Deep gluteal syndrome (DGS) is an underdiagnosed entity characterized by pain and/or dysesthesias in the buttock area, hip or posterior thigh and/or radicular pain due to a non-discogenic sciatic nerve entrapment in the subgluteal space. Multiple pathologies have been incorporated in this all-included “piriformis syndrome,” a term that has nothing to do with the presence of fibrous bands, obturator internus/gemellus syndrome, quadratus femoris/ischiofemoral pathology, hamstring conditions, gluteal disorders and orthopedic causes. The concept of fibrous bands playing a role in causing symptoms related to sciatic nerve mobility and entrapment represents a radical change in the current diagnosis of and therapeutic approach to DGS. The development of periarticular hip endoscopy has led to an understanding of the pathophysiological mechanisms underlying piriformis syndrome, which has supported its further classification. A broad spectrum of known pathologies may be located nonspecifically in the subgluteal space and can therefore also trigger DGS. These can be classified as traumatic, iatrogenic, inflammatory/infectious, vascular, gynecologic and tumors/pseudo-tumors. Because of the ever-increasing use of advanced magnetic resonance neurography (MRN) techniques and the excellent outcomes of the new endoscopic treatment, radiologists must be aware of the anatomy and pathologic conditions of this space. MR imaging is the diagnostic procedure of choice for assessing DGS and may substantially influence the management of these patients. The infiltration test not only has a high diagnostic but also a therapeutic value. This article describes the subgluteal space anatomy, reviews known and new etiologies of DGS, and assesses the role of the radiologist in the diagnosis, treatment and postoperative evaluation of sciatic nerve entrapments, with emphasis on MR imaging and endoscopic correlation.
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The authors are grateful to Dr. Suzanne Anderson for her contribution to the revision of the translation of this article.
Conflict of interest
The authors declare they do not have any conflict of interest.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Normal excursion of the sciatic nerve. The video shows the sciatic nerve proximal excursion of 28.0 mm medially, toward the hip joint during hip flexion, adduction and internal rotation and leg raise with knee extension. (MP4 5618 kb)
Fibrovascular band. The video shows the endoscopic resection of a fibrovascular band containing a macroscopically identifiable artery. Care must be taken during this procedure because of the high risk of bleeding. (MP4 14409 kb)
Compressive or bridge-type band. The video shows a type 1B fibrous band, which limits the movement of the sciatic nerve compressing it from posterior to anterior. This fibrous band extends from the posterior border of the greater trochanter to the gluteus maximus and extends up to the greater sciatic notch. (MP4 9936 kb)
Sciatic nerve entrapment secondary to fibrosis after open surgery of piriformis syndrome. The video shows bands anchored to the sciatic nerve in multiple directions with undefined distribution (type-3 bands) that prevent its proper mobility. (MP4 7527 kb)
Sciatic nerve/obturator internus complex variation. The video shows an obturator internus penetrating the sciatic nerve and the subsequent endoscopic resection by radiofrequency of its tendon. (MP4 5978 kb)
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Hernando, M.F., Cerezal, L., Pérez-Carro, L. et al. Deep gluteal syndrome: anatomy, imaging, and management of sciatic nerve entrapments in the subgluteal space. Skeletal Radiol 44, 919–934 (2015). https://doi.org/10.1007/s00256-015-2124-6
- Deep gluteal syndrome
- MR neurography
- Sciatic nerve
- Sciatic neuritis
- Piriformis syndrome
- Posterior hip pain
- External rotators
- Injection test