Optimizing deep brain stimulation for the treatment of drug-resistant temporal lobe epilepsy: a pilot study

Abstract

OBJECTIVE The authors sought to determine the antiseizure effects of deep brain stimulation (DBS) of the parahippocampal cortex (PHC) for treatment of drug-resistant mesial temporal lobe epilepsy (MTLE). METHODS After a 3-month baseline period, 6 adult patients with drug-resistant MTLE and hippocampal sclerosis (HS) had stereoelectroencephalography (SEEG)–DBS electrodes implanted at the PHC for identification of the seizure onset zone (SOZ). Patients entered an 8-month, randomized, double-blind protocol for DBS, followed by a 12-month open-phase study. Monthly reports of seizure frequency were collected, with separate counting of focal seizures with or without awareness impairment (focal impaired awareness seizures [FIAS] or focal aware seizures [FAS], respectively) and focal evolving to bilateral generalized tonic clonic seizures (GTCS). Stimulation parameters were 130 Hz, 450 μsec, 2.5–3 V, and cyclic stimulation 1 minute on/4 minutes off. RESULTS The total seizure rate decrement during follow-up was 41% (CI 25%–56%), with better seizure control for GTCS (IQR 19%–20%) and FIAS (IQR 0%–16%), with FAS being less responsive (IQR 67%–236%). No neuropsychological deterioration was observed. CONCLUSIONS PHC DBS induced important antiseizure effects in patients with incapacitating FIAS and GTCS, most likely through blocking the propagation of hippocampal-onset seizures. The PHC target can be easily and safely approached due to positioning away from vascular structures, and there was no evidence of DBS-induced cognitive deterioration.

Emerging approaches in neurostimulation for epilepsy

“…An observational study of 25 patients with temporal lobe epilepsy with bilateral ( n = 15 ) or unilateral ( n = 10) implants showed a 91% median seizure reduction for focal impaired awareness seizures [21 ▪ ]. Stimulation was provided continuously at 130 Hz, 300 μs pulse width, with a target of 3 V. Stimulation of the parahippocampus with similar stimulation settings (although with 1 min on, 4 min off) showed a greater than 50% seizure reduction at 12 months for three out of six patients [22].…”

Deep brain stimulation of the subiculum in the treatment for refractory temporal lobe epilepsy due to unilateral mesial temporal lobe sclerosis

“…These observations paved the way for hippocampal DBS for TLE in the early 21st century [4] , [5] , [6] , [7] , [8] , [9] , [10] , [14] . Recent studies have also highlighted the active role of the subiculum and parahippocampal gyrus in the propagation of temporal lobe seizures [10] , [15] . Bondallaz et al conducted a study involving eight patients with refractory MTLE who underwent invasive recordings to place a permanent DBS lead near the ictal focus [7] .…”

“…The above mentioned clinical evidence suggests that the subiculum may be also involved in seizure propagation [9] , [10] , [13] , [14] . Moreover, not only subiculum but also the parahippocampal cortex may be targeted in patients with severe HS and MTLE [15] . In the largest study of hippocampal DBS for MTLE, Cukiert et al found no correlation between the locations of active contacts and seizure reduction [16] .…”

“…Theoretically, patients with non-lesional MTLE may benefit from hippocampal stimulation with leads implanted within the hippocampus proper, and those with lesional TLE may benefit from subicular or parahippocampal stimulation [10] , [15] . The subicular stimulation provided a significant reduction in FBTCS for our patient.…”

A Molecular Toolbox of Positron Emission Tomography Tracers for General Anesthesia Mechanism Research

“…[ 18 F] 28 has also been studied for measuring cortical thickness and neurons, − traumatic brain injury, − and disorders such as epilepsy, − as well as investigating the relationship between age and hearing, stroke, cerebral palsy, psychosis, aversive, awareness, , and healthy . However, despite the advantages of [ 18 F] 28 over [ 11 C] 28 , its widespread use has been hampered by low RCY or unavailability of precursors .…”