This is the first study to report the results of using ultrasound (US) to guide needle injection of the piriformis muscle (PM). The PM is located deep in the buttock and can cause painful buttock or hip symptoms along with sciatica.
Sciatica refers to irritation of the sciatic nerve from any cause. In the case of piriformis syndrome, it's likely the PM is compressing or contracting around the sciatic nerve. A steroid injection into the PM can help ease the symptoms and restore pain free hip and leg motion.
In the past, physicians have used electromyography, CT, MRI, and fluoroscopy to guide the needle injection. Fluoroscopy is a special X-ray technique that gives the doctor a real-time image of the body part in question. Researchers at the Mayo Clinic in Rochester, Minnesota studied steroid injection of the piriformis using ultrasound imaging instead.
US has several advantages over other imaging methods. It does not expose the patient to any X-rays. US gives a clear image of each layer of soft tissue. The physician is able to advance the needle right to the sheath or lining of the piriformis. The steroid drug can be injected into the sheath or directly into the muscle.
Today's US machines are compact making this an easy-to-apply diagnostic test and treatment. Physicians already trained in US techniques can learn how to perform this treatment technique in one day.
The authors of this article provide detailed step-by-step instructions with ultrasound photos to help the reader in this process.
Jay Smith, MD, et al. Ultrasound-Guided Piriformis Injection: Technique Description and Verification. In Archives of Physical Medicine and Rehabilitation. December 2006. Vol. 87. No. 12. Pp. 1664-1667.'