Deep Brain Stimulation: A Potential Therapy for Epilepsy and Movement Disturbances in Autism Spectrum Disorders?

Within the last ten years, deep brain stimulation has transformed the treatment of a variety of neurological disorders. The principle of deep brain stimulation relies on the continuous electrical stimulation of neural brain structures through implanted electrodes. The therapeutic effects of this technology are most evident in the field of movement disorders where this treatment has become routine for advanced Parkinson’s disease patients. More recently, preliminary studies on the use of this technique in epileptic patients suggest that this therapy may be effective in decreasing seizure activity in these subjects. The use of deep brain stimulation is particularly valuable because of its success in treating the proportion of patients whose conditions are otherwise medically refractive. The present success achieved with the application of deep brain stimulation in the treatment of movement disorders warrants the consideration of its future application to related disorders. These disorders include the group of heterogeneous autism spectrum disorders. Individuals diagnosed with autism spectrum disorders present with unique movement disturbances that are similar to the disturbances that have been defined in most movement disorders. In addition, approximately one third of autistic individuals develop epilepsy and a considerable minority of autistic individuals who do not present with seizures, show epileptiform discharges. This abnormal brain activity has been suggested to be involved in the cognitive, language and behavioral deficits characteristic of these disorders. Despite its success in treating various movement disorders in the clinical setting, the exact mechanism of how deep brain stimulation works is still unclear. Complete understanding of the mechanisms of deep brain stimulation will allow for the optimization of present and future applications of this technology. The first goal of this essay is to discuss the recent findings on the therapeutic effects of deep brain stimulation within the central nervous system, particularly in the treatment of Parkinson’s disease. The second is, specifically, through assessment of the benefits of using this technology in epileptic patients, to propose future experimental studies aimed at investigating the potential therapeutic properties of deep brain stimulation technology in treating autism spectrum disorders. The autism spectrum is the general term used to describe life-long developmental disorders of brain function with differing severity (Tuchman & Rapin, 2002). Autism spectrum disorders (ASDs) may occur in as many as 1/100 to 1/200 live births with diagnosis usually occurring before the age of 3 (Chez, Memon, & Hung, 2004). Approximately 30% of individuals with ASD present with epilepsy/epileptic electroencephalography (EEG) profiles. This epileptic activity might contribute to the regression in language and social skills that occurs in about 40% of individuals with ASD between the ages of 2 and 10 years (Ballaban-Gil & Tuchman, 2000; Di Martino & Tuchman, 2001; Sharifi & Wiznitzer, 2004b; Spence, & Trevathan, 2004). A significant number of individuals with ASD also present with distinct movement disorders that might involve specific motor system dysfunction affecting the basal ganglia among other neural structures (Vilensky, Damasio, & Maurer, 1981). The current classifications of ASDs however, fail to incorporate descriptions of motor disturbance symptoms in children with ASD (Ballaban-Gil & Tuchman, 2000; Brasic, 1999; Leary & Hill, 1996; Marsden, 1984). Additionally these ASD classifications do not consider the occurrence of epilepsy and epileptic activity in affected individuals. At present there is no cure for the disorders on the autism spectrum and treatment usually involves comprehensive behavioral therapy, the goal of which is to equip individuals with skills that will facilitate their daily activities (Nayate, Bradshaw, & Rinehart, 2005). The application of deep brain stimulation (DBS) to treat individuals on the autism spectrum may be a novel and innovative method of treatment. This technology may be particularly useful for the subset of individuals with ASD that present with intractable epilepsy and characteristic movement disorders, and may represent a distinct subgroup of ASD patients. mclaren 168