Sacral neuromodulation for the treatment of detrusor hyperreflexia with impaired contractility (DHIC)

Detrusor hyperactivity with impaired contractility (DHIC) is a common clinical entity that is poorly understood, under-recognized, and difficult to effectively manage. It is a condition in which patients unexpectedly display detrusor overactivity (DO) during storage, yet are unable to mount a sufficient detrusor contraction during voiding to completely empty the bladder. It is theorised that SNM would potentially treat both aspects of DHIC, the DO and poorly contractile bladder. Currently, there are no studies evaluating the efficacy of SNM for DHIC. In this study, we aim to evaluate the efficacy of SNM for treating DHIC. Patients with urodynamically proven DHIC will undergo a two stage surgical procedure performed under general anaesthesia (GA) and then local anaesthesia with sedation. The 1st stage procedure will involve a tined lead insertion into the S3 foramina and corresponding nerve root. This procedure is performed with the patient in the prone position and under GA. This tined lead is connected to an external battery and a trial of SNS. Patients are trialled for 2 weeks (occasionally 3 weeks). Patients stay on the same program for the trial duration, unless their response is lower than a 50% improvement in symptoms. Symptom parameters are measured using a Patient Management Worksheet. For patients with DHIC we initially generally leave them on one program for at least 5 days. At this point if their symptoms have not improved we then consider changing their program. Patients can change their own program during the trial and after consultation. Patients document symptom control for each program. The duration of each programming session will be approximately 20 minutes. The programming will be done by a specialist representative from Medtronic who has specialist training in SNS programming and the senior author of the study. During a trial, patients can access 3 programs stored in their SNS controller. Patients are usually given C1, C2, & C3 or C2, C3 & C4 depending on motor response in theatre, amplitude limit and patient comfort. Different controller program specifications C1: Electrode combination 0-/3+, Time 210 micro seconds, Frequency 25 Hz C2: Electrode combination 1-/3+, Time 210 micro seconds, Frequency 25 Hz C3: Electrode combination 2-/0+, Time 210 micro seconds, Frequency 25 Hz C4: Electrode combination 3-/0+, Time 210 micro seconds, Frequency 25 Hz C5: Electrode combination ,1-/3+, Time 210 micro seconds, Frequency 25 Hz C6: Electrode combination 1-,2-/3+ 2, Time 210 micro seconds, Frequency 25 Hz C6: Electrode combination -,3-/0+, Time 210 micro seconds, Frequency 25 Hz Thus settings be a will adjusted on a case-by-case basis to provide optimal patient symptom relief, minimize patient discomfort, and maximize neurostimulator battery life. Patients that report an improvement of greater than 50% in urgency, urge incontinence, and frequency will be offered a stage 2 procedure. The stage 2 procedure is performed in the lateral position under sedation. If the patient has had an adequate response that the implantable battery is placed in a tissue pocket in the buttock. The duration of SNS is indefinite if the patient has a good response. Adherence to the desired treatment and device function will be check by 6 month interrogation of the Medtronic sacral nerve stimulator.