Anterior nuclear deep brain stimulation guided by concordant hippocampal recording

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Anterior nuclear (AN) stimulation has been reported to reduce the frequency of seizures, in some cases dramatically; however, it has not been approved by the US Food and Drug Administration. The anterior nucleus is difficult to target because of its sequestered location, partially surrounded by the ventricle. It has traditionally been targeted by using transventricular or lateral transcortical routes. Here, the authors report a novel approach to targeting the anterior nucleus and neurophysiologically confirming effective stimulation of the target, namely evoked potentials in the hippocampus.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Bilateral AN 3389 electrodes were placed in a novel trajectory followed by bilateral hippocampal 3391 electrodes from a posterior trajectory. Each patient was implanted bilaterally with a Medtronic Activa PC+S device under an investigational device exemption approval. Placement was confirmed with CT. AN stimulation-induced hippocampal evoked potentials were measured to functionally confirm placement in the anterior nucleus.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>Two patients had implantations by way of a novel AN trajectory with concomitant hippocampal electrodes. There were no lead misplacements. Postoperative stimulation of the anterior nucleus with a PC+S device elicited evoked potentials in the hippocampus. Thus far, both patients have reported a &gt; 50% improvement in seizure frequency.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Placing AN electrodes posteriorly may provide a safer trajectory than that used for traditionally placed AN electrodes. In addition, with a novel battery that is capable of electroencephalographic recording, evoked potentials can be used to functionally assess the Papez circuit. This treatment paradigm may offer increased AN stimulation efficacy for medically intractable epilepsy by assessing functional placement more effectively and thus far has proven safe.</jats:p></jats:sec>

Outcome based definition of the anterior thalamic deep brain stimulation target in refractory epilepsy

“…Interestingly, this hypothesis is supported by recent report using posterior trajectory to ANT together with hippocampal DBS capable of registering of evoked potentials [22]. They implanted electrodes along the posterior -anterior axis of ANT and found that only the most anterior contacts within ANT caused hippocampal evoked potentials while more posterior contacts did not.…”

Comparing neurostimulation technologies in refractory focal-onset epilepsy

“…There appears to now be a greater pace of development in lead and IPG technology in DBS, compared with VNS (a mature technology), which may affect costs in the future. Examples are rechargeable IPGs (25-year battery life), closed loop-stimulation (fewer side effects, greater battery life) and directional lead (current steering technology, which may result in better results from suboptimally placed leads, fewer revisions and fewer side effects) 38 39…”

Relationship between Postoperative EEG Driving Response and Lead Location in Deep Brain Stimulation of the Anterior Nucleus of the Thalamus for Refractory Epilepsy

“…Indeed, ventricular involvement in the trajectory is associated with significant targeting errors and an increased requirement for multiple brain passes in DBS [21]. Although paraventricular [13] and posterior inferior [22] approaches may minimize the risk of intraventricular bleeding in a transventricular trajectory, we think that these cannot incorporate the MD, situated posterior and inferior to the ANT, which is intimately involved in the maintenance and propagation of limbic epilepsies [1,23]. Furthermore, the long-term outcome and location of the electrodes have not been systematically investigated.…”