Electrical Stimulation of the Anterior Nucleus of the Thalamus for Intractable Epilepsy: A Long‐term Follow‐up Study

Abstract

Summary:Purpose: The anterior nucleus of the thalamus (ANT) modulates temporal lobe and hypothalamic activities, and relays information to the cingulate gyrus and entorhinal cortex. Deep brain stimulation (DBS) of the ANT has been reported to decrease seizure activity in a limited number of human subjects. However, long-term effect of chronic ANT stimulation on such patients remains unknown. We report long-term follow-up results in four patients receiving ANT stimulation for intractable epilepsy.Methods: Four patients underwent stereotactic implantation of quadripolar stimulating electrodes in the bilateral ANT, guided by single-unit microelectrode recording. Electrode location was confirmed by postoperative magnetic resonance imaging (MRI). The stimulator was activated 2-4 weeks following electrode insertion; initial stimulation parameters were 4-5 V, 90-110 Hz, and 60-90 µs. Seizure frequency was monitored and compared with preimplantation baseline frequency. Intelligence quotient (IQ) test and auditory P300 response were performed before and after implantation of electrodes.Results: Four patients (one man with generalized seizures, and three women with partial seizures and secondary generalization) aged 18-45 years old were studied with mean followup period of 43.8 months. The four patients demonstrated a sustained effect of 49% (range, 35-76%) seizure reduction to ANT stimulation. Simple insertion of DBS electrodes (Sham period, no stimulation) produced a mean reduction in seizures of 67% (range, 44-94%). One patient was seizure-free for 15 months with anticonvulsant medications. One patient had a small frontal hemorrhage and a second patient had extension erosion over scalp; no resultant major or permanent neurological deficit was observed. Preoperative IQ index and auditory P300 were not significantly different with those after electrodes implantation.Conclusions: Implantation of electrodes in the ANT and subsequent stimulation is associated with a significant reduction in seizure frequency. However, our study could not differentiate whether the implantation itself, the subsequent stimulation or postimplantation drug manipulation had the greatest impact. These experimental results prompt further controlled study in a large patient population.

Placement of Deep Brain Electrodes in the Dog Using the Brainsight Frameless Stereotactic System: A Pilot Feasibility Study

“…The treatment group of the 110 patients in the SANTE trial showed a median seizure frequency reduction of 29% at 3 months, 41% at 1 year, 56% at 2 years, and 68% by the end of 3 years as compared with baseline. Other, smaller, nonrandomized trials of ANT stimulation also have been performed with 4–6 patients per trial, with seizure frequency reduction of 14–75% 9, 11, 16, 17, 18, 19…”

Chronic high-frequency deep-brain stimulation in progressive myoclonic epilepsy in adulthood-Report of five cases

“…Finally, considering our experiences in this open-pilot DBS study in patients with PME, we strongly recommended further investigation of this therapeutic approach by means of a multicenter study considering off-phases and assessing the effect of the surgical procedure itself by initiating DBS sometime after surgery as it was elegantly performed by others applying DBS in epilepsy (Lim et al, 2007).…”

Possible new avenues in epilepsy treatment: the stimulation techniques deep brain stimulation, vagal nerve stimulation, transcranial magnetic stimulation

“…Stimulation of the anterior nucleus of the thalamus has so far been tested in about 31 patients worldwide with multifocal epilepsy and symptomatic generalised seizures or partial complex [18][19][20][21][22][23]. These studies report that stimulation at a frequency between 90 and 200 Hz, produces a significant reduction of theseizure frequency (≥60%) in 16/31 of the patients.…”