Interventional Pain Procedures
Safety fundamentals
Most procedures use fluoroscopy or ultrasound. Know the target, the laterality, and the structures at risk before the needle goes in. Confirm needle position with contrast before injecting: vascular uptake or unexpected intrathecal spread changes the plan. Coagulation status matters most for neuraxial procedures (epidural, spinal); follow guideline intervals for anticoagulants and antiplatelet agents.
Common procedures
Epidural steroid injection can be interlaminar (loss-of-resistance), transforaminal, or caudal. Trap: cervical transforaminal epidural injection risks vertebral artery or spinal cord infarction, and non-particulate steroid is preferred. Facet-mediated pain is diagnosed with medial branch blocks-two levels must be blocked for each facet joint-and treated with radiofrequency ablation only when diagnostic blocks produce substantial relief. Sympathetic blocks: stellate ganglion block produces an ipsilateral Horner syndrome; lumbar sympathetic block produces a warm, dry leg. Trigger point injections typically use local anesthetic, not steroid.
Complications
Epidural hematoma presents with progressive back pain and new deficit after a neuraxial procedure and requires urgent MRI. Other risks include infection, postural headache from dural puncture, and local anesthetic systemic toxicity-treated with airway support, seizure control, and 20% lipid emulsion. Steroid effects include hyperglycemia, adrenal suppression, and flushing.
Worked example
A patient develops rapidly worsening leg weakness and urinary retention hours after a lumbar transforaminal epidural steroid injection. This is not a "steroid flare"; obtain urgent MRI to exclude epidural hematoma or abscess and involve spine surgery.
Rule of thumb: before any neuraxial procedure, confirm four things-coagulation status, consent, contrast confirmation, and a post-procedure neurologic check plan.