Restoring Bladder Function Using Motor and Sensory Nerve Transfers: A Cadaveric Feasibility Study
Benjamin R Johnston, MD, PhD1, Brian McIntyre, BS2, Michael R Ruggieri, PhD3, Mary F Barbe, PhD3 and Justin Brown, MD4, (1)Alpert Medical School, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, (2)Drexel University - Medicine, Philadelphia, PA, (3)Temple University, Philadelphia, PA, (4)Massachusetts General Hospital, Boston, MA
Micturition is controlled by a neural circuit involving the brain, spinal cord, mesenteric ganglia, and pelvic plexus that coordinate urine storage and voiding. Neurogenic bladder dysfunction, characterized by retention, incontinence, and detrusor spasticity results when this circuit is injured. Management of bladder dysfunction includes: clean intermittent self-catheterization, sacral nerve stimulation, urinary diversion by conduit to the bowel, pharmacotherapy, or use of an indwelling suprapubic or urethral catheter. In a review of the health priorities of spinal cord injury patients, Simpson et al., 2012, found the top priority was restoration of bowel and bladder function, followed by restoration of upper extremity motor function, and then sexual function. We propose a series of three nerve transfers that would allow for functional restoration of detrusor and external urethral sphincter function, along with sensory reinnervation of the pudendal nerve. The first transfer of the posterior branch of the obturator nerve to the pelvic nerve provides a feasible mechanism for patients to initiate detrusor contraction by thigh adduction. Second, external urethra innervation will be accomplished by transfer of the vastus medialis nerve to the pudendal nerve. Finally, the sensory component of the pudendal nerve to the genitalia may be restored by transfer of the saphenous nerve. The main limitations for connecting the nerves in the anterior compartments of the thigh to their pelvic targets are the bifurcation or arborization points of their parent nerve. To ensure a transfer, we sought to measure these distances in cadavers. Methods: 26 pelvic and anterior thigh regions were dissected in 13 female cadavers. After the graft and donor sites were clearly exposed and branches identified, the donor nerves were cut at suitable distal sites and then moved to the pelvis for a tensionless anastomosis. Results: the obturator nerve bifurcated 5.5 cm from the pelvic wall (SD 1.7 cm, range 2.0-9.0 cm). In every cadaver we were able to bring the posterior division of the obturator to the vesicular branch of the pelvic nerve (ischial spine) in a tensionless manner with an excess obturator of 2.0 cm (SD 1.2 cm, range 0.0-5.0 cm). ASIS to femoral nerve arborization was 9.3 cm (SD 1.8 cm, range 6.5-15.0 cm) and the arborization to ischial spine was 12.9 cm (SD 1.4 cm, range 10.0-16.0 cm). Discussion: our proposed nerve transfers allow for reinnervation of more components of the micturition pathway and directly address the quality of life issues that patients most frequently report.
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