title: Third sacral foramina morphometry for sacral neuromodulation.
abstract: OBJECTIVE
  This study is aimed to define the geometry and location of the human S3 foramen, with respect to bony landmarks visible on ultrasound.
  
  
  METHODS
  Computed tomographic (CT) image data from an institutional review board-approved database of de-identified pelvic CT images were analyzed. Points along the S3 foramina and bony sacrum were tagged, and their locations saved. The saved points were mathematically analyzed to determine the geometry and relative location of the S3 foramina with respect to other bony landmarks, specifically the sacral hiatus, and the sacral spinous processes, and the caudad aspect of the bilateral SI joints ("SI line"). Descriptive statistics were used to describe the geometry and aggregate location of the S3 foramina bilaterally. CT data sets were excluded if they had evidence of pelvic bone injury, prior bony fixation, severe osteoporosis, or other deformity.
  
  
  RESULTS
  One hundred thirty-three data sets met the inclusion criteria. The SI line was superior to the sacral hiatus for reliable S3 localization. The entire circumference of approximately 14% of the S3 foramina is located cephalad to the SI line. The sagittal angle of trajectory for S3 was approximately 70 degrees relative to the dorsal surface of the sacrum.
  
  
  CONCLUSIONS
  Clinical localization of the S3 foramen for sacral neuromodulator needle placement is best obtained when the needle tip is positioned 15 to 25 mm lateral to the sacral spinous processes and 0.0 cm to 25 mm caudad to the SI line, at the level of the dorsal sacrum surface. The findings presented in this study may be applied to improve the efficacy and accuracy of neuromodulator lead placement into the S3 foramen. This study provides rationale for the effectiveness of the crosshair placement technique and demonstrates the best location for needle repositioning when this technique is not initially successful.
authors: University of South Florida, Tampa, FL, USA. mona_mccullough@yahoo.com
authors: Mona C
authors: MC
authors: McCullough
authors: Summer
authors: S
authors: Decker
authors: Jonathan
authors: J
authors: Ford
authors: Katheryne
authors: K
authors: Downes
authors: Don
authors: D
authors: Hilbelink
authors: Raul
authors: R
authors: Ordorica
authors: Lennox
authors: L
authors: Hoyte
authors: Stuart
authors: S
authors: Hart
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004599:Electric Stimulation Therapy; D005242:Fecal Incontinence / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012447:Sacrum / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D014555:Urination Disorders / Q000628:therapy*; D055815:Young Adult