The methylmalonic acidemias (MMAs) are a group of inborn errors of metabolism resulting in the accumulation of methylmalonic acid in body tissues and fluids. A recognized complication of MMA is bilateral liquefaction of the globus pallidi, resulting in a fulminant total body dystonia of childhood often refractory to medical treatment. This case of total body dystonia due to MMA in a 4-year-old boy had been medically refractory for 15 months. Complete metabolic destructive liquefaction of the pallidi, that is, autopallidotomy, necessitated an alternative, bilateral subthalamic nucleus (STN) target for deep brain stimulation (DBS) with a marked improvement in dystonia and reduction in pain. The case illustrates the efficacy of STN DBS in this condition and the technical challenges in targeting the STN in a small child.

Deep brain stimulation is the surgical treatment modality of choice for otherwise treatment resistant and affective disorders such as dystonia, tremor and Parkinson's disease. Furthermore, DBS is now being used or investigated in the management of other conditions such as chronic pain, depression, obsessive compulsive disorder, Tourette syndrome, obesity, epilepsy and Alzheimer disease.The exact mechanism of action of DBS is not completely understood. The primary target sites vary according to patient's symptoms. The various target sites are subthalamic nucleus, globus pallidus, pars internal and ventralis intermedius nucleus of thalamus.The surgical procedure involves insertion of electrodes into the target area of the brain through a burr hole. This is achieved through a combination of anatomical/imaging techniques (MRI and CT) and neurophysiological verification such as macro stimulation or micro-electrode recording. Once confirmed the electrode is connected via the cable to the pulse generator.The anaesthetic management describes the common and special consideration for awake DBS insertion and insertion under general anaesthesia and postoperative management of these patients.In our institute DBS has been practiced for well over a decade, allowing our multi-disciplinary team to build a large experience spanning both the main and experimental indications and across both the paediatric and adult age groups. The scope of this article is to understand the surgical steps and describe the practical aspect of conducting anaesthesia for patients undergoing DBS including challenges of awake surgery and post-operative care.

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