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Chapter Summary
• Context: Cervical and lumbar spinal pain involves multiple potential anatomical pain generators, and interventional spinal procedures can serve diagnostic, prognostic, or therapeutic roles when applied to appropriately selected patients. Diagnostic block, prognostic test block, and therapeutic infiltration represent related but distinct concepts. A diagnostic block isolates the anatomical structure generating pain; a prognostic block predicts patient response to definitive neurotomy; and an infiltration primarily delivers local anti-inflammatory therapy. Fluoroscopy, computed tomography, and ultrasound guidance have markedly enhanced needle accuracy and procedural safety. Local anesthetics, corticosteroids (particulate vs non-particulate), and radiopaque contrast media require deep pharmacological familiarity to optimize efficacy and prevent catastrophic vascular complications. Radiofrequency technology provides thermal neurolysis, pulsed neuromodulation, or cooled lesioning for facet, sacroiliac, and discogenic pain syndromes. Crucially, interventional procedures never replace rigorous clinical diagnosis, nor should they delay surgical decompression in acute progressive neurological emergencies.
• Chapter Objective: To understand the foundational principles of spinal blocks and infiltrations, differentiate diagnostic from therapeutic indications, master pharmacological safety profiles (particulate vs non-particulate steroids, contrast dye verification), understand radiofrequency modalities (continuous thermal, pulsed, cooled), and identify clinical indications for facetogenic, radicular, discogenic, and sacroiliac pain.
• Define the primary objective firstThe chapter differentiates diagnostic blocks, test blocks, and therapeutic infiltrations. This distinction sharpens clinical interpretation and prevents misconstruing temporary local anesthetic relief as proof of permanent therapeutic efficacy.
• Pharmacology and patient safetyLocal anesthetics vary in onset, duration, and cardiotoxicity. Corticosteroids divide into particulate and non-particulate formulations—a vital distinction for preventing embolic spinal cord infarction during transforaminal injections. Contrast confirmation under live fluoroscopy or digital subtraction angiography identifies inadvertent intravascular uptake. Absolute contraindications include systemic sepsis, active coagulopathy, and progressive neurological deficits requiring surgical decompression.
• Targeted anatomical generatorsFacet joints, nerve roots, the sacroiliac joint, and the intervertebral disc require distinct anatomical targets. Clinical correlation must precede needle entry: injecting a degenerate structure seen incidentally on MRI without concordant physical pain reproduces diagnostic error.
• Radiofrequency modalitiesConventional continuous radiofrequency produces thermal neurolysis (80°C). Pulsed radiofrequency delivers high-voltage electric fields with temperatures ≤42°C for neuromodulation with minimal tissue destruction. Cooled radiofrequency enlarges lesion volume, useful for sacroiliac joint denervation. Medial branch neurotomy is indicated for facet pain, while pulsed RF near the dorsal root ganglion serves select radicular neuropathies.
• Procedural risks and complication managementTransient pain flares, paresthesias, direct neural trauma, vascular embolization, epidural hematoma, and infection represent potential adverse events. Safety depends on strict image guidance, non-particulate steroids in critical vascular zones, and preceding neurotomy with concordant diagnostic blocks.
• Clinical Application: In clinical practice, interventional procedures provide maximum value when answering a precise clinical question. In a patient with multi-level degenerative MRI findings, a selective diagnostic local anesthetic block clarifies which specific motion segment generates pain. In acute radiculopathy, a transforaminal epidural injection provides a therapeutic window to facilitate physical rehabilitation. Neurological red flags (cauda equina syndrome, progressive motor weakness) must be ruled out before intervening. Particulate steroids (e.g., triamcinolone, methylprednisolone) are strictly contraindicated in cervical and upper lumbar transforaminal injections due to the risk of radicular artery embolization and spinal cord stroke; non-particulate dexamethasone must be used. Radiofrequency facet denervation should never be performed based on MRI arthrosis alone: documented ≥50-80% pain relief following controlled medial branch blocks is mandatory before proceeding to thermal ablation.
