Anatomical Proximity Between Sciatic Nerve and Ischial Spine and its Relationship to the Development of Deep Gluteal Pain Syndrome.

OBJECTIVE: Deep gluteal syndrome (DGS) is a medical diagnosis in which the pathoanatomy of the subgluteal space contributes to pain. The growing recognition that gluteal neuropathies can be associated with the presence of a bone-neural conflict with irritation or compression may allow us to shed some light on this pathology. This study aims to determine whether the location of the sciatic nerve (SN) in relation to the ischial spine (IS) contributes to the development of DGS. METHODS: The SN - IS relationship was analyzed based on magnetic resonance imaging (MRI) in 15 surgical patients (SPs), who underwent piriformis release, and in 30 control patients who underwent MRI of the pelvis for reasons unrelated to sciatica. The SN exit from the greater sciatic foramen was classified as either zone A (medial to the IS); zone B (on the IS); or zone C (lateral to the IS). RESULTS: The SN was significantly closer to the IS in SPs than in MRI controls (P = 0.014). When analyzing patients of similar age, SNs in SPs were significantly closer (P = 0.0061) to the IS, and located in zone B significantly more (P = 0.0216) as compared to MRI controls. Patients who underwent surgery for piriformis release showed a significant decrease in pain postoperatively (P < 0.0001). CONCLUSIONS: The results from this study suggest that the relationship between the IS and SN may play a role in the development of DGS. This may also help establish which patients would benefit more from surgical intervention.

Anatomical Relationships of the Sciatic Nerve and Pudendal Nerve to the Ischial Spine as They Exit the Greater Sciatic Foramen.

OBJECTIVE: Deep gluteal syndrome is a clinical condition in which discomfort may arise due to the pathoanatomy of the subgluteal space. We conducted an anatomical exploration to categorize the relationship of the piriformis muscle, sciatic nerve (SN), and pudendal nerve (PN) to the ischial spine (IS) and sacrospinous ligament. METHODS: We analyzed 22 cadavers. The piriformis muscle, SN, and PN were exposed through either a transgluteal approach or a gluteal flap. The relationship of the neural structures to the IS, sacrospinous ligament, and ischial bone as they exit the greater sciatic foramen was observed, and the exit zones were classified as zone A, medial to the IS (entirely on sacrospinous ligament); zone B, on the IS; and zone C, lateral to the IS (entirely on ischial bone). RESULTS: The SN was observed either in zone B or zone C in all specimens. The PN was found to be in either zone A or zone B in 97.6% of specimens. The most common combinations were SN in zone B and PN in zone A (type I), and SN in zone C and PN in zone B (type II). CONCLUSIONS: The results from this study show clear anatomical differences in the SN-PN relationship, which may play a role in pain seen in deep gluteal syndrome. Moreover, classification of the SN-IS and PN-IS relationships described in this article will help describe different pathologies affecting the deep gluteal area.