Diagnostic conscious pain mapping using laparoscopy under local anaesthetic and sedation in general surgical patients

M.G. Tytherleigh, R. Fell*, A. Gordon
Department of General Surgery and Anaesthetics*, Wexham Park Hospital, Slough, UK

Correspondence to: M.G. Tytherleigh, Department of Colorectal Surgery, John Radcliffe Hospital, Oxford, UK Email: matthew@tytherleigh3.fsnet.co.uk

Introduction Methods Results

Discussion Conclusion References

Keywords: Conscious pain mapping, abdominal pain, laparoscopy
Surg J R Coll Surg Edinb Irel., 2 June 2004, 157-160

Background: Patients in whom extensive investigations have failed to identify the cause of abdominal pain present a challenge to surgeons. We present our initial experience of using laparoscopy under local anaesthetic and sedation in the diagnosis of chronic abdominal pain. Methods and Patients:Nine patients with chronic abdominal pain and multiple normal investigations underwent laparoscopy under local anaesthetic and sedation. By touching and grasping intra-abdominal viscera and peritoneum, an attempt was made to reproduce the patient’s pain. Results: Two patients were found to have pain arising from the gall bladder and subsequently underwent laparoscopic cholecystectomy with resolution of their symptoms. A third patient had a clinical presentation of chronic acalculous cholecystitis and a normal laparoscopy. She decided to undergo laparoscopic cholecystectomy, which cured her pain. Another patient had pain arising from the appendix, which resolved after an appendicectomy. Three patients had pelvic adhesions, which caused chronic abdominal pain. After adhesiolysis, one is pain free; the others declined surgery for adhesions and their pain resolved. Conscious pain mapping was negative in two patients. Conclusion: Laparoscopy can be carried out in the conscious patient, who is then usually able to collaborate with the surgeon in establishing the source of the pain experienced during conscious pain mapping. Long-term effectiveness and diagnostic accuracy has not yet been established

Podium presentation in General Surgery: six of the best - Association of Surgeons of Great Britain and Ireland Annual Meeting, Dublin May 2002

INTRODUCTION
Risquez first described, in 1993, the use of laparoscopy under local anaesthetic and sedation (LLAS) for the evaluation of patients with chronic pelvic pain.¹ Since then, the investigation of pelvic pain by LLAS has been well described by gynaecologists. Only recently have non-gynaecological pathologies causing chronic abdominal pain been looked for and diagnosed by LLAS.²

The role of laparoscopy under general anaesthesia in the diagnosis of both acute and chronic abdominal pain has been widely reported. For patients with chronic abdominal pain, who have necessarily undergone multiple investigations, the procedure of conscious pain mapping using LLAS is a logical diagnostic step. This method of managing patients with chronic abdominal pain is well recognised by gynaecologists, but few general surgeons have utilised the technique.

We present our initial clinical experience of the technique of LLAS for the investigation of chronic abdominal pain in the general surgical setting.

METHODS 
Nine consecutive patients under the care of the consultant author, who underwent LLAS between 1998 and 2000, were reviewed retrospectively. All had been referred by their general practioner, the pain clinic or by other consultants within the same hospital. They had all undergone numerous standard investigations for their chronic abdominal pain; blood tests, abdominal ultrasound, oesophagogastroduodenoscopy and colonoscopy having been done as a minimum. Many had underwent a small bowel enema, computerised tomography scanning and laparoscopy under general anaesthesia.

In the operating theatre, the patient was sedated with midazolam (2mg boluses to keep patient relaxed but able to answer questions) and full non-invasive monitoring instituted in the presence of an anaesthetist. Intravenous opiates were also given for pain induced by the procedure, if necessary. Oxygen was delivered by mask. The skin and rectus sheath, at the site of the first cannula, typically just below the umbilicus, were infiltrated with a mixture of 10mls 1% lignocaine and 10mls 0.5% bupivicaine. The linea alba was exposed and the Verres needle was inserted into the peritoneum (semi-open technique). Nitrous oxide was insufflated to a maximum pressure of 8 mmHg and laparoscopy was performed in the head down position using a 5mm laparoscope. Additional 2mm or 5mm ports for instrumentation were appropriately sited under direct vision after infiltration of more local anaesthetic mixture. By touching and grasping intra-abdominal organs and peritoneum, an attempt was made to evoke the patient’s pain: each was asked whether the induced pain was similar in nature and site to the presenting complaint. Depending on the results, and after subsequent discussion in clinic, most patients went on to undergo a successful therapeutic procedures. Patients were followed-up in the out-patient clinic and also by telephone interview.

RESULTS
The findings in the nine patients are summarised in Table 1. Gall bladder pathology was found in three of the nine patients but in one of these, the symptoms had not been reproduced. After discussion, however, and, in view of her characteristic biliary colic symptoms, the patient decided to undergo laparoscopic cholecystectomy and her pain was cured.

Adhesions causing pain were diagnosed in three patients. One had the adhesions divided at laparoscopy under a general anaesthetic and is now pain free. The other two patients, having seen the adhesions that precipitated their chronic abdominal pain and having had an explanation, declined further surgery. Their chronic pain has resolved.

