Deep Brain Stimulation of Thalamic Nuclei for Treatment of Intractable Epilepsy

Abstract

Context: Epilepsy is one of the most common serious neurological disorders. Antiepileptic drugs are effective in most of patients, but one third of them are poorly controlled or their seizures are refractory to drug treatment. Resective surgery is the most common form of surgical treatment for uncontrolled seizures, but it can be associated with profound complications that limit its use. Hence, alternative therapeutic options are required. Evidence Acquisition: Deep brain stimulation (DBS) is increasingly used for the treatment of neurological and psychiatric diseases in patients who do not respond to conventional treatment. Significant improvement of well-being (i.e. quality of life) has been observed in patients with Parkinson's disease and obsessive compulsive disorder. As a result of these observations, DBS is now performed in small patient groups for the treatment of many disorders including epilepsy. However, despite its broad therapeutic potential, the appropriate targets for DBS are poorly understood and the application of DBS is most often based on case-reports rather than basic research derived from the laboratory. There are studies suggesting that intractable epileptic seizures can be modified or interrupted by electrical stimulation of subcortical structures including thalamic nuclei. In this review article, we focused on DBS in thalamus to highlight the recent developments and address the perspectives of this approach for the treatment of refractory epilepsy. Results: Anterior and centromedian thalamic nuclei have a potential role in reducing seizure frequency, particularly in patients with partial and generalized tonic clonic seizures, respectively. Stimulus parameters, especially frequency is an essential factor in determination of the effects of stimulation. Moreover, bilateral stimulation of thalamic nuclei in most experimental and clinical studies appeared to be protective against the incidence of seizure. Conclusions: Electrical stimulation of anterior and centromedian thalamic nuclei represents a new alternative option in the treatment of patients with refractory epilepsy, particularly in those with partial and generalized tonic clonic seizures who are not candidates for surgery or do not respond to surgery. Although most studies suggest that bilateral high frequency stimulation of thalamic nuclei is effective in reducing seizure activity, further studies are required to determine optimal parameters and risk/benefit ratio of thalamic nuclei DBS for the treatment of intractable epilepsy.