Implantation of an intercostal nerve stimulator for chronic abdominal pain

Abstract

Chronic abdominal pain is not uncommon and can be difficult to manage. We present the case of a 17-year-old man with a 4-year history of chronic abdominal pain. The patient had previously undergone abdominal surgery by way of laparoscopic appendicectomy and right nephrectomy for a mal-rotated kidney. The patient continued to suffer right-sided abdominal pain which was not controlled by analgesia. We report the successful implantation of a right D11 intercostal nerve stimulator to control the patient’s pain. This is the first report of an implantable intercostal nerve stimulator to control intractable chronic abdominal pain.

Implantable peripheral nerve stimulators have been used in the control of chronic pain for over 30 years.¹ Recent results of larger case series suggest that implantable peripheral nerve stimulation devices have good success rates with over 60% of patients reporting significant improvements in their pain and life-style.² Peripheral nerve stimulators are regularly implanted for pain syndromes in the distribution of cranial nerves and the peripheral nerves of the limbs. There are no previous reports of implantable peripheral nerve stimulators to treat chronic abdominal pain. We describe implantation of a D11 intercostal nerve stimulator to treat chronic abdominal pain successfully.

Case history

A 13-year-old boy presented with a history of vague epigastric abdominal pain which spread and became localised to the right iliac fossa over a period of 5 days. The pain was described as a dull ache and was relieved by diclofenac. There was no history of weight loss, diarrhoea, nausea or vomiting, or systemic upset. Examination did not reveal any peritonism and he was initially managed conservatively. The symptoms did not resolve and he was admitted to hospital for further investigation. Ultrasound of the abdomen was unremarkable; laparoscopy revealed a very small amount of old blood in the right iliac fossa and a routine appendicectomy was performed. Histological examination of the appendix revealed mild lymphoid hyperplasia. Pain continued and was located to the right of the mid-line at the level of the umbilicus. Pressure over the kidney and ureter was noted to exacerbate the pain.

A repeat abdominal ultrasound and magnetic resonance imaging scan revealed a mal-rotated right kidney with the ureter facing laterally. Urinalysis and renal function tests were normal. A NM Mag3 Renogram confirmed a mal-rotated right kidney with reduced function (27%) and normal drainage. Upper and lower gastrointestinal endoscopy and a Meckel’s scan did not reveal any abnormalities. Extensive blood tests including liver function, inflammatory markers and eosinophilia serology were all negative.

Two months following the initial onset of abdominal pain, the patient was receiving 40 mg amytryptiline and regular diclofenac, paracetamol and codeine in an attempt to control his pain. Amytryptiline was changed to gabapentin over the next few months but without further success. Eighteen months following his initial presentation, the patient underwent a right nephrectomy through a mid-line abdominal incision. The patient continued to have chronic abdominal pain and 2 years later he was referred to the functional neurosurgical group for evaluation. Two trials of right D11 rhizolysis produced temporary pain relief. The patient elected to undergo surgery for implantation of an intercostals nerve stimulator when he was 17 years old.

Surgical procedure

The patient was placed right side up on the operating and X-ray screening was used to located the right D11 intercostal space. Local anaesthetic (2% lignocaine) was infiltrated and a 1-cm incision made over the posterior end of the D11 rib. A peripheral nerve stimulator with an alternating anode-cathode configuration (Advanced Neuromodulation Systems, Octrode 3186) was inserted along the intercostals nerve and trial stimulation co-localised to the region of pain described by the patient. The stimulator extension wire (Advanced Neuro-modulation Systems, Extension 3383) was attached and the leads externalised through a separate incision. The stimulator settings were optimised (pulse-width 500 μs, frequency 80 Hz, 2–3 mA max) and the stimulator leads were internalised with a rechargeable implantable pulse generator (Advanced Neuromodulation Systems, Rechargeable IPG 3788) in the right flank one week later. A postoperative X-ray confirmed the position of the intercostals nerve stimulator (Fig. 1).

Figure 1.

Chest X-ray showing placement of an intercostal nerve stimulator along the right D11 intercostal nerve.

Clinical results

Prior to surgery, the patient was receiving 300 mg gabapentin, 60 mg codeine q.d.s, paracetamol 1 g q.d.s., and was using a buprenorphine dermal patch. Immediately following implantation of the intercostals stimulator, the patient reported a dramatic reduction in pain and stopped taking codeine. The stimulator was programmed at 500 ms, 80 Hz, 2–3 mA. Within 4 weeks of implantation of the stimulator, the patient had further reduced medication significantly and had stopped using the buprenorphine dermal patch. Codeine had been reduced by 50% and gabapentin was being reduced gradually. At 10-month follow up, the patient was completely pain free and had discontinued all medication.

Discussion

Intercostal nerve stimulation successfully alleviated the chronic abdominal pain in the case described here. The underlying aetiology of chronic abdominal pain in this patient remains elusive. A mid-line incision was carried out for the nephrectomy due to the mal-position of the kidney. It is unlikely, therefore, that the pain was neuropathic secondary to peripheral nerve damage. It is more probable that the pain was visceral in origin, possibly due related to the malpositioned kidney, with referred pain to the D11 dermatome. Peripheral nerve stimulation has been used for inguinal neuropathic pain following hernorrhaphy and peripheral nerve field stimulation has been used previously for chronic abdominal pain.³ In the case reported here, it is probable that the peripheral nerve stimulator has been effective in controlling chronic visceral abdominal pain.

The patient underwent successful radiofrequency rhizolysis (80ºC for 60 s) of the D11 nerve to alleviate the pain temporarily prior to implantation of the stimulator. A trial of rhizolysis might, therefore, be considered in order to establish whether patients would benefit from an intercostal nerve stimulator. The patient was considered for a peripheral nerve stimulator by a multidisciplinary pain team including neuropsychologists. In this case, formal psychological assessment was not deemed necessary. Although there is no empirical evidence that psychological screening before device implantation improves outcome, psychological evaluation should be considered in all cases.⁴ It is theoretically possible that stimulator devices could mask pain from abdominal pathology in future and the risks of this should be taken into account on a patient-by-patient basis.

Chronic abdominal pain following abdominal surgery is not uncommon. Incidence of chronic lower abdominal pain following Pfannenstiel incisions is between 2–4% and has been successfully treated with iliohypogastric and ilio-inguinal neurectomy.⁵ Similarly, peripheral nerve blockade has been successfully employed in paediatric patients with chronic abdominal wall pain.⁶ Nerve stimulators have been employed to guide paravertebral blockade in patients with thoracic myofascial pain syndrome.⁷ However, to date, there have been no reports of using an implantable peripheral nerve stimulator to treat chronic abdominal pain successfully. The case reported here represents the first successful use of an implantable peripheral nerve stimulator to treat chronic abdominal pain. This technique represents a potentially invaluable treatment modality for chronic pain patients refractory to medical management.

Conclusions

Intercostal nerve stimulation for chronic abdominal pain is both feasible and potentially successful intervention. This modality is minimally invasive and should be considered for patients with chronic abdominal pain syndromes whose symptoms are not controlled by medical means.