Spinal Cord Stimulation for Pain Relief in Irritable Bowel Syndrome

The primary aim of the study is to investigate if the typical chronic abdominal pain in IBS can be ameliorated by SCS. Secondary aims are possible effects of SCS on diarrhea or constipation, quality of life and side effects, and further to evaluate the feasibility and tolerability of SCS as validated by the willingness of the patients to retain the SCS stimulation equipment.

Eligible patients are selected by a gastroenterologist for the study inclusion criteria: age 18-60, fulfilment of Rome II criteria, abdominal pain episodically reaching > 4 on a 0-10 VAS, and stable symptoms for the past 2 years. A thorough clinical work-up is done to exclude organic disease, including routine blood and electrolyte status, hepatic enzyme function and lactose tolerance test as well as colonoscopy or colon x-ray. Patients with significant somatic or psychiatric co-morbidity will be excluded.

Study design: A quadripolar SCS-lead (Quad-plus®, Medtronic Inc., Minnesota, USA) was implanted via a percutaneous puncture at the Th11/12 level of the dorsal epidural space in local anesthesia with the patient in the prone position. The electrode is advanced to the mid-thoracic level, aiming for a final position around T6-T8, until intraoperative stimulation yields paresthesias covering the abdomen . The electrode is then connected to an impulse generator (Itrel-3®, Medtronic Inc.) implanted subcutaneously in the upper left quadrant of the abdomen. Stimulation frequency will be set to 50 Hz for all patients but other parameters (electrode pole combinations, amplitudes and pulse width) are adjusted and set to produce adequate paresthesias of comfortable intensity.

During the subsequent ongoing trial reprogramming was allowed, if necessary for optimal stimulation.

SCS will be started 2 weeks after surgery. Thereafter patients are randomized to either of two study arms: one starting with SCS for a period of six weeks (A), and another with six weeks without SCS (delayed start) (B). When on active SCS, patients are prompted to stimulate 8-12 h per day. Patients are instructed to increase the stimulation upon pain attack break-through.

After six weeks, patients without stimulation were crossed-over to stimulation and vice versa. After another six weeks both study arms included continued stimulation for additional 12 weeks up to 26 weeks. After a final 2-week period without stimulation the trial is terminated.

During the whole study period patients will record, on a daily basis: 1) number of pain attacks, 2) number of diarrhea episodes, 3) average pain level for the day (0-10) and 4) average quality of life (0-10).

Patients are scheduled for regular controls, at 2, 8, 14, 26 and 28 weeks after implantation. Patient compliance will be ensured, as the impulse generator stores information on the percentage of elapsed time that stimulation has been in use.

At termination of the study participants were offered to keep the implanted SCS system or have it removed.

All patients will be contacted for a structured telephone interview follow-up at a time-point varying between 18 to 78 months after the study termination. A questionnaire was used to assess present pain level, medication, use of the SCS system, side effects and global satisfaction. Patients will also be asked whether they would have participated if they had known the outcome in advance, and if they would recommend a trial of SCS treatment to someone else with similar gastrointestinal problems.

All patients will be evaluated with the hospital anxiety and depression scale (HADS) and a modified version of the gastrointestinal symptom rating scale for IBS (GSRS-IBS).

Inclusion criteria

• age 18-60, Rome II criteria, abdominal pain >4 (0-10 VAS), stable symptoms for >2 years

Exclusion criteria

• other gastrointestinal disease, somatic or psychiatric co-morbidity