Piriformis syndrome refers to a rare, usually clinically diagnosed condition in which the Piriformis muscle compresses or irritates the Sciatic nerve. From a neurosurgical perspective, it is an extraspinal compression syndrome of the sciatic nerve and therefore an important differential diagnosis in patients with radicular leg symptoms without corresponding findings in the lumbar spine.
Epidemiology
Estimates suggest that approximately 0.3–6 % of all patients with “sciatica symptoms” have piriformis syndrome. Sport-active individuals and patients with anatomical variants of the sciatic nerve (e.g., passage through the piriformis muscle) are affected more frequently.
Etiology
Common causes of piriformis syndrome include:
Hypertrophy or tension of the piriformis muscle, for example due to overuse, trauma, or abnormal loading.
Posttraumatic changes after a fall or direct trauma to the buttocks
Anatomical variants (e.g., divided sciatic nerve fascicles)
Diagnosis
This is primarily a clinical diagnosis of exclusion. The following clinical tests may be helpful in the diagnosis of piriformis syndrome:
FAIR test (flexion, adduction, internal rotation)
Freiberg maneuver
Pace test
Beatty maneuver
Treatment
The gold standard in the treatment of piriformis syndrome is conservative therapy consisting of:
Stretching and strengthening exercises as part of physical therapy
Pharmacological pain management, for example with NSAIDs
CT- or ultrasound-guided injection of the piriformis muscle[^1]
Prognosis
The prognosis is good when the diagnosis is correct. The majority of patients achieve significant symptom relief with conservative therapy.