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.



  • Nerve root block (NRB)


  • Sacral selective nerve root injection


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



  • Radiculopathy corresponding to sacral nerve root dermatome

  • Acute or chronic sacral radiculopathy

  • Osteoarthritis

  • Compression of sacral nerve root

    • Malignant or benign neoplasm

    • Perineural cyst


  • 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


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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