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.

Anatomical Location of the Vesical Branches of the Inferior Hypogastric Plexus in Human Cadavers

“…We have had success in a number of pre-clinical canine studies in restoring bladder function by transferring a somatic peripheral nerve (donor choices have included obturator, femoral, sciatic, and genitofemoral nerve branches) to vesical nerves of the IHP located adjacent to or on the bladder wall [21][22][23], which are at the distal ends of the anterior division of the inferior hypogastric plexus (IHP). We have previously demonstrated in several human cadaveric studies that somatic nerve transfer to vesical branches of the IHP is technically feasible using ilioinguinal, femoral, and obturator nerve branches [12,13,24]. However, further clarification of the location, size, and relationships of the vesical branches of the IHP and pelvic ganglion is warranted to assist with their identification during surgical procedures.…”

“…Although the diameter of many lower extremity nerves has been defined through many prior studies, the vesical branches of the IHP have not been equally studied in humans. We previously reported that the mean diameter of vesical branches of the IHP was 2.1 mm when measured using a caliper during anatomical dissections [24] in which the nerve branches were still covered with perineurium, fat, and other fascia. However, histological assessment of the nerves after sectioning (which allows for the distinguishment of nerve versus surrounding connective tissues and fat) revealed smaller actual nerve diameters of 0.32 to just over 1 mm (with a mean of 0.53 ± 0.05 mm).…”

“…Because of this pre-clinical success, we continue to pursue clinical translation to patients with flaccid bladders after sacral injuries or sacral chordoma removal (which injures/removes sacral motor roots and/or nerves innervating the bladder). We have previously demonstrated in several human cadaveric studies that somatic nerve transfer to vesical branches of the IHP is technically feasible using ilioinguinal, femoral, and obturator nerve branches [12,13,24]. Another group has transferred the obturator nerve to the pelvic splanchnic nerve for recovery of urination function after sacral plexus injury in patients, although the outcomes have yet to be reported [25].…”