MRI Guidance Assists Exstrophy Closure

Bladder exstrophy is a rare birth condition where the abdominal all and pelvis fail to completely fuse, leaving a child with a variety of congenital abnormalities that can include an incompletely formed pelvis, bladder and genitals. Bladder exstrophy affects between one in 10-50,000 children; an even rarer form known as cloacal exstrophy includes an incomplete formation of the intestine and affects one in 400,000 live births.

Drs. John P Gearhart, MD and Heather DiCarlo, MD.

The Johns Hopkins Children's Center is a world leader and referral center for the treatment of exstrophy. Starting with the pioneering work of Robert Jeffs and John P. Gearhart four decades ago, the Johns Hopkins Children's Center now treats hundreds of children each year with the disease. Heather DiCarlo, MD, is one of the newest pediatric urologists to join the team at Johns Hopkins. Dr. DiCarlo is furthering the legacy of Jeffs and Gearhart using MRI-guided navigation to improve our understanding of the pelvic floor anatomy in these children, provide information during the surgical closure and create landmarks to facilitate teaching of the procedure.


The MRI-guided system uses technology typically used by neurosurgeons and orthopedists for complex brain and spinal surgeries. The Federal Drug Administration and Institutional Review Board of Johns Hopkins recently approved the MRI-based system for use in children with exstrophy. The day prior to a planned exstrophy closure, the child undergoes a pelvic MRI. Images from the pelvic MRI are reviewed by Dr. DiCarlo and Aylin Tekes, MD, a pediatric radiologist at Johns Hopkins. Important anatomic structures, including the bony landmarks of the pelvis (the anterior superior iliac spine and pelvic tubercles) and soft tissue landmarks (like the umbilicus and anus), are identified and marked using the MRI-guided technology. The following day in the operating room, DiCarlo is able to "register" (or align) the MRI images with a real-time pointer using a strap that is temporarily placed on the child's chest – where it remains stable during the surgery. Using the pointer, DiCarlo can then correlate the patient's surgical anatomy with the MRI images – allowing her to identify and preserve important structures and observe how changes in the pelvic anatomy during surgery can affect correlated structures on MRI. Dr. Paul Sponseller, MD, a pediatric orthopedic surgeon, can then realign and "fix" the pelvis, correcting the bony abnormalities associated with the disease.

From http://www.medscape.com/viewarticle/583538_3

A secure closure of the bladder and pelvis is the crucial step in the operation and it involves identification, dissection and preservation of the pelvic floor muscles. Dr. DiCarlo explains,

"When we're operating we are able to see those muscles, and we know we're getting those fibers completely dissected."

To date, the MRI-guided system has been used on 10 boys and girls undergoing bladder exstrophy closure or reclosure. All have done well without adverse events and DiCarlo and the multidisciplinary exstrophy team continue to learn from the technology. It is their hope that the MRI-guided system may help in other complex surgeries like the repair of cloacal exstrophy or epispadias.

 
The story was extracted from "A Novel Approach to Bladder Exstrophy Closure Yields Insights" in Johns Hopkins Urology: News for Physicians, Winter 2015 by Johns Hopkins Medicine.