Article on Neuropathic Abdominal wall pain treated with medication and Local Injection Therapy
A 54 year old lady attended the clinic with a long history of abdominal pain, which started around 1999, following an operation for the release of a caecal volvulus. Since then, she had had right sided abdominal pain with soreness and tenderness, which started intermittently following the operation, but increasingly had become more constant. She had had multiple therapies and investigations, which included ultrasound scans, x rays, CT, barium enema and other scans. However, no underlying cause for her pain could be found.
She had been under a local Pain Clinic in which she had had a variety of treatments including local Botulinum Toxin A injections performed twice into local trigger points, and also, radiofrequency to the trigger points. She had also had a number of different medications including Codeine, Co-dydramol, Buprenorphine patches, Gabapentin and Diclofenac. Unfortunately, none of the medications tried have been helpful.
When I saw her in the Pain Clinic she was taking Tramadol 100 mg 4 times per day and Paracetamol 500 mg 4 times per day, from which she felt some benefit. She was also using a TENS machine, which she found beneficial. Following her time at the Pain Clinic, she sought a second opinion from a Gastroenterologist and underwent colonoscopy and had colorectal physiology tests performed, which were all normal. In 2006, a laparotomy was performed but only a few fibrous adhesions were found. She also had a course of acupuncture, which was of no benefit, and was ultimately referred to a psychologically based Pain Management Programme.
Clinical Examination findings
On examination of the abdomen, I noted a midline laparotomy scar, a pfannenstiel scar and appendix scar. I note she had generalised tenderness on palpation of the right side of the abdomen associated with allodynia and hyperalgesia.
There was also a specific point of tenderness in the right lower quadrant at the medial end of the appendix scar and above the lateral end of the pfannenstiel incision, where there was extreme tenderness on superficial palpation, and also very severe hyperalgesia. On examination of the spine, flexion, extension and lateral movement were all okay and there was no facet joint or sacroiliac joint tenderness. She mentioned that occasionally on walking, it felt as if there was something catching, like a nerve, and she described it as a very sharp, burning pain.
Diagnosis of neuropathic abdominal wall pain
My impression of this lady was that I felt she had elements of neuropathic pain, given the altered sensation, severity of the pain symptoms and the variable response to treatment. I gave her a full and frank discussion of the nature of neuropathic pain and discussed with her fully whether it was superficial or deep.
My feeling was that it was a much more superficial problem, in particular as the tenderness came on superficial palpation and the local treatment with Botox and the TENS machine were helpful. I explained that I thought that a lot of the local muscle spasm that she had was a local guarding reaction, which is a normal physiological mechanism to protect the body.
Medication for the treatment of neuropathic abdominal wall pain
As to the treatment, the various treatment options were discussed starting with the continuation of the Tramadol and Paracetamol. I also suggested a trial of Pregabalin, starting at 75 mg twice per day and titrating up to 150 mg twice per day over 2 weeks.
In terms of manual treatment, I suggested continuing the TENS machine and I also suggested a TSNS (Transcutaneous Spinal Nerve Stimulator) made by Acticare. We also explored various local nerve block techniques, including local Botulinum Toxin A and the possibility of a combined ilioinguinal iliohypogastric and genitofemoral nerve block.
Ilioinguinal, iliohypogastric and genitofemoral nerve blocks
A week later, this lady came back and had decided to go with the blocks. She had a right ilioinguinal, iliohypogastric and right genitofemoral nerve block, and a right trigger point injection. A total of 160 mg of Depo-Medrone and 15 mls of 1% Lignocaine were used.
She was reviewed in the Pain Clinic 8 weeks later. She had found that for the first month, her symptoms had not changed at all. However, in the second month, she found that her pain scores had dropped significantly from 5-6/10 down to 2/10. There had also been a dramatic reduction in the usage of medication from the previous 1,000 mg of Tramadol 4 times per day down to 500-1,000 mg once per day. Her Paracetamol usage had also reduced. Similarly, I am pleased to report her sleep pattern had improved greatly and she had not been waking up in the middle of the night with pain.
The plan is to review this lady in a month’s time with a view to gently titrating up the dose of Pregabalin. We have talked about adding in other agents and may repeat the local trigger point injection and ilioinguinal iliohypograstric and genitofemoral nerve block.