Nucleus accumbens deep brain stimulation in adult patients suffering from severe and enduring anorexia nervosa (STIMARS): protocol for a pilot study

Abstract

Background: Affecting adolescent and young adults, anorexia nervosa (AN) has the highest death rate of all mental disorders. Effective treatment options are lacking and a significant proportion of patients develop severe and chronic forms of the disease with long-lasting functional impairment. Neurobiology of AN implicates the nucleus accumbens as a core structure of the ventral striatum highly connected to the prefrontal cortex, the insula and the limbic system. Several studies reported promising results of deep brain stimulation for treatment-resistant AN. The aim of this study was to investigate the safety and efficacy of bilateral nucleus accumbens deep brain stimulation in severe and enduring AN.

Methods and analysis: This is a prospective, multicentre, single-arm, open-label, non-randomized pilot trial of bilateral nucleus accumbens deep brain stimulation for severe and enduring AN. Patients will be followed up for 24 months after deep brain stimulation. The main objective of this study is to measure the safety and feasibility of nucleus accumbens deep brain stimulation in this population. The recruitment rate will be collected prospectively. Potential deep brain stimulation efficacy will be monitored by changes in: 1) health-related quality of life; 2) weight; 3) eating disorder symptomatology; 4) neuropsychological changes of cognitive flexibility, habits formation, emotional processing and central coherence; 5) psychiatric comorbidities (anxiety, depression, obsession). Local field potential recordings during an exposure task will be proposed to the patients. Additionally, caregiver quality of life will be assessed.

Discussion: We present the design and rationale for a pilot study investigating the safety of nucleus accumbens deep brain stimulation for treatment resistant anorexia nervosa. This trial will provide an estimated effect size of nucleus accumbens deep brain stimulation for treatment-resistant anorexia nervosa to support future larger-scale clinical trials.

Keywords: electric stimulation therapy; feeding and eating disorders; habits; intraoperative complications; postoperative complications; safety; treatment-resistant; ventral striatum.

Figure 1

Details of the pupillometry. (A) the pupillometry set-up with a chin rest, a computer with a 21″ screen, and an eye tracker; (B) the eye tracker (LiveTrack Fixation Monitor, Cambridge Research Systems Ltd, UK); (C) the first step is to calibrate the camera for pupil tracking during test; (D) different image sets are proposed in random order (neutral images, violent images, sexual images, different silhouette images) with a washout image (a black spot, see middle image) between each test image; (E) different pupil sizes. Pupillometry was performed in a windowless room with low luminosity.

Figure 2

Details of the local field potential recording during an exposure task. (A) the leads are externalized after the surgery. Two days after the surgery, the extensions are connected to an electroencephalogram amplifier, and then to two computers, one for the signal analysis and the other one for the exposure task. (B) the exposure task consists in presenting 120 stimuli. From left to right: each stimulus will be composed of a fixation point (random time from 1 to 2 sec), followed by the image (5 sec), followed by two scales on which the patients will have to rate the induced level of distress and the arousal of the image (visual analog scales from 0 to 5, random order of scale presentation, maximum time for the ratings of 10 sec), followed by a blank screen (random time from 2 to 4 sec).