Piriformis muscle syndrome: A diagnostic dilemma

Objective: To evaluate the role of modified H reflexes in confirming a diagnosis of piriformis muscle syndrome. Methods: Six consecutive patients who met stringent inclusion criteria establishing the presence of this disorder underwent electrodiagnostic testing including the completion of modified H reflexes as described by Fishman. Results: A positive predictive value of 33% was obtained. Conclusions: This study does not support the role of electrodiagnostic testing with modified H reflexes in the evaluation of a patient with possible piriformis muscle syndrome. An algorithmic approach for the diagnosis of piriformis syndrome which incorporates examination findings, injection techniques, and visual anatomic studies, is offered.