Sacral Nerve Root Block



Sacral Nerve Root Block


Donald V. La Barge, III, MD










Sagittal T2WI MR shows multiple thin-walled cysts image within the sacral canal and enlarged neural foramina. Note displacement of the dorsal root ganglia (DRG) peripherally image.






Axial post-contrast fat-saturated T1 MR image again shows multiple thin-walled cysts image within the sacral canal and enlarged neural foramina displacing the normally enhancing DRG peripherally image.


TERMINOLOGY


Abbreviations



  • Nerve root block (NRB)


Synonyms



  • Sacral selective nerve root injection


Definitions



  • Selective corticosteroid and long-acting anesthetic injection of a sacral nerve root at the level of neural foramen


PRE-PROCEDURE


Indications



  • Radiculopathy corresponding to sacral nerve root dermatome


  • Acute or chronic sacral radiculopathy


  • Osteoarthritis


  • Compression of sacral nerve root



    • Malignant or benign neoplasm


    • Perineural cyst


Contraindications



  • Coagulopathy


  • Allergy to components of injectate


  • Local or systemic infection


  • Relative



    • Allergy to iodinated contrast


    • Pregnancy


    • Recent live virus vaccination


Getting Started



  • Things to check



    • Pre-procedure imaging



      • Evaluate relevant anatomic landmarks


      • Search for other causes of patient’s pain


    • Laboratory data



      • Evidence of infection or impaired coagulation


    • Informed consent


  • Medications



    • Short-acting (local) anesthetic


    • Long-acting anesthetic


    • Corticosteroid


    • Myelography-safe radiographic contrast


  • Equipment list



    • Radiopaque marker


    • Sterile prep and drape materials


    • 5 mL syringe and 1.5 inch 25-gauge needle for local anesthetic


    • 5 mL syringe and extension tubing for radiographic contrast


    • 3 mL syringe for injectate



      • Usual injection volume is ˜ 2 mL


    • 22-gauge spinal needle


    • Hydrogen peroxide



      • Skin cleanser


    • Bandage


PROCEDURE


Patient Position/Location



  • Best procedure approach



    • Prone



      • Angle of C-arm depends on lumbosacral lordosis


Equipment Preparation



  • Draw 5 mL of local anesthetic, and attach 1.5 inch 25-gauge needle


  • Draw 5 mL of myelography-safe contrast, and preload extension tubing



    • Tubing should be air-free


  • Draw injectate



    • Generally 2 mL (e.g., 1 mL [80 mg] methylprednisolone + 1 mL 0.5% bupivacaine)


Procedure Steps



  • Procedure “time out”



    • Correct patient, procedure, and side


    • All necessary equipment present


  • Angle C-arm to obtain optimal visualization of targeted sacral neural foramen



    • Often only minimal angulation is necessary


  • Mark skin


  • Perform sterile prep and drape



  • Create skin wheal with local anesthetic, and anesthetize subcutaneous tissues


  • Anchor 22-gauge spinal needle in subcutaneous tissue, and confirm trajectory with fluoroscopy



    • Right side: Target foramen at 1-2 o’clock


    • Left side: Target foramen at 10-11 o’clock


  • Carefully advance spinal needle under intermittent fluoroscopy until intraforaminal or bone is reached


  • If bone is reached, carefully “walk” needle into upper outer quadrant of foramen

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Sep 22, 2016 | Posted by in EMERGENCY RADIOLOGY | Comments Off on Sacral Nerve Root Block
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