PR_136: Piriformis Injection Using Ultrasound Guidance: Description and Validation of Technique

Abstract

Setting: Tertiary care medical center. Program: Ultrasound-guided piriformis injection. Program Description: Piriformis syndrome is a painful condition consisting of gluteal, hip, and variable leg pain similar in presentation to lumbosacral radiculopathy. Piriformis syndrome may be responsible for up to 6% to 8% of low back pain and sciatica. Due to lack of a criterion standard, diagnosis can be difficult and is often one of exclusion. Piriformis muscle and/or sheath injections are often used diagnostically (anesthetic) and/or therapeutically (eg, corticosteroid, botulinum toxin). Although “blind” piriformis muscle injections are performed, guidance is recommended for accurate localization. Techniques utilizing magnetic resonance imaging, computed tomography, fluoroscopy, electromyography, and nerve stimulator guidance have been well described. Ultrasound (US) offers an alternative means for accurate placement of piriformis injections, with several distinct advantages over traditional guidance techniques. We present an easy to learn method using US guidance to inject the piriformis, with fluoroscopic validation. Assessment/Results: We utilized office-based US equipment to reliably identify the piriformis using bony acoustic landmarks. Piriformis muscle and/or sheath injections could be precisely placed while avoiding adjacent neurovascular structures, as confirmed by fluoroscopic imaging of contrast injected with US placement. Discussion: Successful piriformis injection is important for diagnostic and therapeutic purposes in patients with presumed piriformis syndrome. US identifies relevant bony and soft tissue structures and provides guidance for accurate piriformis injection. Furthermore, US provides several distinct advantages over traditional guidance techniques. Conclusions: Piriformis injection under US guidance provides a highly accurate, real-time, cost-effective technique with no radiation exposure that can be performed by the physiatrist in an office setting.