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Mesh complications

Post-operative pelvic nerve lesions

Marc Possover,
Juli 13, 2024

Surgery is sometimes the only viable option for the effective medical treatment of a pelvic disorder. However, surgery may carry the risk of a number of complications. Considering the number of pelvic diseases worldwide and the frequency of surgical interventions or pelvic trauma, there is no doubt that many pain symptoms are caused by pelvic nerve injury. One of the most common complications of surgery is bleeding. If there is heavy tissue hemorrhage near the pelvic nerves, the blood can develop into scar tissue over weeks or months after the operation, which can irritate or trap the pelvic nerves. Infections of a hematoma are also possible and are associated with risks of irritation or injury to the pelvic nerves.

The human pelvis has a vast number of pelvic nerves passing through it, especially along the pelvic wall. When performing an operation, there is a risk that these nerves may be damaged or even severed. As a result, those affected have to struggle with sensory disorders such as numbness or even muscle paralysis. In addition, they may experience severe nerve pain called "neuropathic pain" (see below). Since this type of pain practically always becomes chronic and causes functional failures (gait disorder, sexual dysfunction, bladder and intestinal dysfunction, incontinence), it is extremely important to treat nerve injuries quickly after the operation - if there is any evidence of it. This is the main problem: recognizing a complication is not always easy, and admitting it is even more difficult.

What is neuropathic pain?

It goes without saying that pain develops as a result of an operation. So-called "neuropathic pain", which is caused by irritations or injuries of pelvic nerves, is different: it is much more severe and is perceived as hardly bearable. Such pain is usually classified as chronic and is characterized by an extremely intense sensation of pain. On a scale of 1 to 10, those affected usually rate their pain between 8 and 10 - an intensity of pain that is no longer compatible with normal everyday life, both physically and mentally. Even strong painkillers such as morphine preparations provide little relief.

The thought of a possible involvement of the pelvic nerves should always be considered:

  • if any new, unusual pain has developed after the intervention
  • if the pain is not described as severe "period pain" but rather as "electrical pain",
  • if this pain is located in the deep back, buttocks, genitals; especially if this pain radiates
  • downwards, e.g. into the feet.
  • if this pain remains unchanged 2-3 weeks after the procedure, or even becomes worse
  • if numbness occurs in the buttocks, genitals or regions of the legs
  • if movement restrictions of the legs/feet arise (gait difficulties, problems climbing stairs)
  • if new difficulties with urination occur (problems emptying the bladder or urinary incontinence)

If this pain has developed immediately after the surgery, there is obviously a direct mechanical stimulus, or even a lesion, which has occurred during the procedure. However, nerve pain can also occur months or even years after an intervention, i.e. when scar tissue has formed over time as a result of infection, bruising or net implantation. This can irritate or even trap the nerves.

If there is "only" an irritation of the nerve, the regions where the pain is felt feel quite normal. If the nerves are injured or even destroyed, neurological deficits with numbness and/or movement restrictions during walking or difficulties in emptying the bladder or bowels occur.

Which procedures can lead to nerve injuries?

Practically all operations in the pelvis can lead to irritation or injury of the pelvic nerves - including pelvic radiation. Some surgeries, however, put patients at greater risk than others: Surgeries near the pelvic wall or groin involve the risk of damaging the pelvic nerves, which run deep along the pelvic wall or abdominal wall. On the one hand the pelvic nerves can be damaged directly during the operation, on the other hand the formation of scar tissue or atypical blood vessels is possible months or years later. This can lead to friction and mechanical irritation of the pelvic nerves. These "high-risk operations" include oncological procedures, endometriosis operations and prolapse operations, especially in combination with net implantations.

Prolapse operations with net inlays

Prolapse operations with mesh inserts are particularly risky interventions with regard to possible injuries of the pelvic nerves. The aim of prolapse operations is to correct sagging problems and improve the functions of the affected organs such as the vagina, bladder and rectum. The procedure should be as non- invasive as possible, should not cause complications and should have a low recurrence rate.

Nets, also known as meshes, have been used for over twenty years now.

In 2011, reliable studies on the use of nets in the treatment of uterine prolapse and urinary incontinence were presented. In July 2011, the FDA (U.S. Food and Drug Administration) published a much discussed and controversial warning on the use of vaginal nets. More than 1500 recorded complications over a period of three years led to the statement that vaginal nets expose patients to an increased risk without any proven benefit compared to prolapse surgery, which had not previously been net-based.

