Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES)

You have been listed for this operation because you have a condition called Anterior Cutaneous Nerve Entrapment Syndrome (A.C.N.E.S). This is after a careful evaluation by Professor Sheen and his colleagues where no other cause for your abdominal pain has been found. You

will have undergone an 18-point ACNES scoring test where you would have scored 12 or above, which is an indicator that surgery may be helpful. Professor Sheen would have provided you with careful counselling in clinic as to why this surgery is being undertaken. Importantly, this diagnosis is made after excluding other causes of pain. If you have any more questions before the operation, please bring them to Professor Sheen’s attention and he will see you in clinic again to ensure that you have a full understanding of the procedure you are about to undergo for an intractable ‘pinpoint’ abdominal pain, where no other cause has been established.

Surgery

On the day of your operation Professor Sheen will review you and ensure that he marks accurately whilst you are lying flat, along with your help, the exact place where you are experiencing pain. If possible, sometimes it is helpful for you to pre-mark where you are experiencing most pain. The surgery involves a small incision and division of the nerves using cautery (electrical heat).

If you remain unsure of the exact location of the pain, then it is reasonable to delay your surgery and for you to monitor exactly where you have most pain.

Surgery can be undertaken in up to three places at any one time.

You would have given a pain score before the operation and the aim will be to try and reduce the pain score, which is on a 1 to 10 scale (see below) by at least two points. Such a reduction is noted to be a successful outcome (ref 1). There are times when there will be no difference in your pain score and also your pain may become worse. It is however, very rare for the pain to become worse. In about 20% of patients the surgery does not resolve the pain. In larger studies about 30% of patients are no better after three months (ref 1).

A further operation can be undertaken with division of the nerves behind the rectus abdominis muscle (posterior nerves). This is a slightly more invasive procedure with division of the rectus sheath and localisation of the nerves behind the rectus muscle. However, the recovery is almost similar to the anterior nerve division operation. Professor Sheen will discuss with you whether this is an option in the future or not and on some occasions, he can undertake both anterior and posterior nerve divisions at the same time, albeit rarely.

Wound care

You will have a small incision (either one or both sides) covered with a tissue glue and sometimes a dressing called Mepore® (Molnycke). Mepore dressing is designed to be air-permeable, comfortable and generally provides a considerably reduced risk of allergic reactions. The Mepore dressing is specially designed not to ‘stick’ to your wound but adhere only to the surrounding skin

so that it can be removed without causing too much discomfort. Please advise your surgeon or nurse if you have experienced any allergic reactions to such dressings in the past so that an alternative dressing can be used

for your wounds. You may also find that you have no dressing and instead the wound is covered with a tissue glue which is hypoallergenic and in two days should also be waterproof. This will stay on for at least 2-3 weeks and eventually just falls away by itself. All the wounds are closed using a dissolvable suture; therefore no sutures (stiches) are required to be removed unless specifically stated. If a dressing is used for your wound, it should ideally stay on for at least 7 days after surgery. If the dressing is removed, becomes wet or falls off, you are advised to reapply another dressing which should remain for up to 7-10 days. You can shower after at least three days, but do not rub soap into your wound and ensure that your wound is kept dry and clean. If you do shower any earlier, please apply a waterproof dressing over the wound. You can take a bath or go swimming at least two weeks after surgery. The wound may be red after a few days and swell. This is part of the normal healing process, and you should continue to carefully monitor your wound. Your wound must be kept dry.

Pain

Some patients describe wound pain. Although you have undergone surgery and may experience some pain, it
is important to inspect the wounds and look for other factors, which may be the cause for the pain including bleeding or redness, indicating a possible infection and a yellow-coloured discharge which could also indicate a possible infection.

In terms of your ACNES pain, this will be different and only time will tell if the ACNES pain that you have been experiencing has been affected or not.

Redness

This can generally represent a simple irritation but if the redness continues then you should consult the hospital ward, your GP surgery or make an appointment to see Prof Sheen in his next available clinic. If either pain or redness should occur and you are not able to contact your GP surgery or the hospital where you had your operation for advise and you are sufficiently concerned, then you are advised to report to your local A&E department.

Stitch/Suture material

Sometimes suture material can be seen protruding, particularly at the ends of the wound. This can usually occur after a few weeks when the wound is almost healed and will usually ‘fall’ away by itself. If the protruding suture material persists then your GP practice nurse

may be able, if possible, to remove it for you or it can be removed by Prof Sheen in his out-patient clinic.

Bruising

This is only sometimes noticed over the wound(s) and is more common in those patients that are on blood thinning medication such as Aspirin. If bruising occurs, then you should not worry as this will settle with time.

Post Op care

You must continue to take the relevant pain medication that you are already taking. This is because you will have a surgical wound. Overtime you will know whether the operation has worked or not as the pain will subside.

It will be important to monitor your pain scores very carefully after surgery.
The wound will heal over the next few weeks and you should be able to carry out normal activities almost immediately including driving so long as the wound pain is not too severe, and you can undertake an emergency stop. If there are any concerns, then please contact
Professor Sheen’s office and if it is out of hours you may need to approach your local GP emergency services or AE department.

VAS Pain score

Please use this to mark your score before and after surgery.

Preop score....................................................................

Post op score (4 weeks) ................................................

(three months) ................................................................

Ref 1
Boelens OB, van Assen T, Houterman S, Scheltinga MR, Roumen RM. A double-blind, randomized, controlled trial on surgery for chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome. Ann Surg. 2013 May;257(5):845-9. doi: 10.1097/SLA.0b013e318285f930. PMID: 23470571.

This information is to be used only as advice. Your surgeon may inform you of any further specific advice that you may require.