Piriformis Syndrome as a Cause of Non-discogenic Sciatic Pain in a Young Bharatanatyam Dancer

Dear Editor, A 19-year-old dancer with no prior comorbidities presented to us with acute-onset pain radiating from the right gluteal region to the dorsum of the toes involving the posterior thigh and posterior leg. This was associated with tingling paresthesias in the same region. She reported that the pain was exacerbated in a sitting position. She was a trained Kathak dancer for 10 years and had been engaging in intense Bharatanatyam dance practice for 4 hours/day for the last 2 months. However, on examination, there were no sensory or motor deficits. Reflexes were normal. The straight leg raising test and flexion, adduction, and internal rotation (FAIR) test were negative. Based on her history, a possibility of L5 radiculopathy was considered as the pain was radiating down the right leg to the big toe. A differential diagnosis of sciatic neuropathy and piriformis syndrome (PS) was also considered. The exacerbation of pain in the sitting position pointed to the possibility of PS, though the FAIR test was negative. Magnetic resonance imaging (MRI) of the spine was normal [Figure 1a]. MRI of the pelvis was asked for to rule out a plexus/sciatic nerve lesion, and it revealed a bulky right piriformis muscle measuring 22 mm compared to the left (13 mm) [Figure 1b]. There was also abnormal short tau inversion recovery (STIR) hyperintensity involving the right femoral greater trochanter and head, suggestive of stress edema secondary to piriformis traction [Figure 1c]. A routine nerve conduction study was performed, which was normal. A final diagnosis of right PS was made.Figure 1: MRI of the spine and pelvis. (a) Sagittal section of MRI of the whole spine was normal. (b) Axial section of pelvic muscles revealed hypertrophied right piriformis muscle (22 mm, thick arrow) compared to the left (11 mm, thin arrow). (c) Coronal STIR of the pelvis revealed hyperintensity involving right greater trochanter and head of femur, suggestive of stress edema (arrow). MRI = magnetic resonance imaging, STIR = short tau inversion recoveryPS is a disorder of sciatic nerve entrapment at the level of ischial tuberosity.[1] Prevalence has been reported to be 17.2% in patients with low back pain.[2] PS is characterized by shooting, burning, or aching pain in the gluteal region radiating down to the back of the leg, aggravated on sitting, and pain on maneuvers increasing piriformis muscle tension like FAIR test and Lasègue sign.[1,2] Professional weight lifters and those involved in occupations requiring prolonged sitting (taxi drivers, bicycle riders, or office workers) are prone to develop PS.[1] However, dancing as a cause of PS is underreported.[3-5] Dancers may be at higher risk for PS based on postures and steps they perform. Piriformis is a flat muscle that is pyramidal in shape; it originates from the anterior aspect of the sacrum and the greater sciatic notch and inserts to the apex of the greater trochanter of the femur. Piriformis is primarily responsible for the external rotation of the hip assisted by the quadratus femoris, obturator internus, and gemellus muscles. External rotation of the hip is essential for achieving the turned-out position (feet turned out 180° to each other), a fundamental posture in Bharatanatyam and other classical dance forms.[3] In addition, the piriformis is involved in weak abduction and flexion of the hip, as well as stabilization of the pelvic girdle, and remains constantly engaged during dancing.[4] Injury to the piriformis muscle can occur from a single traumatic incident involving twisting of the leg with the foot firmly planted or from repetitive microtrauma due to overuse.[3] Kathak, a North Indian classical dance form, involves fast-paced movements with intricate footwork, hand gestures, and spins.[6] It involves straight tapping of feet.[6] In contrast, Bharatanatyam, a South Indian classical dance form, features a wide range of poses, intricate footwork, and hand gestures. It includes two main postures: Araimandi, a half squat with heels joined and knees and feet pointing in opposite directions, and Muzhumandi, a full squat involving sitting on toes with knees bent, heels joined, and hands behind the waist.[6,7] These movements demand precise abduction, internal/external hip rotation, and flexion/extension at the knee, often sustained for prolonged durations, placing significant stress on pelvic muscles. Our patient experienced no pain during Kathak practice but developed PS during Bharatanatyam, which may be due to the new postures adopted and the intense training of Bharatanatyam. Dancers may be prone to injuries in either leg, but the specific risk can vary depending on factors such as individual technique, choreography, and frequency of practice. While both legs are utilized extensively in Bharatanatyam, certain movements or repetitive patterns may place greater stress on one leg over the other, potentially increasing the risk of injury to that side. Studies have also shown that Bharatanatyam dancers are more prone to developing injuries in the right lower limb than in the left lower limb.[6] In our patient also, the right piriformis was involved along with stress edema of the right greater trochanter and head of the femur. Diagnosis of PS is done by history and examination, followed by documentation of enlarged piriformis muscle in computed tomography or MRI of the pelvis. The FAIR test has been reported to be 88% sensitive and 83% specific.[8] Our patient had sciatica, but the FAIR test was negative. However, imaging revealed enlarged piriformis muscle and stress edema in the greater trochanter and head of the femur, leading to a diagnosis of PS. Treatment consists of conservative management with rest, analgesics, and muscle relaxants. For refractory cases, local steroid or botulinum toxin injection can be tried.[9] Piriformis tenotomy and decompression of sciatic nerve can be done for nonresponders.[10] Our patient improved with rest and analgesics. This case highlights the importance of looking for PS in dancers presenting with gluteal pain and/or sciatica pain, especially those practicing Bharatanatyam. Declaration of patient consent The authors certify that due informed consent was taken from the patient as per the guidelines of the Institutional Review Board for writing and publishing the clinical details and radiological images. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.