title: Brief review: piriformis syndrome: etiology, diagnosis, and management.
abstract: OBJECTIVE
  In this narrative review, we aim to provide the pathophysiology and diagnostic criteria of the piriformis syndrome (PS), an underdiagnosed cause of buttock and leg pain that can be difficult to treat. Based on existing evidence, frequencies of clinical features are estimated in patients reported to have PS. In view of the increasing popularity of ultrasound for intervention, the ultrasound-guided technique in the treatment of PS is described in detail.
  
  
  METHODS
  A literature search of the MEDLINE® database was performed from January 1980 to December 2012 using the search terms e.g., " piriformis injection", " ultrasound guided piriformis injection", " botulinum toxin", "pain management", and different structures relevant in this review. There was no restriction on language.
  
  
  RESULTS
  A review of the medical literature pertaining to PS revealed that the existence of this entity remains controversial. There is no definitive proof of its existence despite reported series with large numbers of patients.
  
  
  CONCLUSIONS
  Piriformis syndrome continues to be a controversial diagnosis for sciatic pain. Electrophysiological testing and nerve blocks play important roles when the diagnosis is uncertain. Injection of local anesthetics, steroids, and botulinum toxin into the piriformis muscle can serve both diagnostic and therapeutic purposes. An ultrasound-guided injection technique offers improved accuracy in locating the piriformis muscle. Optimizing the therapeutic approach requires an interdisciplinary evaluation of treatment.
authors.affiliation: Regional Pain Management Center DGS, Luxemburger Strasse 323-325, 50354, Cologne-Huerth, Germany, danilo@jankovic1.de.
authors.forename: Danilo
authors.initials: D
authors.lastname: Jankovic
authors.forename: Philip
authors.initials: P
authors.lastname: Peng
authors.forename: André
authors.initials: A
authors.lastname: van Zundert
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage; D001905:Botulinum Toxins / Q000008:administration & dosage; D004568:Electrodiagnosis / Q000379:methods; D005938:Glucocorticoids / Q000008:administration & dosage; D006801:Humans; D009407:Nerve Block / Q000379:methods; D010146:Pain / Q000209:etiology*; D059408:Pain Management / Q000379:methods*; D055958:Piriformis Muscle Syndrome / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D018084:Ultrasonography, Interventional / Q000379:methods
chemical_list: D000779:Anesthetics, Local; D005938:Glucocorticoids; D001905:Botulinum Toxins