Piriformis Syndrome

Abstract

Piriformis muscle is an uncommon cause of back and radicular pain. In the realm of radicular pain, piriformis syndrome is often overlooked. The diagnosis is difficult due to long list of causes that can cause gluteal and leg pain. It is classically described as a neuritis of the sciatic nerve caused by compression or irritation of the nerve by the piriformis muscle (Cass Curr Sports Med Rep 14:41–4, 2015; Hopayian and Danielyan Eur J Orthop Surg Traumatol 28:155–164, 2017; Smoll Clin Anat 23:8–17, 2010; Benzon et al. Anesthesiology 98:1442–8, 2003; Jawish et al. J Orthop Surg Res 5:3, 2010). Piriformis syndrome can be caused by anatomic variations (Benzon et al. Anesthesiology 98:1442–8, 2003) of the sciatic nerve course related to the closely proximate piriformis muscle, anatomic variations of the piriformis muscle itself, or traumatic incidents. The most common cause is macrotrauma (Jawish et al. J Orthop Surg Res 5:3, 2010), which leads to muscle spasm and resultant soft tissue inflammation. There is no one specific test to treat for piriformis syndrome, but rather the entity is best considered as a diagnosis of exclusion. Fusing the history and a constellation of physical examination tests can help cinch the syndrome as the putative cause of pain. Tests such as the Freiberg, Pace, FABER, FAIR, and Beatty tests, which show deep buttock pain, can demonstrate a hypertrophied or taught piriformis muscle (Jawish et al. J Orthop Surg Res 5:3, 2010). Additional studies, including neurophysiologic testing, CT, MR, and ultrasound, can be used in the diagnosis, especially as mechanism to rule out other confounding diagnosis, including sacroiliac pain, hip bursitis, degenerative disc disease, and lumbosacral radiculopathies, among others.

The mainstay of treatment is rest and analgesics, including therapies from NSAIDs, acetaminophen, gabapentin, muscle relaxants to opiates. Additionally a physical therapy program containing elements including heat/cold therapy, TENs, and ultrasound massage to strengthen surrounding muscles as well as stretch and relax the piriformis muscle is a critical component to recovery. If resistant to conservative management, more invasive treatments, including ultrasound-guided trigger point injections of local anesthetic and steroids as well as botulinum toxin injections, have been shown to be effective in temporarily relieving the pain. Ultimately some patients can require surgical release of the piriformis muscle to relieve impingement on the sciatic nerve.