Piriformis syndrome

Background

• "Sciatica" entrapment not originating from nerve root compression
• Probable compression of sciatic nerve, by piriformis muscle
• Piriformis normally helps ext rotate hip
• Inactive gluteals vs tight hip flexors (so piriformis strains at hip extension & rotation → compressing the sciatic N.)

Clinical

• Clinical diagnosis
• Unilateral (rarely bilat.) buttock pain radiating to hamstrings or below
• F:M = 3:1
• 30 - 40 yo
• Exacerbated by sitting or prolonged "flexion" exercise (e.g. cycling)
• Associated pudendal nerve compression may result in transient saddle paraesthesia or sphincter symptoms
• Symptoms relieved by hip extension or ext. rotation (patients walk "toe out")
• No red flags
• No convincing root irritation (e.g. valsalva) symptoms
• Nil constitutional
• SLR near normal
• No motor, sphincter or perianal pinprick sensation abnormalities
• Trigger point at sciatic notch (½ way between ischium & Gr. trochanter)
• FAIR (hip flexion/adduction/int. rotation) manoeuvre triggers symptoms

Differential Dx

• Cauda equine (BEWARE bilateral, sphincter or motor signs)
• Inflammatory /malignant / cord compression (beware nocturnal / constitutional / red flag symptoms)
• Spinal stenosis
• Cord claudication

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