Case Study: Deep Brain Stimulation in Chronic AN

A case study published by Isabel Arroteia et al in the British Medical Journal (BMJ) reports a case of a 42-year-old woman suffering from refractory chronic anorexia nervosa (AN) of the bulimic subtype for which deep brain stimulation (DBS) was found to be extremely effective.

AN takes a chronic course in up to 21% of patients and does not respond to conventional treatment options. This form is associated with critical metabolic, endocrine, and electrolyte imbalance as well as psychiatric comorbidities. The serious course of the disease in the most severely affected patients justifies invasive treatment options like deep brain stimulation.

The midbrain/ventral tegmental area, ventral striatum (including the nucleus accumbens (NAcc)), medial frontal, and orbitofrontal cortex make up the reward system of the brain, which is believed to be dysfunctional in AN. The neurocircuitry involved in AN is believed to overlap with the one involved in obsessive-compulsive disorder (OCD). As deep brain stimulation (DBS) of the NAcc has efficacy in OCD, the NAcc might also be an effective DBS target in patients with chronic AN.

Case Description

A 42-year-old woman suffering from chronic AN of the bulimic subtype presented with severe AN. The severity of the disease had increased over the years and eventually led to comorbid depression. At the time of presentation, the patient weighed only 32 kg (BMI 12.8 kg/m²) and was compulsively binge eating and purging several times a day. Concurrent metabolic and endocrine disturbances had led to amenorrhea and osteoporosis with severe leucopenia that led to repeated life-threatening infections. The patient had participated in various psychiatric therapies, including behavioral therapy. None of these were able to provide lasting relief of symptoms or weight gain. The patient was then referred to the neurosurgery department for DBS implantation.

Surgical and Postoperative Course

The surgery was uneventful. After the surgery, the patient did not show any new neurological deficits, and wound healing was regular. The postoperative location of DBS electrodes was determined computationally, as shown in figure 1. In-patient psychiatric follow-up was organized.

The first neurosurgical follow-up appointment took place 1 month later. Over the ensuing 12 months, the patient showed consistent weight gain (as shown in the graph) and a decrease in the frequency of binge eating and purging.

As the skin conditions were very atrophic, the patient developed a 1×1 cm large ulceration of the skin over the fixation cap of the left DBS electrode. After a long discussion with the patient, it was decided to continue with a close follow-up. At this point, the patient's menstrual cycle had already normalized.

After 14 months of follow-up, her weight was stable, but she presented with an increase in the frequency of binge eating and purging over the previous months. Stimulation parameters were reduced. The wound over the left burr hole cap remained unchanged. Stimulation parameters were gradually increased in the following months. As the symptoms persisted, at 19 months of follow-up, the patient asked for the stimulation to be turned off.

At 24 months of follow-up, a total weight gain of 10 kg was seen.

Six weeks later, the patient had lost an additional 3 kg of weight and suffered from the persistence of bingeing and purging, with the stimulation still turned off at that point. The patient was then admitted to the emergency room with headaches and signs of infection over the subcutaneous trajectory of the cables and the wound over the left burr hole cap and was treated for the same. The explantation of the DBS system was performed as soon as possible.

Discussion

Compared with ablative methods, DBS implantation comes with an increased risk of infection and disrupted wound healing. On the other hand, DBS is an adjustable and reversible treatment option, allows the patient to maintain control of the recovery process, and thus is a dynamic process in which the patient is actively involved in making ongoing decisions during follow-up.

The authors concluded that if the patient's life is at risk, there is a potential indication for NAcc DBS when conventional treatment modalities recommended by evidence-based guidelines have not been able to durably alleviate the patient's suffering.

Source: BMJ case reports: Fernandes Arroteia I, et al. BMJ Case Rep 2020;13:e239316. doi:10.1136/bcr-2020-239316