High Frequency Ultrasonography

Piriformis syndrome ( PS ) is rare, presenting with symptoms and signs closely resembling L5 and S1 radiculopathy. It is a diagnosis of exclusion, requiring a high index of suspicion. Numerous clinical tests and electrodiagnosis are inconclusive. Magnetic Resonance Neurography (MRN) of Sciatic nerve yields better results but is limited by cost and lack of availability at all centres. High frequency ultrasonography (HFUS) of the Sciatic nerve overcomes the above limitations and is a reliable tool for positive diagnosis with ease of performance especially in various dynamic postures. Conventional treatment of PS is unrewarding to the physician and frustrating to the patient whereas Botulinum toxin injection into the Piriformis muscle under ultrasound guidance gives considerable relief from pain. A pilot series of five patients with clinical features of PS, confirmed by diagnostic HFUS, three of whom were injected with a fixed dose of Botulinum Toxin type A (50 units) into the Piriformis muscle on the affected side are described. Pain assessment before and three weeks after injection using the Numeric Rating Scale (NRS) demonstrated significant improvement