March 9, 2020 e-Pearl of the Week: Piriformis syndrome

Piriformis syndrome

Piriformis syndrome is an entrapment neuropathy characterized by buttock pain that increases within 15-20 minutes of sitting (positive wallet sign). Crural weakness, dyspareunia, and painful defecation with positive Freiberg sign—pain experienced during passive internal rotation of the hip—and Pace sign—recreation of sciatic-like symptoms with flexion, abduction, and internal rotation of the hip-FAIR test—are the clinical hallmarks.1,3 Incidence is 0.3 to 6% of all sciatic-like syndromes.2 Pathophysiology involves entrapment of the sciatic nerve by a bifid piriformis muscle or nerve irritation by fibrosis. MRI may reveal hypertrophy/atrophy, fibrosis, and anomalous insertion of the piriformis muscle and help exclude other etiologies; NCS shows increased H reflex latency with FAIR-test, while EMG shows signs of denervation in the pattern of the posterior tibial or peroneal nerve. Differential includes a lumbosacral radiculopathy, sacroiliac joint dysfunction, or hamstring injury.  Treatment options include NSAIDs, muscle relaxants, physical therapy, botulinum toxin and steroid injection. Piriformis tenotomy is considered for refractory cases.3

References

  1. Foster MR. Piriformis syndrome. Orthopedics. 2002;25:821–825.
  2. Byrd JW. Piriformis syndrome. Oper Tech in Sports Med 2005;13:71–79.
  3. Magee DJ. Orthopedic Physical Assessment, 3rd ed. Philadelphia: WB Saunders; 1997.

Tanay Satarkar, Medical Graduate, Bukovinian State Medical University (Chernivstki, Ukraine) and Faisal Khan, MD, DABSM, DABPN, Consultant Neurologist, Sugar Land Neurology and Sleep (Sugar Land, Texas)

Tanay Satarkar and Dr. Khan report no disclosures.