Piriformis Steroid Injection



Piriformis Steroid Injection


Donald V. La Barge, III, MD










Red, swollen sciatic nerve image passes through the sciatic notch in this patient with compressive neuropathy caused by an enlarged piriformis muscle. The gluteal musculature has been cut away image.






Coronal T1 MR image shows sciatic nerve fibers image on either side of the piriformis muscle. This is the most common anomalous course of the sciatic nerve, which may predispose patients to the piriformis syndrome.


TERMINOLOGY


Definitions



  • Selective image-guided injection of long-acting anesthetic and corticosteroid into piriformis muscle adjacent to sciatic nerve in treatment of piriformis syndrome



    • Some advocate intramuscular botulinum toxin A injection


PRE-PROCEDURE


Indications



  • Piriformis syndrome



    • Buttock and leg pain (one of a myriad of causes of sciatica)



      • Hypertrophied piriformis muscle



        • Strong hip adductors, weak abductors


      • Post-traumatic



        • Often sequelae of a fall injury, fibrosis


      • Also seen in cases of pyomyositis, dystonia musculorum deformans, and fibrosis related to prior injections


  • Sciatic notch pain


  • Injection is generally reserved for cases in which conservative measures/physical therapy have failed


Contraindications



  • Coagulopathy


  • Systemic infection


  • Known severe allergy to components of injectate


  • Relative



    • Pregnancy



      • Teratogenic effects of ionizing radiation


      • Can be performed with ultrasound guidance


Getting Started



  • Things to check



    • Pre-procedure imaging



      • Look for signs of lumbosacral plexus compression



        • Herniated lumbar disc


        • Osteoarthritis of lumbosacral spine


        • Osteoarthritis of facet joints


        • Tumor


      • Evaluate sacroiliac (SI) joints



        • Sacroiliitis


        • Osteoarthritis


      • Rule out hip joint abnormality



        • Osteoarthritis


        • Femoroacetabular impingement


      • Evaluate for pelvic musculature abnormality/ asymmetry



        • Hypertrophic piriformis muscle


    • Laboratory data



      • Coagulation parameters



        • Prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR)


        • Hemoglobin (Hb), hematocrit (Hct), and platelets


      • Infection/inflammation markers



        • White blood cells (WBC), c-reactive protein (CRP), erythrocyte sedimentation rate (ESR), temperature


    • Informed consent


  • Medications



    • Short-acting anesthetic


    • Long-acting anesthetic


    • Corticosteroid


    • Iodinated contrast (if desired)


  • Equipment list



    • Sterile prep and drape materials


    • Radiopaque skin marker


    • 5 mL syringe with long 25-gauge needle for local anesthetic


    • 3 mL syringe for injectate


    • 10 mL syringe with extension tubing if contrast injection is desired


    • 20-22-gauge spinal needle


    • Hydrogen peroxide



      • Skin cleanser after the procedure


    • Bandage


    • Nerve stimulator may further assist in confirming needle tip placement prior to injection



PROCEDURE


Patient Position/Location



  • Best procedure approach



    • Prone


    • Fluoroscopy



      • Identify a line connecting inferior aspect of sacroiliac joint and superolateral margin of acetabulum


      • Optimal target is 1/3 of distance from superolateral acetabulum along that line (2/3 of distance away from SI joint)


    • Computed tomography (CT)

Sep 22, 2016 | Posted by in EMERGENCY RADIOLOGY | Comments Off on Piriformis Steroid Injection
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