Children who are not eligible for surgery, or who have had limited surgical success, often attempt the ketogenic diet or vagal nerve stimulation (VNS). A newer approach targets the source of the seizure, using magnets or electricity to stimulate the cortex or deep tissues in the brain.
This can be accomplished by waving a magnet over a stimulator that has been placed in the brain. Once activated, the stimulator alters chemical release in the brain and prevents seizures. Side effects aren’t common, but can include headache, dizziness or ringing ears.
A second method involves implanting the brain with an electrode, which communicates with a neurostimulator inside the chest. The neurostimulator triggers the electrode to zap the source of the seizure, effectively blocking signals from problematic areas of the brain. Some people experience pain where the implant was placed, while others report headaches and feelings of pins and needles. Fewer than 1 in 10 people develop serious side effects such as infection or hemorrhage, which can occur with any type of surgery.
The subcortex is among the safest and most common brain regions targeted by electrical stimulation. Within this region lies the thalamus, a particularly effective area to stimulate due to its connection to the cortex. Common areas targeted by electrical stimulation are described below.
- Centromedian nucleus of the thalamus (CM) stimulation is more effective for patients with generalized epilepsy than focal epilepsy. This procedure can reduce seizures by 70-80 percent in people with tonic-clonic and absence seizures, but outcomes are harder to predict in people with focal seizures or frontal lobe epilepsy.
- Anterior nucleus of the thalamus (ANT) stimulation can control seizures that begin in the temporal lobe, and the effects are relatively long-lasting. Some people experience depression and memory impairment after ANT stimulation, however. This procedure has been approved for use in Europe, but not the United States.
- Hippocampal deep brain stimulation can reduce seizure frequency by 50-60 percent in people with temporal lobe epilepsy. People with normal MRI findings have better seizure outcomes after this type of stimulation than those with hippocampal injuries. Benefits are greatest when both, rather than one, side of the hippocampus are stimulated. Memory decline has not been reported.
Sources:
Cukiert A, Cukiert CM, Burattini JA, Mariani PP and Bezerra DF. 2017. Seizure outcome after hippocampal deep brain stimulation in patients with refractory temporal lobe epilepsy: A prospective, controlled, randomized, double-blind study. Epilepsia. 58(10):1728-1733.
Kim SH, Lim SC, Yang DW, Cho JH, Son BC, Kim J, Hong SB and Shon YM. 2017. Thalamo-cortical network underlying deep brain stimulation of centromedian thalamic nuclei in intractable epilepsy: a multimodal imaging analysis. Neuropsychiatr Dis Treat. 13:2607-2619.
Larkin M, Meyer RM, Szuflita NS, Severson MA and Levine ZT. 2016. Post-Traumatic, Drug-Resistant Epilepsy and Review of Seizure Control Outcomes from Blinded, Randomized Controlled Trials of Brain Stimulation Treatments for Drug-Resistant Epilepsy. Cureus. 8(8): e744. doi: 10.7759/cureus.744.
Martín-López D Jiménez-Jiménez D, Cabañés-Martínez L, Selway RP, Valentín A and Alarcón G. 2017. The Role of Thalamus Versus Cortex in Epilepsy: Evidence from Human Ictal Centromedian Recordings in Patients Assessed for Deep Brain Stimulation. Int J Neural Syst. 27(7):1750010.
Meng D-W, H Liu, A-C Yang, K Zhang and J-G Zhang. 2016. Stimulation of Anterior Thalamic Nuclei Protects Against Seizures and Neuronal Apoptosis in Hippocampal CA3 Region of Kainic Acid-induced Epileptic Rats. Chin Med J (Engl). 129(8): 960–966.
Miguel Pais-Vieira, Amol P. Yadav, Derek Moreira, David Guggenmos, Amílcar Santos, Mikhail Lebedev and Miguel A. L. Nicolelis. 2016. A Closed Loop Brain-machine Interface for Epilepsy Control Using Dorsal Column Electrical Stimulation. Sci Rep. 6: 32814
Sprengers M, Vonck K, Carrette E, Marson AG and Boon P. 2014. Deep brain and cortical stimulation for epilepsy. Cochrane Database Syst Rev. (6):CD008497.
Valentín A, Selway RP, Amarouche M, Mundil N, Ughratdar I, Ayoubian L, Martín-López D, Kazi F, Dar T, Jiménez-Jiménez D, Hughes E and Alarcón G. Intracranial stimulation for children with epilepsy. Eur J Paediatr Neurol. 21(1):223-231.
Wang Z and Wang O. 2017. Eliminating Absence Seizures through the Deep Brain Stimulation to Thalamus Reticular Nucleus. Front. Comput. Neurosci.
