Background & Aims

Piriformis syndrome is an uncommon and underdiagnosed condition, which may be described as pain in the lower back, buttock and upper posterior thigh. It is caused by compression of the sciatic nerve by the overlying piriformis muscle at the level of the ischial tuberosities. The prevalence of piriformis syndrome ranges from 6.3% in rehabilitation medicine and orthopedic settings, to 17.2% in pain clinics.

Arriving at a definite diagnosis of piriformis syndrome is difficult because at present, there is no gold standard test. Many diagnostic criteria based on clinical signs and symptoms have been created to aid in diagnosis. Diagnostic image-guided injection of the piriformis muscle allows for more accurate injection into the target site, and indicates a correct diagnosis. This study primarily aims to compare the accuracy of the presence of clinical features included in the diagnostic criteria of piriformis syndrome, using a positive ultrasound-guided piriformis injection as basis.

Methods

This study is a retrospective cohort. Medical records of patients diagnosed with piriformis syndrome from the Siriraj Hospital Pain Management Center from December 2016 to February 2023 were reviewed.
Patients aged 18 and older clinically diagnosed with piriformis syndrome were included. These clinical features were noted 1) hip/buttock and/or leg pain, 2) pain aggravated by sitting, 3) FAIR (flexion, adduction, internal rotation) test result, and 4) tenderness over the area of the piriformis muscle. They should have also received an ultrasound-guided piriformis muscle diagnostic injection.
Data collected from medical records included patients’ demographics, symptoms related to piriformis syndrome, pain description, physical examination results, and treatments for piriformis syndrome. Details of the ultrasound-guided piriformis block, duration, and pain scores based on an 11-point numerical rating scale (0=no pain,10=worst pain imagined),before and after the block were also recorded.

Results

Preliminary results included records of 126 patients with a mean age of 63.81 +- 15.03 years. All patients presented with buttock pain. Thirty-five percent of patients who had a positive response to an ultrasound-guided piriformis block had pain aggravated by sitting. Almost all patients (94.8%) who had a positive ultrasound-guided piriformis block had tenderness over the area of the piriformis muscle. Eighty-seven percent of patients with a positive block had a positive FAIR test.

Conclusions

Buttock pain, tenderness over the area of the piriformis muscle, and positive FAIR test had a high accuracy of diagnosing piriformis syndrome.

References

[1] N. Viji, H. Kiernan, R. Bisht, I. Singleton, E. M. Cornett, A. D. Kaye, F. Imani, G. Varrassi, M. Pourbahri, O. Viswanath and I. Urits, “Surgical and non-surgical treatment options for piriformis syndrome: a literature review,” Anesthesiology and pain medicine, vol. 11, no. 1, 2021.
[2] B. L. Hicks, J. C. Lam and M. Varacallo, Piriformis syndrome, Treasure Island, Florida: StatPearls Publishing, 2023.
[3] J. W. Park, Y. J. Lee, S. Shin, Y. Kang and K. Koo, “Deep gluteal syndrome as a cause of posterior hip pain and sciatica-like pain,” Bone and joint journal, pp. 556-557, 2020.
[4] U. S. Singh, R. K. Meena, C. K. Singh, A. M. Singh and R. Langshong, “Prevalence of piriformis syndrome among the cases of low back / buttock pain with sciatica: a prospective study,” Journal of the Society of Medicine, 2013.
[5] F. Michel, P. Decavel, E. Toussirot, L. Tatu, E. Aleton, G. Monnier, P. Garbuio and B. Parratte, “Piriformis muscle syndrome: diagnostic criteria and treatment of a monocentric series of 250 patients,” Annals of Physical and Rehabilitation Medicine, pp. 371-383, 2013.
[6] M. Kaga and T. Ueda, “Effectiveness of hydro-dissection of the piriformis muscle plus low-dose local anesthetic injection for piriformis syndrome: a case report of 2 cases,” American Journal of Case Reports, vol. 23, pp. e935326-1-e935246-6, 2022.
[7] S. Cass, “Piriformis syndrome: a cause of nondiscogenic sciatica,” Current sports medicine reports, vol. 1, pp. 41-44, 14.
[8] D. Probst, A. Stout and D. Hunt, “Piriformis syndrome: a narrative review of the anatomy, diagnosis and treatment,” Physical Medicine and Rehabilitation, vol. 11, no. 2019, pp. S54-63, 2019.
[9] R. M. Frank, M. A. Slabaugh and R. C. Grumet, “Posterior hip pain in an athletic population: differential diagnosis and treatment options,” Sports Health, vol. 2, no. 3, pp. 237-246, 2010.
[10] H. D. Martin, B. R. Kivlan, I. J. Palmer and R. L. Martin, “Diagnostic accuracy of clinical tests for sciatic nerve entrapment in the gluteal region,” Knee surgery, sports traumatology arthroscopy, vol. 22, no. 4, pp. 882-888, 2014.
[11] H. T. Benzon, J. A. Katz, H. A. Benzon and M. S. Iqbal, “Piriformis syndrome: anatomic considerations, a new injection technique and a review of the literature,” Anesthesiology, vol. 98, pp. 1442-8, 2003.
[12] K. Hopayian and A. Danielyan, “Four symptoms define the piriformis syndrome: an updated systematic review,” European Journal of Orthopaedic Surgery and Traumatology, vol. 28, pp. 155-164, 2017.
[13] K. Hopayian, F. Song, R. Rier and S. Sambandan, “The clinical features of the piriformis syndrome: a systematic review,” European Spine Journal, vol. 19, pp. 2095-2109, 2010.
[14] L. M. Fishman, G. W. Dombi and C. Michaelsen, “Piriformis syndrome:diagnosis, treatment and outcome – a 10 year study,” Archives of Physical Medicine and Rehabilitation, vol. 83, pp. 295-301, 2002.
[15] Y. Wu, X. Guo, K. Chen, F. He and J. Quan, “Feasibility and reliability of an ultrasound examination to diagnose piriformis syndrome,” World Neurosurgery, vol. 134, pp. e1085-e1092, 2020.
[16] G. G. Gulec, K. K. Oktay, I. Aktas and B. Yilmaz, “Visualizing anatomic variants of the sciatic nerve using diagnostic ultrasound piriformis muscle injection: an example of 4 cases,” Journal of Chiropractic Medicine, vol. 21, no. 3, pp. 213-219, 2022.
[17] D. Jankovic, P. Peng and A. van Zundert, “Brief review: piriformis syndrome: etiology, diagnosis, and management,” Canadian Journal of Anaesthesiology, 2013.

Presenting Author

Suratsawadee Wangnamthip

Poster Authors

Nina Johanna Antoine Lim

Doctor of Medicine

Lead Author

E-mail

Topics

  • Specific Pain Conditions/Pain in Specific Populations: Neuropathic Pain - Peripheral