The internal obturator muscle may cause sciatic pain

Abstract

Six patients suspected to have piriformis syndrome were operated in the hip region in an attempt to relieve pressure on the sciatic nerve. The piriformis muscle and tendon as well as their relationship to the sciatic nerve were found to be normal. However, the internal obturator muscle was found to be very tense, slightly hyperaemic and pressing the sciatic nerve. During Lasegue's testing on the operating table the internal obturator and not the piriformis muscle impinged on the nerve at an early stage in the hip flexion movement. A sectioning of the tendon to the internal obturator muscle near its insertion at the trochanter was performed. Median pain score was found to be reduced from the preoperative value (8.5) to that at 6 weeks (3.5) (P<0.05) and 3 (3.5) (P<0.05) and 6 months (5.5) (N.S.) postoperatively. No significant reduction of pain was found in a control group of six patients followed during the same period. Three patients who needed opioids preoperatively managed without such drugs 6 months after the operation. Two patients in the operated group were at work 50 and 100% after having been out of work for 3 and 10 years, respectively.

Posterior, Lateral, and Anterior Hip Pain Due to Musculoskeletal Origin: A Narrative Literature Review of History, Physical Examination, and Diagnostic Imaging

“…45 Similarly, tendinopathy of the obturator internus/gemelli complex of muscles can mimic piriformis syndrome and produce retro-trochanteric pain. 49,50 Again, definitive imaging findings have yet to be established. The only deep external rotator to have predictable diagnostic imaging findings when pathology is present is the quadratus femoris muscle.…”

Brief review: Piriformis syndrome: etiology, diagnosis, and management

“…1 The piriformis muscle (1) and neighboring muscles, nerves, and vessels: 2, gluteus minimus; 3, gluteus medius; 4, gluteus maximus; 5, quadratus femoris; 6, superior gluteal nerve; 7, inferior gluteal nerve; 8, posterior cutaneous femoral nerve; 9, superior gluteal artery; 10, inferior gluteal artery and vein; 11, internal pudendal artery 91 vicinity. They are the small external rotators of the hip (obturator internus, in particular, because it is partly an intrapelvic muscle and partly a hip muscle) 7,31 and the hamstring muscles (through activation and perpetuation of trigger points). 7,32 The neuropathic component refers to the compression or irritation of the sciatic nerve as it courses through the infrapiriform foramen.…”

Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria)

“…14,15 Central hypersensitivity phenomena can also be involved in view of the convergence between S1, S2, and S3 spinal levels (see effects of posterior tibial nerve stimulation on overactive bladder or perineal pain).…”