What are the diagnostic criteria and treatment options for a patient suspected of having Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)?

CIDP Diagnostic Criteria and Treatment

Diagnostic Criteria

The diagnosis of CIDP requires progressive or relapsing bilateral weakness with areflexia developing over more than 2 months, confirmed by nerve conduction studies showing demyelination and CSF analysis demonstrating cytoalbuminologic dissociation (elevated protein with normal cell count). 1, 2, 3

Clinical Features Required for Diagnosis

• Progressive bilateral weakness affecting both arms and legs, with both distal and proximal involvement, progressing beyond 2 months (this distinguishes CIDP from Guillain-Barré syndrome which progresses over days to 4 weeks) 1, 3, 4
• Absent or decreased tendon reflexes in affected limbs at some point during the clinical course 1, 3
• Large-fiber abnormalities predominate (weakness and ataxia), while small-fiber abnormalities (autonomic dysfunction and pain) are less common 4

Essential Diagnostic Testing

• Nerve conduction studies must demonstrate demyelinating features including slowed conduction velocities, temporal dispersion, and conduction block 1, 3, 4
• CSF analysis typically shows cytoalbuminologic dissociation (elevated protein with normal cell count), though this is not specific for CIDP 1, 2, 4
• Serum protein electrophoresis with immunofixation to exclude monoclonal gammopathies 1, 4
• Metastatic bone survey to exclude osteosclerotic myeloma 1, 4
• HIV testing should be performed 1, 4

Additional Diagnostic Considerations

• MRI of brachial or lumbosacral plexus can identify focal or diffuse peripheral nerve abnormalities 2
• Nerve biopsy may be useful in atypical presentations that don't meet standard electrophysiological criteria, demonstrating segmental demyelination, onion-bulb formation, and endoneurial inflammatory infiltrates 1, 3, 5, 4

Common diagnostic pitfall: Some patients with CIDP may not fulfill strict electrophysiological criteria but still respond to immunomodulatory treatment—in these cases, nerve biopsy can confirm the diagnosis. 6, 5

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Treatment Algorithm

First-Line Treatment for Severe or Rapidly Progressive Disease

For severe or rapidly progressive CIDP, initiate pulse methylprednisolone 1g IV daily for 3-5 days PLUS IVIG 2g/kg administered over 5 days (0.4 g/kg/day). 1, 2

• Hospital admission is warranted for severe symptoms with functional impairment 1
• Plasma exchange is an established first-line option, particularly effective in severe cases 1

Critical timing caveat: Do not perform plasmapheresis immediately after IVIG administration, as it will remove the therapeutic immunoglobulin. 1

First-Line Treatment for Mild to Moderate Disease

For mild to moderate CIDP, initiate oral prednisone 1 mg/kg daily with gradual taper over at least 4-6 weeks. 1

• Oral corticosteroids alone or with immunosuppressive therapy achieve 60-75% response rates 1

Treatment Response Monitoring

• Do not assume treatment failure if progression continues in the first 4 weeks—40% of patients do not improve initially but may still benefit from therapy 1
• Treatment response should be judged by objective measures including improvement in neurological examination and functional disability outcomes 7, 4
• Do not delay treatment beyond 2 weeks, as this is associated with severe neurological deficit and poor outcomes 1

Second-Line Treatment for Refractory Cases

For patients with limited or no improvement after first-line therapy, rituximab should be considered in consultation. 1, 2

• Other immunosuppressants include methotrexate, azathioprine, or mycophenolate mofetil for maintenance therapy or when symptoms do not resolve after 4 weeks 1

Treatment-Related Fluctuations (TRFs)

• Approximately 6-10% of patients experience TRFs, defined as disease progression within 2 months following initial treatment-induced improvement 1
• Repeat the full course of IVIG or plasma exchange for TRFs, as this indicates the treatment effect has worn off while inflammation persists 1

Long-Term Management

• For patients in remission receiving non-glucocorticoid immunosuppressive therapy, consider discontinuation after 18 months rather than indefinite treatment 1
• Axon loss associated with demyelination is the most important factor of disability and resistance to treatment 6

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CIDP Variants to Recognize

• Multifocal Acquired Demyelinating Sensory and Motor Neuropathy (MADSAM/Lewis-Sumner Syndrome) presents with asymmetric involvement and preserved reflexes in unaffected areas 2
• Predominantly motor or sensory variants may have normal CSF and fail to show clear electrophysiological demyelination, yet still respond to immunomodulatory treatment 6