Restoring bladder function using motor and sensory nerve transfers: a cadaveric feasibility study

Abstract

Objective: Bladder dysfunction after nerve injury has a variable presentation, and extent of injury determines whether the bladder is spastic or atonic. The authors have proposed a series of 3 nerve transfers for functional innervation of the detrusor muscle and external urethral sphincter, along with sensory innervation to the genital dermatome. These transfers are applicable to only cases with low spinal segment injuries (sacral nerve root function is lost) and largely preserved lumbar function. Transfer of the posterior branch of the obturator nerve to the vesical branch of the pelvic nerve provides a feasible mechanism for patients to initiate detrusor contraction by thigh adduction. External urethra innervation (motor and sensory) may be accomplished by transfer of the vastus medialis nerve to the pudendal nerve. The sensory component of the pudendal nerve to the genitalia may be further enhanced by transfer of the saphenous nerve (sensory) to the pudendal nerve. The main limitations of coapting the nerve donors to their intrapelvic targets are the bifurcation or arborization points of the parent nerve. To ensure that the donor nerves had sufficient length and diameter, the authors sought to measure these parameters.

Methods: Twenty-six pelvic and anterior thigh regions were dissected in 13 female cadavers. After the graft and donor sites were clearly exposed and the branches identified, the donor nerves were cut at suitable distal sites and then moved into the pelvis for tensionless anastomosis. Diameters were measured with calipers.

Results: The obturator nerve was bifurcated a mean ± SD (range) of 5.5 ± 1.7 (2.0-9.0) cm proximal to the entrance of the obturator foramen. In every cadaver, the authors were able to bring the posterior division of the obturator nerve to the vesical branch of the pelvic nerve (located internal to the ischial spine) in a tensionless manner with an excess obturator nerve length of 2.0 ± 1.2 (0.0-5.0) cm. The distance between the femoral nerve arborization and the anterior superior iliac spine was 9.3 ± 1.8 (6.5-15.0) cm, and the distance from the femoral arborization to the ischial spine was 12.9 ± 1.4 (10.0-16.0) cm. Diameters were similar between donor and recipient nerves.

Conclusions: The chosen donor nerves were long enough and of sufficient caliber for the proposed nerve transfers and tensionless anastomosis.

Keywords: bladder; detrusor muscle; incontinence; micturition; obturator nerve; sacral.

FIG. 1.

Nerve transfer options—both donors and targets—for bladder reinnervation. Figure is available in color online only.

FIG. 2.

A: Illustration of the intrapelvic nerves of interest. The left field of view shows the obturator nerve (dashed red line) and the vesical branch of the pelvic nerve (the red line indicates the axotomy point) in their original positions. The right field of view shows neurolysis of the obturator divisions and reflection for coaptation with the vesical branch (red arrow). B: Intrapelvic dissection of the obturator nerve (pubic symphysis is indicated by the blue arrow). C: Careful splitting of the obturator at the obturator foramen (blue arrow). D: Proximal extension and transection of the posterior division. E: Aligning the posterior division of the obturator nerve adjacent to the ureter bundle with the vesical branch of the pelvic nerve (red vessel loop). F: Size comparison of the obturator nerve (in forceps) with the vesical branch of pelvic nerve (red vessel loop). © Margaret Sten, published with permission.

FIG. 3.

A: Illustration of the donor nerves and landmarks. The dashed lines indicate the measured distances for preoperative planning (ASIS and the greater trochanter of the femur to the femoral nerve arborization) and the distance from the femoral nerve arborization to the intrapelvic coaptation site. B: Key branches of the femoral nerve are color highlighted to correspond with the labeled nerves in panel A. The black dashed line indicates the inguinal ligament. n. = nerve. © Margaret Sten, published with permission.