Piriformis muscle syndrome: diagnostic criteria and treatment of a monocentric series of 250 patients.

OBJECTIVES

Piriformis Muscle Syndrome (PMS) is caused by sciatic nerve compression in the infrapiriformis canal. However, the pathology is poorly understood and difficult to diagnose. This study aimed to devise a clinical assessment score for PMS diagnosis and to develop a treatment strategy.

MATERIAL AND METHODS

Two hundred and fifty patients versus 30 control patients with disco-radicular conflict, plus 30 healthy control subjects were enrolled. A range of tests was used to produce a diagnostic score for PMS and an optimum treatment strategy was proposed.

RESULTS

A 12-point clinical scoring system was devised and a diagnosis of PMS was considered 'probable' when greater or equal to 8. Sensitivity and specificity of the score were 96.4% and 100%, respectively, while the positive predictive value was 100% and negative predictive value was 86.9%. Combined medication and rehabilitation treatments had a cure rate of 51.2%. Hundred and twenty-two patients (48.8%) were unresponsive to treatment and received OnabotulinumtoxinA. Visual Analogue Scale (VAS) results were 'Very good/Good' in 77%, 'Average' in 7.4% and 'Poor' in 15.6%. Fifteen of 19 patients unresponsive to treatment underwent surgery with 'Very good/Good' results in 12 cases.

CONCLUSIONS

The proposed evaluation score may facilitate PMS diagnosis and treatment standardisation. Rehabilitation has a major role associated in half of the cases with botulinum toxin injections.