The piriformis syndrome-aspecial indication for botulinum toxin

Abstract

The piriformis syndrome (PiS) is apossible cause of gluteal pain radiating into the legs. From apathophysiological anatomical point of view adivision into primary and secondary PiS is made. A primary PiS is based on variants of the course of the sciatic nerve with respect to the piriformis muscle. Asecondary PiS occurs as aresult of hypertrophy, tension and hardening of the piriformis muscle. Muscular hypertrophy causes an impingement syndrome with pressure on the sciatic nerve in the infrapiriform foramen more often than course variants. Atentative diagnosis of PiS can be made based on anamnestic information, clinical signs of strain and the flexion adduction internal rotation (FAIR) test. If asymmetry or hypertrophy exists, the tentative diagnosis is substantiated with the representation of the piriformis muscle in computed tomography (CT). Thus, aCT-supported botulinum injection (BTX) into the piriformis muscle is indicated. This is apathogenetic treatment approach leading to areduction in volume. In most cases asingle treatment is sufficient. Since there are no adverse consequences, the BTX into the piriformis muscle is also justified from adiagnostic and therapeutic point of view in cases of primary PiS if the clinical indications are clear and other causes can be ruled out. In an in-house case series the tentative diagnosis of PiS could be made for 19patients and the effectiveness of BTX was confirmed.