Interventional Pain Procedures

IPP Basics & Assessment - Ground Zero Prep

• Goal: Diagnose & treat pain via minimally invasive techniques.
• Indications: Chronic pain refractory to conservative Rx (neuropathic, MSK, cancer).
• Contraindications (Absolute): Infection at site, uncorrected coagulopathy (INR > 1.5, Plt < 50k), true allergy, patient refusal.
• Patient Assessment:
  • History: 📌 OLD CARTS (Onset, Location, Duration, Character, Aggravating/Relieving, Radiation, Timing, Severity).
  • Exam: Focused neuro/MSK. Pain scales (VAS, NRS).
  • Labs/Imaging: Coags, relevant imaging (MRI/CT/X-ray).
  • Informed Consent.
• Safety Essentials: "Time-out", Asepsis, Image guidance (US/Fluoroscopy), Radiation safety (ALARA).

⭐ A "Time Out" (correct patient, site, procedure) is MANDATORY before needle insertion.

Major Nerve Blocks - Pinpoint Relief

• Principle: Targeted delivery of local anesthetics (LA) ± corticosteroids near specific nerves or nerve plexuses for diagnosis or therapy.
• Guidance is Key: Fluoroscopy or Ultrasound essential for precision and safety.
• Key Procedures & Indications:
  • Epidural Steroid Injections (ESI): For radiculopathy, spinal stenosis.
    • Approaches: Interlaminar, Transforaminal (TFESI - more specific).
  • Facet Joint Interventions: For facet-mediated axial pain.
    • Diagnostic: Medial Branch Block (MBB).
    • Therapeutic: Radiofrequency Ablation (RFA) of medial branches.
  • Sympathetic Blocks: For CRPS, visceral pain.
    • Examples: Stellate ganglion, Lumbar sympathetic, Celiac plexus.
  • Major Peripheral Nerve Blocks: For specific neuralgias (e.g., occipital, genicular).
• Common Agents: LAs (Bupivacaine, Lidocaine), Steroids (Triamcinolone).
• Risks: Infection, hematoma, nerve injury, LA toxicity.

⭐ For facet joint pain, a positive response to two diagnostic medial branch blocks (MBBs) with >80% pain relief is typically required before proceeding to RFA.

Advanced Pain Therapies - Beyond Blocks

• Radiofrequency Ablation (RFA)
  • Mechanism: Thermal neurolysis via high-frequency current.
  • Types: Conventional (lesion at 80-90°C), Pulsed (non-destructive, neuromodulatory), Cooled (larger lesions).
  • Indications: Facet joint arthropathy, sacroiliitis, trigeminal neuralgia.
• Spinal Cord Stimulation (SCS)
  • Mechanism: Gate control theory modulation; paresthesia overlaps pain area.
  • Indications: Failed Back Surgery Syndrome (FBSS), Complex Regional Pain Syndrome (CRPS), refractory neuropathic pain.
  • Trial period essential before permanent implant.
• Intrathecal Drug Delivery Systems (IDDS)
  • Mechanism: Direct delivery of microdoses to CSF.
  • Indications: Severe cancer pain, intractable chronic non-malignant pain, spasticity (baclofen).
  • Common drugs: Morphine, ziconotide, baclofen.
• Peripheral Nerve Stimulation (PNS)
  • Targets specific peripheral nerves for mononeuropathies (e.g., occipital neuralgia).

⭐ Ziconotide, an N-type calcium channel blocker, is a non-opioid analgesic used in intrathecal pumps and does NOT cause respiratory depression.

Imaging & Pharmacology - See & Soothe

• Imaging Modalities:
  • Fluoroscopy: Real-time X-ray, needle guidance. AP, lateral, oblique views. Contrast (Iohexol) confirms spread. ⚠️ Radiation.
  • Ultrasound (USG): Real-time, no radiation. Visualizes nerves, vessels, soft tissues. Linear (superficial) & curvilinear (deep) probes.
• Pharmacological Agents:
  • Local Anesthetics (LAs): Reversibly block Na+ channels.
    • Amides (Lidocaine, Bupivacaine; 📌 two "i"s): Longer action. Max Lidocaine: 7 mg/kg (with epi).
    • Esters (Procaine, Chloroprocaine; 📌 one "i"): Shorter action, ↑allergy (PABA).
  • Corticosteroids: Potent anti-inflammatory.
    • Particulate (Methylprednisolone): Longer acting, ⚠️ embolic risk (avoid intravascular).
    • Non-particulate (Dexamethasone): Safer for high-risk vascular areas (transforaminal).
  • Contrast Media: Non-ionic iodinated (Iohexol) confirms placement, rules out intravascular uptake.

  ⭐ For Local Anesthetic Systemic Toxicity (LAST), esp. Bupivacaine cardiotoxicity, give Intralipid 20% (1.5 mL/kg bolus).

High‑Yield Points - ⚡ Biggest Takeaways

• Celiac plexus block: key for upper abdominal cancer pain (e.g., pancreatic).
• Stellate ganglion block: for upper limb CRPS, Raynaud's disease.
• Lumbar sympathetic block: for lower limb CRPS, phantom limb pain.
• Epidural Steroid Injections (ESI): for radicular pain; transforaminal approach common.
• Radiofrequency Ablation (RFA) of medial branches: for facet joint pain.
• Spinal Cord Stimulation (SCS): for Failed Back Surgery Syndrome (FBSS), refractory CRPS.
• Intrathecal pumps: for severe refractory cancer pain or chronic non-malignant pain.