Peripheral Nerve Blocks: A Color Atlas
2nd Edition

56
Myoneural Injections
Nashaat N. Rizk
Albert J. Carvelli
Patient Position: Prone on fluoroscopy table.
Indications: Myofascial pain in muscle groups secondary to areas of ischemia in those muscles as a result of reflex muscle and vascular spasm. This is often secondary to prolonged imbalance in posture from chronic low back pain.
Needle Size: 22-gauge 88-mm Quincke spinal needle.
Medication/Volume: 0.25 to 0.5% bupivacaine, 10 mL per muscle group. Decrease the dose by 20% if more than one group is injected.
Anatomic Landmarks:
  • Piriformis injection: The muscle attached proximally to the anterior border of the sacrum and distally to the superior border of the greater trochanter of the femur. Under fluoroscopy in the anteroposterior view, identify the greater trochanter, the head of the femur, and the neck of the femur.
  • Quadratus lumborum injection: The muscle is attached superiorly to the inferior border of the 12th rib and inferiorly to the internal lip of the iliac crest. Under fluoroscopy in the anteroposterior view, identify the iliac crest in the lumbar back.
  • Psoas muscle injection: The proximal attachment is the sides of T12-L5 vertebrae, and the distal attachment is the lesser trochanter of the femur. Under fluoroscopy in the anteroposterior view, identify the L3 vertebral body and transverse process.
Technique and Approach:
  • Piriformis injection: Identify the landmarks as listed previously. Direct a 22-gauge spinal needle just superior to the neck of the femur, medial to the greater trochanter, and lateral to the head of the femur. The injection of 2 mL Isovue-200 (Bracco Diagnostics, Princeton, NJ) dye shows the piriformis muscle as a distinct band running in the direction of the sacrum to the greater trochanter (Fig. 56-1. After negative aspiration for blood, the local anesthetic mixture is injected.
  • Quadratus lumborum injection: After identification of the iliac crest in the lumbar back region, insert a 22-gauge needle until it comes into contact with the superior edge of the iliac crest. Walk the needle off the iliac crest until it lies just superior and 1 cm deep to the bone (Fig. 56-2A. Inject 1 to 2 mL Isovue-200 to rule out intravascular placement of the needle. After negative aspiration for blood, the local anesthetic mixture is injected.
  • Psoas muscle injection: After identification of the L3 vertebral body and transverse process, insert a 22-gauge needle so that the tip is just inferior and deep to the transverse process at this level. Inject 2 mL of Isovue-200 to reveal the muscle as it fans out from the vertebral body inferiorly and laterally (Fig. 56-2B. After negative aspiration for blood, the local anesthetic mixture is injected.
    FIG. 56-1.
    FIG. 56-2.
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TIPS
  • If the course of the muscle is not delineated after injection of the dye, but rather appears blotchy, the needle will need to be repositioned.
  • Botox (Allergen, Irvine, CA) 25 to 100 U can be injected after a successful diagnostic block is performed. The dose depends on the intensity of the patient’s pain.
SUGGESTED READINGS
Sola AE, Bonica JJ. Myofascial pain syndromes. In: Loeser JD, ed. Bonica’s management of pain, 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2001.