Mesh inlays are still part of the repertoire of prolapse surgery, but must be viewed critically. Such interventions, like many other operations, can lead to complications in the area of the nerves. However, Prof. Possover, who has been treating such complications for more than ten years, has found that in most cases it is not the net that is responsible for the pain, but the incorrect positioning of the mesh: it is often too close to or even directly on the pelvic nerves. Obviously, the simplification of prolapse operations with mesh implantation, but also the possibility of using "operation kits", has led many surgeons to perform these operations without having the necessary expertise in the anatomy of the pelvic nerves. It would therefore not be right to make a taboo of operations with mesh inserts, but every surgeon must be conscious of the risk-benefit ratio of using mesh. The surgeon must carefully consider whether a mesh insert has clear advantages over the classic operation and must be able to show the patient these correlations adequately and clearly.

The group of "high risk surgeries" mainly includes interventions with mesh inserts during vaginal interventions to treat bladder or bowel prolapse, but also at the coccyx to fix the vaginal stump high. The same risks are associated with mesh inserts in rectal prolapses (this procedure is also called "rectopexy"). Vaginal surgery is performed near the pudendal nerve, the most important nerve for the pelvic floor and genitals. Injury to this nerve leads to burning pain in the perineum, vulva and anal area, making sitting impossible. Implantations of a net above the pelvic floor, by laparoscopy or by abdominal incision, involve the risk of damaging the roots of the sciatic nerve, so that in addition to burning pain in the genitals, pain can also occur in the deep back, buttocks or legs ("lumbago").

Net implantations for the treatment of inguinal hernias

According to current studies, 15-20% of patients who have undergone inguinal hernia surgery also suffer from nerve pain. Nerve pain can occur immediately following surgery or months or even years later. These patients describe burning pain in the groin, depending on which nerve is affected, radiating to the genitals, thighs or even back.

Oncological interventions

In oncological surgery (cancer surgery), the pelvic lymph nodes usually have to be removed. As they cover the pelvic nerves, these operations can cause surgical damage. Particularly at risk is the obturator nerve, whose damage leads to the difficulty of raising the thigh (adduction). The formation of a so-called lymphocele, an accumulation of lymph fluid, can also cause irritation of the pelvic nerves.

Endometriosis surgery

Procedures for the treatment of endometriosis, especially when it is a "deep infiltrating endometriosis", involve the risk of injury to the pelvic nerves. If the surgeon is not familiar with the recognition and preservation of the bladder nerves, bladder emptying disorders often occur after such operations, which in the worst case force the patient to empty the bladder using a catheter (self-catheterisation). If the endometriosis grows near the pelvic nerves (obturator nerve, sciatic nerve, sacral plexus) and if the surgeon does not have sufficient knowledge of the anatomical position and relations of these nerves to each other, nerve injuries may also occur. Depending on the type or severity of the damage, this can result in pain in the buttocks, deep back, genitals (vulvodynia), or in the rectum region (pudendal pain), up to the coccyx (coccygydynia) and pain in the legs (sciatica). Problems such as a frequent urge to urinate or the " false sensation of having to go to the toilet " often arise as well.

The Alcock´s Canal Syndrome

The classic cause of this syndrome is the continuous compression of the nerve in the Alcock´s canal by the bicycle saddle in cyclists or by sitting continuously for long periods in certain occupational groups. 70% of affected patients are female. Irritation of the nerve can occur in various situations:

  • mechanical pressure of a vaginal hematoma or abscess after a traumatic vaginal birth
  • The nerve is trapped at birth between the child's head and the pelvic wall. High-risk births include those where there is protracted labour, the delivery of children weighing more than 4 kg, and the use of forceps and suction bells.

Another common cause is the direct injury of the nerve during a prolapse operation with vaginal elevation at the lateral pelvis. This operation is also called "sacropsinal fixation according to Armreich-Richter". The classical pain symptomatology in the right buttock region, which is described by the patients after the operation, is mostly due to the tension of the fixation. However, if this pain does not subside after a few weeks but rather increases, if sitting becomes impossible or if additional burning pain develops in the perineal area or in the genitals, Alcock´s Canal Syndrome and the associated joint fixation of the affected nerve must be systematically considered.

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