28 Chapter 1 Safety considerations In general, potential risks involved in DBS include the risks associated with the surgical procedures, including the small risk (< 1%) of intracranial haemorrhage or infection and the associated neurological consequences (118). In addition, some patients may show some temporary neurological symptoms (e.g. eye movement abnormalities) that generally disappear spontaneously or after some fine-tuning of the stimulator. Patients with AN are predisposed to significant risk of multi-organ dysfunction related to starvation and purging. This can have implications on mortality and morbidity associated with anesthetic complications during DBS implantation (119). Therefore, a thorough pre-operative anaesthetic assessment and evaluation is required to assist the planning of safe peri-operative care. Patients should be rehydrated adequately and any deranged electrolyte levels should be corrected pre-operatively. There is an increased risk of intra-operative hypothermia. Therefore measures should be taken to keep the patient warm during surgery. Doses of most (anaesthetic) drugs should be adjusted for weight. Patients are particularly susceptible to nerve palsies due to their cachexia and loss of cushioning subcutaneous tissue. Therefore they must be placed carefully on the operating table. During the operation, ECG-changes and potassium levels should be monitored carefully to minimize the risk of arrhytmias. To minimize the overall increased risks associated with anaesthesia the weight and somatic condition will be maximally optimized prior to surgery. Lipsman et al. (2013) reported several adverse events in their pilot study on DBS in AN, with one serious DBS-related adverse event (seizure during programming) and the other serious adverse events being related to the underlying illness. One patient in this study developed hypophospataemia and a refeeding delirium (108). It is expected that weight increase following treatment with DBS will be gradual rather than sudden and excessive. Other DBS studies, for example in OCD and depression, showed that improvement of symptoms takes several months (87-89, 108). However, in case of rapid weight gain following successful treatment with DBS, there is a risk of development of a refeeding syndrome (120). Therefore, AN patients treated with DBS should be advised to increase their food intake gradually and under supervision of a dietary consultant. The somatic condition and the potential development of a refeeding syndrome should be closely monitored by a physician.
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