Mo1998 Magnetic Resonance Diffuse Tensor Imaging Based Muscle Fiber Tracking Confirms the “Purse String” Nature of the External Anal Sphincter

The external anal sphincter (EAS) may be injured in 25–35% of women during the first and subsequent vaginal childbirths and is likely the most common cause of anal incontinence. Since its first description almost 300 years ago, the EAS was believed to be a circular or a “donut-shaped” structure. Using three-dimensional transperineal ultrasound imaging, MRI, diffusion tensor imaging, and muscle fiber tracking, we delineated various components of the EAS and their muscle fiber directions. These novel imaging techniques suggest “purse-string” morphology, with “EAS muscles” crossing contralaterally in the perineal body to the contralateral transverse perineal (TP) and bulbospongiosus (BS) muscles, thus attaching the EAS to the pubic rami. Spin-tag MRI demonstrated purse-string action of the EAS muscle. Electromyography of TP/BS and EAS muscles revealed their simultaneous contraction and relaxation. Lidocaine injection into the TP/BS muscle significantly reduced anal canal pressure. These studies support purse-string morphology of the EAS to constrict/close the anal canal opening. Our findings have implications for the effect of episiotomy on anal closure function and the currently used surgical technique (overlapping sphincteroplasty) for EAS reconstructive surgery to treat anal incontinence.

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Sa1350 Magnetic Resonance Diffusion Tensor Imaging & Muscle Fiber Tractography Show Defects of the Transverse Perinea and Bulbospongiosus Muscles of the External Anal Sphincter Complex in Patient With Anal Incontinence

Gastroenterology ◽

10.1016/s0016-5085(15)30990-2 ◽

2015 ◽

Vol 148 (4) ◽

pp. S-299

Author(s):

Ravinder K. Mittal ◽

Melissa M. Ledgerwood ◽

Shantanu Sinha

Keyword(s):

Diffusion Tensor Imaging ◽

Magnetic Resonance ◽

Anal Sphincter ◽

Muscle Fiber ◽

Anal Incontinence ◽

External Anal Sphincter ◽

Diffusion Tensor ◽

Fiber Tractography ◽

Sphincter Complex ◽

Anal Sphincter Complex

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Preoperative Assessment of External Anal Sphincter Invasion and Para-external Anal Sphincter Invasion in Rectal Cancer Using Magnetic Resonance Imaging

Nippon Daicho Komonbyo Gakkai Zasshi ◽

10.3862/jcoloproctology.59.367 ◽

2006 ◽

Vol 59 (7) ◽

pp. 367-372

Author(s):

M. Ishii ◽

S. Yuen ◽

S. Yamaguchi ◽

H. Morita ◽

S. Saito ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Rectal Cancer ◽

Magnetic Resonance ◽

Anal Sphincter ◽

External Anal Sphincter ◽

Preoperative Assessment ◽

Resonance Imaging

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Endo-anal ultrasound versus endo-anal magnetic resonance imaging for the depiction of external anal sphincter pathology in patients with faecal incontinence: a systematic review

Magyar Sebészet (Hungarian Journal of Surgery) ◽

10.1556/maseb.63.2010.1.2 ◽

2010 ◽

Vol 63 (1) ◽

pp. 9-15 ◽

Cited By ~ 8

Author(s):

MS Sajid ◽

K Khatri ◽

MRS Siddiqui ◽

MK Baig

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Anal Sphincter ◽

Faecal Incontinence ◽

External Anal Sphincter ◽

Fixed Effect Model ◽

Fixed Effect ◽

Resonance Imaging ◽

Anal Ultrasound ◽

Effect Model

Abstract Objective: To evaluate the endo-anal ultrasound (EAUS) versus endo-anal magnetic resonance imaging (EAMRI) in the diagnosis of external anal sphincter defects (EAS) in patients with faecal incontinence (FI). Methods: Studies on EAUS and EAMRI were selected and analyzed to generate summative data. Results: Five studies encompassing 347 patients of FI were included in this review. Three studies validated the results of EAUS and EAMRI by surgery (61 patients). In the fixed effect model, EAUS was superior to EAMRI in the depiction of EAS defects. On combined analysis of five studies using fixed effect model, both EAUS and EAMRI were equally effective. However, there was a significant heterogeneity between studies. Conclusion: EAUS and EAMRI are comparable in the diagnosis of EAS defects in patients of FI. Since EAUS is an economical, quicker and easily available imaging modality, it may be used a preferable investigation for the diagnosis of EAS defects in patients of FI.

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