Lina Chen MD, Presenter: Nothing to Disclose

Richard P. Marvel MD, Abstract Co-Author: Nothing to Disclose

Howard Marks Richard MD, Abstract Co-Author: Nothing to Disclose

The pudendal nerve is a predominately sensory nerve arising from s2-4 nerve roots. Several potential sites of entrapment lie along the course of the nerve. One critical zone of compression is adjacent to the ischial spine and sacrotuberous ligament.  We hypothesize that variations in bony anatomy of the ischial spine may predispose patients to pudendal nerve compression. The goal of this study was to use 3D computed tomography (CT) to identify reliable measurement of ischial spine orientation and to determine if such metrics can differentiate patients with pudendal neuralgia from control patients without neurological symptoms.

In this IRB-approved study, CT of the bony pelvis in 32 women were retrospectively reviewed, including 16 patients (ages 22-78 y; mean = 54.3+/-15 y) diagnosed with pudendal nerve compression syndrome and who underwent pudendal nerve block; 16 patients (ages 22-94 y; mean 64+/-19 y) who presented with trauma but had no documented neurologic symptoms.  Exclusion criteria include diffuse pelvic pathology, such as Paget disease and metabolic bone disease, pelvic fracture, extensive calcification or ossification of soft tissue, and presence of hardware. Using the TeraRecon 3D CT application, an axial oblique CT image at the level of the tip of the bilateral ischial spine and mid symphysis pubis was obtained. Six methods of measurements were performed by a musculoskeletal radiologist with 5 y subspecialty experience. Each measurement was performed twice, separated by at least 1 month. The Student t test was used to compare differences in measurements between the two groups.

Of the CT measurements, the difference in the angle between the ischial spine and inner pelvic wall was found to be statistically significant between the control and neuralgia patients.  Right side: neuralgia 126+/-4.8 degrees, control 135+/-4.9, P = 0.015; left side: neuralgia 126+/-2.4, control 134+/-5.4, P = 0.044). Intra-observer correlation coefficient was 0.80.

Assessment of the orientation of ischial spine using 3D CT may help identify patients at risk of developing pudendal compression neuropathy.

This study demonstrates potential application of clinical 3D CT in identify patients at risk of developing pudendal compression neuropathy.

Chen, L, Marvel, R, Richard, H, Analysis of Ischial Spine Orientation in Patients with Compression-mediated Pudendal Neuropathy: A Study Using 3D Computed Tomography.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13011325.html