🧠Resistant CIDP

🧠 Resistant CIDP (Chronic Inflammatory Demyelinating Polyneuropathy)

Definition:
Resistance occurs when CIDP fails to respond to standard therapy, relapses rapidly, or progresses despite treatment.

🔹 Definition Criteria

• ❌ Failure to respond to ≥2 first-line treatments (IVIG, corticosteroids, plasma exchange)
• 🔄 Dependence on continuous therapy; relapse on dose reduction/withdrawal
• ⚡ Progressive disease despite appropriate treatment

🔹 Causes of Treatment Resistance

• 🧩 Misdiagnosis: hereditary neuropathy, POEMS, paraproteinemic neuropathy, vasculitic neuropathy
• ⚕️ Coexisting conditions: diabetes, renal disease, systemic autoimmune disorders
• 🔬 Atypical CIDP variants: MADSAM (Lewis–Sumner), DADS, nodopathy (antibody-mediated)
• 🧪 Antibody-mediated nodopathies: NF155, CNTN1, Caspr1 → often IVIG-resistant, may respond to rituximab

🔹 Standard First-Line Treatments

• 💉 IVIG: 2 g/kg over 2–5 days, then 1 g/kg every 3–4 weeks
• 🌡 Corticosteroids: oral prednisone 1 mg/kg/day or pulsed IV methylprednisolone
• ⚗️ Plasma exchange (PLEX): 3–5 sessions over 1–2 weeks

🔹 Second-Line / Rescue Therapies

Used in resistant/refractory cases

1️⃣ Immunosuppressive / Immunomodulatory Agents

• 🧴 Azathioprine: 2–3 mg/kg/day
• 💊 Mycophenolate mofetil: 1–2 g/day
• ⚗️ Cyclosporine: 3–5 mg/kg/day
• 💉 Cyclophosphamide: monthly IV 0.5–1 g/m²
• 🌡 Methotrexate: 7.5–25 mg weekly

2️⃣ Monoclonal Antibodies

• 🧬 Rituximab: IVIG-resistant or paranodal antibody-positive CIDP
• 🧪 Eculizumab: experimental, complement-mediated forms
• 💊 Infliximab / Tocilizumab: rare/off-label

3️⃣ Autologous Hematopoietic Stem Cell Transplant (AHSCT)

• For severe refractory cases
• Can induce long-term remission

🔹 Emerging & Targeted Therapies

• 💉 Subcutaneous immunoglobulin (SCIg): maintenance for IVIG-dependent patients
• 🧬 FcRn antagonists: efgartigimod, rozanolixizumab (clinical trials)
• ⚡ Bortezomib: potential in refractory antibody-mediated forms

🔹 Management Strategy

1. 🧠 Reconfirm diagnosis (NCS/EMG, CSF, exclude mimics)
2. 🧪 Screen for nodal/paranodal antibodies (NF155, CNTN1, Caspr1)
3. 🔄 Switch or combine therapies
   • IVIG → Steroids or PLEX
   • Low-dose steroid + IVIG
4. ⚡ If confirmed refractory → escalate to immunosuppressants or rituximab
5. 📊 Monitor disability scales (INCAT, MRC sum score, grip strength)

🔹 Practical Example

• Patient unresponsive to IVIG & corticosteroids →
• 🧬 Test anti-NF155 antibodies
  • ✅ Positive → start rituximab 375 mg/m² weekly × 4
  • ❌ Negative → consider cyclophosphamide or mycophenolate mofeti