The clinical features of the piriformis syndrome

Abstract

In their otherwise comprehensive review of the piriformis syndrome, Cassidy and colleagues [1] overlooked two systematic reviews on the subject. Hopayian et al. [3] have reviewed the diagnostic features and Cramp et al. [2] have reviewed conservative management.Evidence on the symptoms and signs of the syndrome are to be found in case reports and case series. Because such data are frequently taken from routine records where significant negative findings may not be recorded, calculating the frequency of clinical features requires a specific type of analysis. A range of frequencies, from all cases reported to only those that specifically reported both positive and negative findings, must be provided. The review by Hopayian et al. [3] synthesised the information dispersed across over 50 case studies. The reviewers identified the three commonest symptoms as buttock pain (range 50-95 %), pain aggravated by sitting (39-97 %) and external tenderness near the greater sciatic notch (59-92 %). There were insufficient numbers to calculate a frequency for the FAIR test, which Cassidy et al. focussed on. However, other signs of sciatic nerve impingement were present in 32-74 %.Cramp et al. [2] found few good quality studies of the effectiveness of non-surgical treatments but there was limited evidence for the effectiveness of botulinum toxin injection. We are unlikely to get high quality research on the treatment of piriformis syndrome until we have defined the syndrome more rigorously. The best way forward is a prospective study of clinical features matched to imaging. I believe that a good starting point is with the clinical features identified through systematic reviews.