Changes in motor cortex excitability with stimulation of anterior thalamus in epilepsy

Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) for the treatment of neurologic diseases has markedly increased in popularity over the past 15 years. This review primarily focuses on movement disorder applications and efficacy of DBS, but also briefly reviews other promising new and old uses of DBS.

REVIEW SUMMARY

A multidisciplinary team consisting of a movement disorders neurologist, a functional neurosurgeon, and a neuropsychologist optimally selects patients for DBS. Patients must be significantly disabled despite optimal medical therapy and be cognitively healthy without significant psychiatric disorders. Although this surgery is elective, it should not be withheld until the patient suffers marked loss of quality of life. Patients must have support from caregivers and postoperatively multiple DBS programming visits may be required. DBS of the subthalamic nucleus (STN) and the globus pallidus pars interna (GPi) significantly improves motor performance, activities of daily living, and quality of life in advanced Parkinson disease. In addition, STN DBS allows for marked reductions of antiparkinson medication. Stimulation of the ventralis intermedius nucleus of the thalamus is an effective treatment for essential tremor with sustained long-term effects. The GPi may be the preferred site of stimulation for dystonia with movement scores typically improved by 75% in patients with primary dystonia.

CONCLUSIONS

DBS is an effective surgical treatment for movement disorders with sustained long-term benefits. Further research is ongoing to better understand the mechanism of DBS, refine the hardware to improve efficacy and reduce adverse effects, and identify additional applications and new anatomic targets.

Electrical Control of Epileptic Seizures

SUMMARY

Epilepsy is among the most common neurologic disorders, yet it is estimated that about one third of patients do not respond favorably to currently available drug treatments and up to 50% experience major side effects of these treatments. Although surgical resection of seizure foci can provide reduction or cessation of seizure incidents, a significant fraction of pharmacologically intractable seizure patients are not considered viable candidates for such procedures. Research advances in applying electrical stimulation as an alternative treatment for intractable epilepsy have been reported. The primary focus of these studies has been the search for optimized stimulation protocols by which to electrically suppress, revert or prevent seizures. In this review, the authors discuss some of the promising results that have been achieved. These results are organized in three broad categories based on how such protocols are generated. They focus on how information of the electrical activity in the brain is incorporated in the control schemes, namely: open loop, semiclosed loop, and closed loop protocols. Benefits, potential promises, and challenges of these different control techniques are discussed.