A Case Report of Deep Gluteal Syndrome Secondary to Piriformis Enthesopathy Successfully Treated With Ultrasound-Guided Dextrose Prolotherapy.

Deep gluteal syndrome (DGS) is a challenging cause of buttock pain and sciatic-like symptoms, often mimicking lumbar radiculopathy and remaining difficult to diagnose when conventional imaging is inconclusive. Structural abnormalities within the deep gluteal space, particularly at muscle-tendon insertions, may contribute to mechanically mediated sciatic nerve irritation but are frequently overlooked. We report a case of DGS in a 45-year-old man, caused by piriformis enthesopathy with a cortically based bony spur at the greater trochanter, identified using computed tomography (CT) and functionally assessed with dynamic ultrasonography. CT allowed precise detection of the bony abnormality, while dynamic USG demonstrated reproducible motion-related changes at the piriformis enthesis during hip rotation, which may provide further information to a patient with DGS. Targeted ultrasound-guided dextrose prolotherapy using a hyperosmolar dextrose solution was performed at the enthesopathic site (six sessions at two-week intervals), resulting in substantial and sustained symptom improvement at three-month follow-up. This case showed that the abnormal MRI findings may not be the cause of the patient's condition, and it highlights the diagnostic value of a multimodal imaging approach combining CT and dynamic ultrasound in this patient. Furthermore, it suggests that ultrasound-guided dextrose prolotherapy could be an effective, minimally invasive treatment option for selected patients with chronic, function-limiting DGS with symptomatic enthesopathy.