Poster 91: Tumor infiltration of the piriformis muscle resulting in piriformis syndrome: a case report

Abstract

Setting: Tertiary care hospital. Patient: A 53-year-old female with high-grade, non-Hodgkin’s lymphoma. Case Description: The patient was admitted to the rehabilitation unit after a complicated hospital course. She complained of persistent right buttock pain associated with pain and numbness radiating down her right posterolateral leg to her lateral foot. She did not complain of low back pain, left lower-extremity symptoms, or bowel or bladder dysfunction. Her pain was accentuated with adduction, internal rotation, and flexion of her right lower limb. She demonstrated tenderness, increased pain, and worsening of symptoms with palpation over the right piriformis muscle. Neurologic exam revealed intact strength with normal tone, however, light touch was abnormal in the right L5-S1 dermatomes. Magnetic resonance imaging revealed an extensive pelvic tumor involving the cervix and adnexal regions extending to the margins of the right piriformis muscle. Assessment/Results: Tumor infiltration throughout the pelvis involving the right piriformis muscle likely resulted in right buttock and lower-extremity pain and parathesias. Discussion: A literature search revealed no other cases of tumor infiltration causing piriformis syndrome. The most common etiology of piriformis syndrome is local trauma resulting in muscle spasm, inflammation, and hypertrophy. As a result, the sciatic nerve is compressed either between the piriformis muscle belly and the bony pelvis or between 2 inflamed fascicles. In this case report, it is probable that compression of the sciatic nerve resulted from direct compression by the tumor or as a result of secondary inflammation within the muscle belly. Furthermore, the tumor infiltration may have caused irritation of the piriformis resulting in muscle spasms and thus compression of the sciatic nerve as it pierced the muscle. Conclusion: Tumor infiltration of the piriformis muscle is a rare cause of piriformis syndrome.