What is Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), how is it treated, and what is its prognosis?

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): Diagnosis, Treatment, and Prognosis

Intravenous immunoglobulin (IVIg) is the first-line treatment for CIDP, with corticosteroids and plasma exchange as equally effective alternatives, based on the strongest evidence for reducing morbidity and improving quality of life.

What is CIDP?

CIDP is an acquired immune-mediated polyradiculoneuropathy characterized by:

• Progressive peripheral neuropathy with inflammatory demyelination of peripheral nerves
• Symptoms developing over at least 2 months (distinguishing it from acute forms like Guillain-Barré Syndrome)
• Motor weakness (proximal and distal) as the predominant feature
• Sensory symptoms including numbness, tingling, and neuropathic pain
• Reduced or absent deep tendon reflexes
• Possible cranial nerve involvement in some cases

CIDP is often misdiagnosed due to its heterogeneous presentation and overlap with other neuropathies. It represents about 5% of cases initially diagnosed as Guillain-Barré Syndrome that show repeated clinical relapses or deterioration ≥8 weeks after disease onset 1.

Diagnosis

Diagnosis relies on a combination of:

• Clinical features: Progressive symmetric or asymmetric motor and sensory deficits developing over ≥2 months
• Electrophysiological studies: Evidence of demyelination (conduction blocks, slowed conduction velocities)
• CSF analysis: Elevated protein with normal cell count (albuminocytologic dissociation)
• Nerve biopsy: May show demyelination and inflammatory infiltrates (not always required)
• MRI: May show nerve root enhancement or thickening

Treatment Algorithm

First-Line Therapies (all have similar efficacy):

1. Intravenous Immunoglobulin (IVIg):

   • Dosing: 2 g/kg divided over 2-5 days for induction
   • Maintenance: 1 g/kg every 3 weeks, adjusted based on response
   • Advantages: Rapid onset of action, well-tolerated
   • Disadvantages: Expensive, requires IV access, risk of thromboembolic events

2. Corticosteroids:

   • Dosing: Prednisone 1-1.5 mg/kg/day or pulse methylprednisolone
   • Advantages: Inexpensive, oral administration
   • Disadvantages: Significant side effects with long-term use

3. Plasma Exchange:

   • Protocol: Typically 5 exchanges over 2 weeks
   • Advantages: Rapid onset of action
   • Disadvantages: Requires specialized equipment, venous access, and more invasive

Second-Line Therapies (for refractory cases):

• Immunosuppressants:

  • Methotrexate (5-10 mg/week)
  • Azathioprine
  • Mycophenolate mofetil
  • Cyclosporine

• Rituximab: Particularly effective in certain subtypes

Newer Treatment Options:

• Subcutaneous Immunoglobulin (SCIg): Provides a new option that increases independence and improves tolerability 2, 3

Treatment Monitoring

• Regular assessment of muscle strength and sensory function
• Electrophysiological studies to monitor improvement in nerve conduction
• Functional assessments to evaluate impact on activities of daily living
• Monitoring for treatment-related side effects
• Consideration of dose reduction or treatment discontinuation in stable patients

Prognosis

The prognosis of CIDP is generally favorable with appropriate treatment:

• About 80% of patients respond to first-line therapies 4
• Early treatment is crucial to prevent permanent nerve damage and disability
• Long-term outcomes vary:
  • Complete remission: 10-30% of patients
  • Partial improvement with ongoing treatment requirement: 40-60%
  • Refractory disease: 10-15%

Important Considerations and Pitfalls

• Misdiagnosis: CIDP is frequently misdiagnosed. Ensure diagnostic criteria are met before initiating immunotherapy.
• Treatment Delays: Early treatment is essential to prevent permanent nerve damage.
• Treatment Duration: Optimal duration is unclear; consider trial of dose reduction/discontinuation after prolonged stability.
• Monitoring Response: Regular clinical assessments are crucial to determine treatment efficacy.
• Comorbidities: Consider patient's comorbidities when selecting treatment (e.g., diabetes with corticosteroids, renal impairment with IVIg).
• Refractory Cases: Consider referral to specialized neuromuscular centers for difficult-to-treat cases.

CIDP represents a treatable cause of chronic neuropathy, and with appropriate therapy, most patients can achieve significant improvement in function and quality of life.