Piriformis muscle injection using ultrasonography and motor stimulation--report of a technique.

The piriformis muscle syndrome has been described in the literature since 1947 and accounts for 6-8% of patients presenting with buttock pain, which may variably be associated with sciatica. Through the years, there have been attempts to find safe and effective ways of managing this condition, whether through conservative treatment or with the use of interventional procedures. Several authors have reported injection techniques using the following: nerve stimulation; fluoroscopy with electromyography; and fluoroscopy with muscle stimulation. We aim to describe an injection method which is effective, simple, reproducible, easily available, and safe. This is the first report on the combined use of ultrasonography and motor stimulation in performing piriformis muscle injection. Our technique offers advantages such as: markedly decreased radiation exposure for both patient and doctor; improved visualization of sciatic nerve and surrounding muscles; improved portability; the possibility of being performed as an office-based procedure; and allows for an accurate confirmation of pain in the piriformis muscle with stimulation.