Diagnosis and treatment of pelvic neuropathic pain, with new techniques including laparoscopic pelvic nerves decompression and neurolysis
Treatment of pelvic organ dysfunction includes the stimulation of the genital nerves—GNS therapy
The technique of Laparoscopic Implantation Of Neuroprothesis to the pelvic nerves—LION procedure—for recovery of lost functions, especially in the spinal cord-injured patients and postsurgery pelvic nerve damage
The stimulation of the pelvic autonomic nervous system for prevention and/or treatment of general medical conditions such as osteoporosis, some cardiovascular diseases, or control of sarcopenia—process of aging
The latter includes neurosurgical techniques ranging from decompression, neurolysis, reconstruction, and even nerve resection (e.g., sciatic nerve endometriosis) to pelvic neurofunctional surgery.
The somatic nerves, which innervate the skeletal muscles (voluntary, or red, muscles). These nerves originate in the ventral roots of the spinal cord. The main somatic pelvic nerves involved in pelvic organ functions originate from the sacral plexus and its branches.
FIGURE 18.1 Sacral plexus. (Reprinted from Agur AM, Dalley AF. Grant’s atlas of anatomy, 15th ed. Philadelphia: Wolters Kluwer, 2021.)
The autonomic nerves, which innervate the glands and the smooth muscles (involuntary, or white muscles). These nerves divide into sympathetic nerves (ventral roots of spinal nerves T1-L2) and the parasympathetic nerves (ventral roots of spinal nerves S2-S4/S5).
the plantar flexion of the ankle and consequently the Achilles reflex.
The superior gluteal nerve emerges from the lumbosacral trunk about 2 cm above the greater sciatic notch and leaves the pelvis through the greater sciatic foramen above the piriformis, accompanied by the superior gluteal artery and the superior gluteal vein. This small nerve is extremely important for the stability of the pelvis because it supplies the gluteus medius, the gluteus minimus, and the tensor fasciae latae muscles.
The pudendal nerve is a sensory and somatic nerve that originates from the ventral rami of the 2nd to 4th (and occasionally 5th) sacral nerve roots. After branching from the sacral plexus just proximal to the sacrospinous ligament, the nerve leaves the pelvis through the greater sciatic notch, reenters the pelvic cavity through the lesser sciatic notch, and finally travels to three main regions: the gluteal region, the pudendal canal, and the perineum. It accompanies the internal pudendal vessels upward and forward along the lateral wall of the ischiorectal fossa, being contained in a sheath of the obturator fascia termed the pudendal canal (Alcock canal). The pudendal nerve gives off three distal branches: the inferior rectal nerve, the perineal nerve, and the dorsal nerve of the penis (in males) or the dorsal nerve of the clitoris (in females) (DNP). The pudendal nerve carries sensation from the external genitalia of both sexes and the skin around the anus and perineum as well the motor supply to various pelvic muscles, including the external urethral sphincter and the external anal sphincter. As the bladder fills, the pudendal nerve activates. Contraction of the external sphincter, coupled with that of the internal sphincter, maintains urethral pressure (resistance) higher than normal bladder pressure. The storage phase of the urinary bladder can be switched to the voiding phase either involuntarily (reflexively) or voluntarily.
The sympathetic trunk which stretches on both sides of the spine as a uniform nerve fiber-ganglion cord. The trunk part of the sympathetic trunk joins up with the lumbar and sacral parts. Both lumbar trunks run directly along the medial insertion of the iliopsoas muscle, ventral to the lumbar veins, and have approximately four associated neural ganglia. Anatomically, the left sympathetic trunk lies beside aorta, whereas the right sympathetic trunk remains hidden behind the inferior vena cava and can only be damaged by a retrocaval lymphadenectomy. Damage to the lumbalis of the sympathetic trunk typically leads to homolateral peripheral vasodilation and a warming up of the homolateral foot. The sacral part of the sympathetic trunk runs along the sacrum medial to the sacral foramens. It normally consists of three sacral ganglia that form fibers ventral to the sacrum of the opposite ganglia and show anastomosis to the inferior hypogastric plexus (IHP).
FIGURE 18.2 Pelvic side wall view of sacral and coccygeal nerve plexuses. (Reprinted from Agur AM, Dalley AF. Grant’s atlas of anatomy, 15th ed. Philadelphia: Wolters Kluwer, 2021.)
The IHP (or so called plexus pelvicus). Different plexuses originate from the vegetative solar plexus, orientate themselves along the various collaterals of the aorta, and innervate all the abdominal organs. One of these plexuses is the intermesenteric plexus, which runs ventrolaterally to the aorta between both mesenteric arteries and forms the inferior mesenteric plexus. This plexus dispatches branches that partly accompany the mesenteric arteries and branches that run between the inferior mesenteric artery and the aorta. At the level of the 5th lumbar vertebrae or ventral of the promontorium, the superior hypogastric plexus divides into two inferior hypogastric nerves that run downward into the mesorectum, ventral to the Waldeyer fascia. At the level of the pelvis, the sympathetic fibers build on both the rectum and the IHP. The IHP (also known as the knot from Lee, hypogastric knot, or plexus pelvicus) lies deep in the pelvis in the superior pelvirectal space, lateral to the rectum and the craniodorsal part of the vagina. The plexus shows itself as a net of fibers that form a sacrouterine ligament, also called a rectovaginal pillar.