A further patient had adhesions secondary to an appendicectomy but they did not mimic her chronic pain at the time of laparoscopy. At follow-up, 18 months later, her chronic abdominal pain had resolved. One patient had chronic right iliac fossa pain. The appendix was found to be the cause of this pain at laparoscopy and subsequent appendicectomy resulted in a cure.

In one patient with negative findings, the patient was referred to a gastroenterologist. A diagnosis of atypical irritable bowel syndrome was made and treatment was successful. The time taken to insert the ports was similar to other laparoscopic procedures. Conscious pain mapping was completed within 15 minutes for each patient. Only one complication occurred in this series. The initial attempt at LLAS resulted in extraperitoneal insufflation leading to pneumomediastinum and chest pain. The operation was stopped and the patient recovered.

DISCUSSION
Laparoscopy under general anaesthesia has been advocated as an accurate modality for the diagnosis of acute and chronic abdominal pain.³ Performing LLAS and then mapping the patient’s pain with their collaboration has helped in the management of distressed patients who have been misdiagnosed by standard investigations, often including laparoscopy under a general anaesthetic.

The majority of intra-abdominal organs can be manipulated without pain. Zupi et al. (1999) performed LLAS on 20 patients in the investigation of infertility to map out pelvic pain and quantify the level of provoked pain in patients who were pain free.⁴ They were able to show that the highest level of pain was recorded when the Fallopian tube was distended. No pain was elicited when the ovary, omentum and bowel was touched or grasped. They stated that LLAS in women without pathology revealed consistently negative findings, validating the usefulness of this procedure.

It is impressive to see patients, who may not know what is being grasped within their abdomen, express little or no discomfort when the majority of organs and peritoneum are grasped only to pinpoint exactly the structure which, when manipulated, precipitates their chronic pain.

Three patients had their chronic abdominal pain cured by cholecystectomy. The diagnoses of chronic acalculous cholecystitis and cholesterosis should be considered in patients with symptoms of biliary colic or cholecystitis but with a normal ultrasound scan.

One of our patient’s pain was cured by appendicectomy. Almeida and Val-Gallas (1997) described evaluation of the appendix during conscious pain mapping and proposed that the appendix is an under-appreciated source of chronic abdominal pain.⁵ They have reported the first two laparoscopic appendicectomies performed under local anaesthetic following conscious pain mapping.2 We would not proceed immediately to appendicectomy as we have observed a degree of distress and restlessness in patients with peritoneal insufflation that would be accentuated by a longer procedure. There is also a risk of explosion from pockets of nitrous oxide within the abdomen. We prefer the control afforded by a planned procedure under a general anaesthetic.

The association of intra-peritoneal adhesions and chronic abdominal pain has generated considerable controversy as to whether adhesiolysis ameliorates pain. Adhesions between the reproductive organs and the viscera have typically been those that have been shown to cause pain. For the general surgeon adhesions between parietal peritoneum and viscera have been a matter for debate. Originally thought to be physiological and hence disregarded, Keltz et al.(1995) found a high incidence (93%) of unilateral ascending or descending colon to sidewall adhesions in female patients with chronic abdominal pain and relatively few (13%) in the control patients.6 They also showed that these adhesions were more often associated with endometriosis (73%), compared with those without this disorder (7%).

We have shown, in this small series of cases, the therapeutic value of pinpointing the site and cause of chronic abdominal pain and even of negative laparoscopy. Others agree that a negative diagnostic laparoscopy is frequently of benefit to the patient.^7,8 Palter and Olive (1996) suggest that this effect may be enhanced if the patient is allowed to watch their own laparoscopy and we routinely encourage patients to do so.9 Certainly, two of our patients with adhesions, once they had seen them and had them explained, did not require any further treatment.

Only one patient experienced a complication that necessitated the procedure to be abandoned and, despite this occurrence, we were able to repeat the operation successfully at a later date, without any detrimental effect to the patient. All the dangers of laparoscopy must be considered in the decision to carry out LLAS.

Nitrous oxide was used for insufflation, as some will be absorbed and may act as an analgesic both intra-operatively and post-operatively. The evidence in the literature for this, however, is conflicting and the use of nitrous oxide does preclude the use of diathermy and hence any therapeutic procedures.^10,11 The insufflation of carbon dioxide is normally painful and sometimes excruciatingly so.

We present our initial experience of this procedure in the knowledge that it is in its infancy and the long-term efficacy and diagnostic accuracy has not, as yet, been established.

CONCLUSION
Conscious pain mapping using LLAS is a relatively new technique. To the best of our knowledge it has not been described previously in the general surgical literature. Our initial results go some way to show that the procedure may be of benefit in patients with chronic abdominal pain who have had multiple previous investigations with no diagnosis having been established. There is a learning curve for both the surgeon and anaesthetist but the procedure can be well tolerated by the patient and has been unquestionably beneficial in our small series. We plan to continue using conscious pain mapping using LLAS to investigate an increasing number of patients referred with chronic abdominal pain.

REFERENCES
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11. Lipscomb GH, Summitt RL, Jr., McCord ML, Ling FW. The effect of nitrous oxide and carbon dioxide pneumoperitoneum on operative and post-operative pain during laparoscopic sterilization under local anesthesia. J Am Assoc Gynecol Laparosc 1994;2:57-60.

Copyright: 31 March 2004