Ultrasound guided piriformis injection with confirmation of needle placement through electromyography: a case report and description of a new technique

Abstract

A 60 year old male presented to our clinic with lower back, left hip and left buttocks pain for 6 years. The pain was sharp in quality, and radiated toward the left lateral buttock and hip. The pain was rated 6/10, and aggravated by prolonged sitting, squatting, and bending over. On examination, the patient demonstrated tenderness along left lumbar paraspinals and lateral buttocks area. Straight leg raise and FAIR test was positive in LLE. Prior electromyography exam demonstrated a left L5 motor radiculopathy. L-spine MRI revealed multilevel degenerative disc disease. Having previously failed conservative treatment, including PT and gabapentin, a caudal epidural was performed. The patient reported no improvement in his symptoms after the injection. Upon further assessment, diagnosis of piriformis syndrome was considered. A diagnostic injection of lidocaine was performed under ultrasound and EMG guidance into the piriformis muscle. After the injection, the patient had relief of pain. One of the main treatments of piriformis syndrome is injection of local anesthetic or steroids into the piriformis muscle belly. Due to difficulty with needle placement, previous authors have reported various methods in performing piriformis injections: fluoroscopically, motor stimulation, and most recently, ultrasound guidance. With ultrasound alone, even with visualization of needle placement, it is difficult to ensure needle insertion into the piriformis muscle, as opposed to surrounding muscles, specifically the gluteus medius and gluteus maximus. To our knowledge, this is the first report of combined use of ultrasound with EMG confirmation of needle placement for a piriformis injection. Our technique offers the advantage of decreased radiation exposure when compared to fluoroscopy and verification of needle placement into the piriformis when compared to injections without EMG. In addition, our case presentation emphasizes the ability for piriformis syndrome to mimic other diagnosis. A 60 year old male presented to our clinic with lower back, left hip and left buttocks pain for 6 years. The pain was sharp in quality, and radiated toward the left lateral buttock and hip. The pain was rated 6/10, and aggravated by prolonged sitting, squatting, and bending over. On examination, the patient demonstrated tenderness along left lumbar paraspinals and lateral buttocks area. Straight leg raise and FAIR test was positive in LLE. Prior electromyography exam demonstrated a left L5 motor radiculopathy. L-spine MRI revealed multilevel degenerative disc disease. Having previously failed conservative treatment, including PT and gabapentin, a caudal epidural was performed. The patient reported no improvement in his symptoms after the injection. Upon further assessment, diagnosis of piriformis syndrome was considered. A diagnostic injection of lidocaine was performed under ultrasound and EMG guidance into the piriformis muscle. After the injection, the patient had relief of pain. One of the main treatments of piriformis syndrome is injection of local anesthetic or steroids into the piriformis muscle belly. Due to difficulty with needle placement, previous authors have reported various methods in performing piriformis injections: fluoroscopically, motor stimulation, and most recently, ultrasound guidance. With ultrasound alone, even with visualization of needle placement, it is difficult to ensure needle insertion into the piriformis muscle, as opposed to surrounding muscles, specifically the gluteus medius and gluteus maximus. To our knowledge, this is the first report of combined use of ultrasound with EMG confirmation of needle placement for a piriformis injection. Our technique offers the advantage of decreased radiation exposure when compared to fluoroscopy and verification of needle placement into the piriformis when compared to injections without EMG. In addition, our case presentation emphasizes the ability for piriformis syndrome to mimic other diagnosis.