The iliohypogastric nerve runs anterior to the psoas major on its proximal lateral border, laterally and obliquely on the anterior side of quadratus lumborum. Lateral to this muscle, it pierces the transversus abdominis to run above the iliac crest. It gives several motor branches to these muscles and a sensory branch to skin of lateral hip. Its terminal branch then runs parallel to the inguinal ligament to exit the aponeurosis of the abdominal external oblique above the inguinal ring, where it supplies the skin above the inguinal ligament with the anterior cutaneous branch.
The ilioinguinal nerve runs on the quadratus lumborum caudally to the iliohypogastric nerve. At the level of iliac crest, it pierces the lateral abdominal wall and runs medially at the level of the inguinal ligament, where it supplies motor branches to the transverse abdominis and sensory branches through the external inguinal ring to the skin over the pubic symphysis and the lateral aspect of the labia majora.
The genitofemoral nerve originates from upper part of the lumbar plexus, pierces the psoas major
anteriorly below the iliohypogastric and ilioinguinal nerves, then immediately splits into two branches that run downward on the anterior side of the muscles, lateral to the external iliac artery. The lateral femoral branch is purely sensory and supplies the skin below the inguinal ligament and proximal lateral aspect of the femoral triangle. The genital branch runs in the inguinal canal together with the round ligament. It then sends sensory branches to the skin of the mons pubis and the labia majora.
FIGURE 18.5 Lumbosacral plexus. (Reprinted from Possover M. Neuropelveology: Latest developments in pelvic neurofunctional surgery. Germany: International Society of Neuropelveology, 2015.)
The lateral cutaneous femoral nerve pierces the psoas major on its lateral side and runs obliquely downward below the iliac fascia. Medial to the anterior superior iliac spine, it leaves the pelvic area through the lateral muscular lacuna. In the thigh, it briefly passes under the fascia lata before it breaches the fascia and supplies the skin of the anterior and lateral aspects of the thigh. Injury to the lateral femoral cutaneous nerve can cause anterior and lateral thigh burning, tingling, and/or numbness that increases with standing, walking, or hip extension.
The obturator nerve descends behind the psoas major, then follows the linea terminalis into the lesser pelvis lateral to the external vessels, and then finally leaves the pelvis through the obturator canal. In the thigh, it sends motor branches mainly to the adductor muscles. The anterior branch contributes a terminal sensory branch, which supplies the skin on the medial distal part of the thigh. Obturator nerve injury causes loss of thigh adduction. It is commonly injured during retroperitoneal surgeries for malignancies or endometriosis. It presents with sensory loss in the upper medial thigh and motor weakness in the hip adductors. It can also be injured during paravaginal repairs or transobturator sling placement. The anatomical relationship of the obturator nerve to transobturator tapes can be as close as 2.5 cm away from anterior branch.
The femoral nerve is the largest branch of the lumbar plexus. It provides considerable sensory innervation to the anterior aspect of the thigh and knee and motor innervation to the quadriceps muscles. The femoral nerve runs in a groove between the psoas major and iliacus, giving off branches to both muscles, and exits the pelvis through the medial aspect of the muscular lacuna. In the thigh, it divides into numerous sensory and muscular branches and the saphenous nerve, its long sensory terminal branches, which continues down to the foot. Femoral neuropathy is the most common lumbosacral nerve injury at the time of pelvic surgery. Patients typically report falling when attempting to get out of bed after surgery. In addition to difficulty ambulating, they may also report sensory loss over the anteromedial thigh. The femoral nerve commonly can be compressed by self-retaining retractors as it exits from the psoas muscle, and it can be compressed under the inguinal ligament if the thighs are hyperflexed.
TABLE 18.1 Mechanism of Nerve Injury during Gynecologic Procedures
Such characteristics along with the elasticity of perineurium protect the nerve fibers from injury caused by compression and stretch forces.
FIGURE 18.6 Peripheral nerve. (Reprinted from Handa VL, Van Le L. Te Linde’s operative gynecology, 12th ed. Philadelphia: Wolters Kluwer, 2020.)
Neurapraxia (local conduction block): The injury is caused by transient nerve ischemia. There is no injury to axons and Schwann cells. This type of injury is similar to when the foot falls asleep. Usually, the resolution is within minutes unless the injury is longer causing demyelination.
Axonotmesis (axonal injury with preservation of the protecting Schwann cells): It can affect sensory, motor, and autonomic nerves. Wallerian degeneration begins within 1 to 2 days after injury. Axons grow at 1 mm/day, and typically, these injuries take weeks to months until full recovery.
Neurotmesis (complete disruption of the axon, Schwann cell, and connective tissue): It is caused by complete transection of the nerves. Surgical intervention is required for resolution.
TABLE 18.2 Visceral versus Somatic Pain: Symptoms