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Piriformis Syndrome: Differential Diagnoses & Workup

Author: Shishir Shah, DO, Consulting Staff, Comprehensive Woundcare, Banner Baywood Hospital
Coauthor(s): Thomas W Wang, MD, Consulting Staff, Department of Occupational Medicine, Kaiser-Permanente
Contributor Information and Disclosures

Updated: Apr 28, 2009

Differential Diagnoses

Hamstring Injury
Lumbosacral Spine Sprain/Strain Injuries
Lumbosacral Disc Injuries
Lumbosacral Spondylolisthesis
Lumbosacral Discogenic Pain Syndrome
Lumbosacral Spondylolysis
Lumbosacral Facet Syndrome
Sacroiliac Joint Injury
Lumbosacral Radiculopathy

Other Problems to Be Considered

  • Bursitis or weaver's bottom (ie, ischiogluteal bursitis)
  • Gout
  • Pelvic mass, tumor, or endometriosis (in women)
  • Referred pain to the buttock caused by pronator forces of the foot
  • Sciatica caused by compression secondary to a fibrotic band, hematoma, or aneurysm of the inferior or superior gluteal artery
  • Spinal stenosis

Workup

Imaging Studies

  • Computed tomography (CT) scanning
    • CT scans may demonstrate a large mass anterior to the piriformis muscle.
    • More importantly, CT scans can be used to identify spinal stenosis or arthritic changes.
  • Magnetic resonance imaging (MRI)
    • MRI findings can rule out other causes of back pain, such as a herniated disc, spinal tumor, or abscess.
    • The piriformis muscle also can appear enlarged on T1- or T2-weighted images.
  • Electromyography (EMG)
    • EMG can also be performed to determine neurologic or muscular changes.
    • In piriformis syndrome, EMG findings in the gluteus minimus, gluteus medius, and tensor fasciae latae muscles are normal.
    • In piriformis syndrome, abnormal patterns are found in the gluteus maximus and piriformis muscles.
    • In the case of a herniated disc, all muscles that are posteriorly and anteriorly innervated should be affected.
    • With a herniated disc, a significant delay in the Hoffman reflex, or H-reflex (motor nerve fiber response after activation of afferent sensory spindle fibers), in the affected limbs is often present during EMG.

Procedures

  • Diagnostic injection of the piriformis syndrome trigger point is performed as follows:
    • Localize the pain at the sciatic notch, transvaginally or transrectally.
    • Draw 5-7 mL of 2.5% lidocaine or bupivacaine into a 10-mL syringe with a 27-gauge needle.
    • Prepare a sterile field and apply Betadine over the trigger-point area.
    • Inject the anesthetic after aspirating to confirm that the needle is not in a vascular bundle.
    • Remove the needle, and apply pressure to the area to ensure hemostasis.
    • Allow the patient to ambulate and to abduct and externally rotate the affected leg.
    • If the pain subsides, the likely cause of the pain is piriformis syndrome.
    • This procedure is both therapeutic and diagnostic.

More on Piriformis Syndrome

Overview: Piriformis Syndrome
Differential Diagnoses & Workup: Piriformis Syndrome
Treatment & Medication: Piriformis Syndrome
Follow-up: Piriformis Syndrome
References
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References

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  3. Boyajian-O'Neill LA, McClain RL, Coleman MK, Thomas PP. Diagnosis and management of piriformis syndrome: an osteopathic approach. J Am Osteopath Assoc. Nov 2008;108(11):657-64. [Medline]. [Full Text].

  4. [Best Evidence] Naja Z, Al-Tannir M, El-Rajab M, et al. The effectiveness of clonidine-bupivacaine repeated nerve stimulator-guided injection in piriformis syndrome. Clin J Pain. Mar-Apr 2009;25(3):199-205. [Medline].

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  11. Naja Z, Al-Tannir M, El-Rajab M, et al. The effectiveness of clonidine-bupivacaine repeated nerve stimulator-guided injection in piriformis syndrome. Clin J Pain. Mar-Apr 2009;25(3):199-205. [Medline].

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  16. Pecina HI, Boric I, Smoljanovic T, Duvancic D, Pecina M. Surgical evaluation of magnetic resonance imaging findings in piriformis muscle syndrome. Skeletal Radiol. Nov 2008;37(11):1019-23. [Medline].

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  19. Tibor LM, Sekiya JK. Differential diagnosis of pain around the hip joint. Arthroscopy. Dec 2008;24(12):1407-21. [Medline].

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Further Reading

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Keywords

piriformis syndrome, hip pocket neuropathy, sciatic neuritis, wallet neuritis, lower back pain, low back pain, LBP, periarthritis of the anterior sacroiliac joint, piriformis muscle, piriformis hypertrophy, sciatic nerve entrapment, herniated nucleus pulposus, muscle spasm due to chronic or overuse injury, sciatica, Morton foot, spinal stenosis, nerve entrapment syndromes

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Contributor Information and Disclosures

Author

Shishir Shah, DO, Consulting Staff, Comprehensive Woundcare, Banner Baywood Hospital
Shishir Shah, DO is a member of the following medical societies: American Academy of Family Physicians, American Medical Association, and American Osteopathic Association
Disclosure: Nothing to disclose.

Coauthor(s)

Thomas W Wang, MD, Consulting Staff, Department of Occupational Medicine, Kaiser-Permanente
Thomas W Wang, MD is a member of the following medical societies: American Academy of Family Physicians
Disclosure: Nothing to disclose.

Medical Editor

Joseph P Garry, MD, FACSM, FAAFP,, Director of Sports Medicine and Sports Medicine Fellowship, Associate Professor of Family Medicine and Exercise and Sport Science, Department of Family Medicine, East Carolina University Brody School of Medicine
Joseph P Garry, MD, FACSM, FAAFP, is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, American Heart Association, American Medical Society for Sports Medicine, and North American Primary Care Research Group
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Russell D White, MD, Professor of Medicine, Department of Community and Family Medicine, University of Missouri-Kansas City School of Medicine, Truman Medical Center Lakewood
Disclosure: Nothing to disclose.

CME Editor

Jon B Whitehurst, MD, Clinical Instructor of Surgery, University of Illinois College of Medicine; Partner and Executive Board Member, Rockford Orthopedic Associates; Orthopedic Chairman, Rockford Memorial Hospital
Jon B Whitehurst, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America
Disclosure: Nothing to disclose.

Chief Editor

Sherwin SW Ho, MD, Associate Professor, Department of Surgery, Section of Orthopedic Surgery and Rehabilitation Medicine, University of Chicago
Sherwin SW Ho, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Society for Sports Medicine, and Arthroscopy Association of North America
Disclosure: Nothing to disclose.

 
 
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