
   • Comprehensive metabolic panel
   • Inflammatory markers (ESR, CRP)
   • Screening for reversible causes:
     • Vitamin B12 and folate levels
     • Thyroid function tests (TSH)
     • HIV testing
     • Serum protein electrophoresis with immunofixation (to detect monoclonal gammopathies)
     • HbA1c and blood glucose (to rule out diabetes) 1, 2

Additional Testing to Rule Out Mimics

1. Autoimmune/Inflammatory Workup

   • Antinuclear antibody (ANA)
   • Rheumatoid factor
   • Anti-neutrophil cytoplasmic antibodies (ANCA)
   • Serum antiganglioside antibodies 1

2. Metastatic Bone Surveys

   • To rule out osteosclerotic myeloma 2

3. Consideration of Nerve Biopsy

   • Not routinely required but may be helpful in atypical cases
   • Can show segmental demyelination, onion-bulb formation, and endoneurial inflammatory infiltrates 2

Diagnostic Criteria

The diagnosis of CIDP is based on the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria, which combine:

• Clinical features
• Electrodiagnostic evidence of demyelination
• Supportive criteria (elevated CSF protein, MRI findings, nerve biopsy findings, treatment response) 4

Pitfalls and Caveats

1. Misdiagnosis is Common

   • CIDP can be confused with other chronic polyneuropathies 4
   • Careful application of diagnostic criteria is essential

2. Atypical Presentations

   • Be aware of CIDP variants (multifocal CIDP, distal CIDP, etc.) that may not fulfill typical diagnostic criteria 2

3. Monitoring Disease Progression

   • No reliable biomarker exists for disease activity
   • Serial clinical assessments are key to evaluating treatment response 5

4. Importance of Early Diagnosis

   • Early treatment can prevent irreversible neurological deficits
   • CIDP is treatable with immunomodulatory therapies 6

By following this systematic diagnostic approach, clinicians can accurately diagnose CIDP and distinguish it from other chronic polyneuropathies, enabling prompt initiation of appropriate treatment to prevent disability.