The implantation effect: delay in seizure occurrence with implantation of intracranial electrodes

Lane, Michael A.; Kahlenberg, Cynthia A.; Li, Z.; Kulandaival, K.; Secore, Karen; Thadani, Vijay M.; Bujarski, Krzysztof A.; Kobylarz, Erik; Roberts, David W.; Tosteson, Tor D.; Jobst, Barbara C.

doi:10.1111/ane.12662

Cited by 14 publications

(16 citation statements)

References 21 publications

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“…Concurrent partial resection of the SOZ in some patients confounds interpretation of the “pure” effects of RNS stimulation, although it is notable that this subgroup of patients had outcomes similar to those for patients who did not undergo resection. There are reports of patients with dramatic reductions in seizure frequency related to implantation of intracranial electrodes even without stimulation . However, given that we included only patients who had been implanted for longer than 6 months, beyond the typical “implant effect” window of 3‐5 months, and that clear electrographic seizures were recorded initially in all patients, we believe that this effect is unlikely to explain our results.…”

Section: Discussionmentioning

confidence: 90%

Responsive neurostimulation for regional neocortical epilepsy

et al. 2019

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Objective Surgical resection of seizure‐producing brain tissue is a gold standard treatment for drug‐resistant focal epilepsy. However, several patient‐specific factors can preclude resective surgery, including a spatially extensive (“regional”) seizure‐onset zone (SOZ). For such patients, responsive neurostimulation (RNS) represents a potential treatment, but its efficacy has not been investigated in this population. Methods We performed a multicenter retrospective cohort study of patients (N = 30) with drug‐resistant focal epilepsy and a regional neocortical SOZ delineated by intracranial monitoring who were treated with the RNS System for at least 6 months. RNS System leads were placed at least 1‐cm apart over the SOZ, and most patients were treated with a lead‐to‐lead stimulation pathway. Five patients underwent partial resection of the SOZ concurrent with RNS System implantation. We assessed change in seizure frequency relative to preimplant baseline and evaluated correlation between clinical outcome and stimulation parameters. Results Median follow‐up duration was 21.5 months (range 6‐52). Median reduction in clinical seizure frequency was 75.5% (interquartile range [IQR] 40%‐93.9%). There was no significant difference in outcome between patients treated with and without concurrent partial resection. Most patients were treated with low charge densities (1‐2.5 µC/cm2), but charge density, interlead distance, and duration of treatment were not significantly correlated with outcome. Significance RNS is a feasible and effective treatment in patients with drug‐resistant regional neocortical seizures. Prospective studies in larger cohorts are necessary to determine optimal lead configuration and stimulation parameters, although our results suggest that lead‐to‐lead stimulation and low charge density may be effective in some patients.

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Section: Discussionmentioning

confidence: 90%

Responsive neurostimulation for regional neocortical epilepsy

et al. 2019

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“…2) and cortical responses may be suppressed for reasons that remain unclear (Lane et al, 2016). This could potentially explain why evoked high gamma activity was more robust at 18.5 MPI than at 2 MPI (Fig.…”

Section: Discussionmentioning

confidence: 99%

Chronic ambulatory electrocorticography from human speech cortex

et al. 2017

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Direct intracranial recording of human brain activity is an important approach for deciphering neural mechanisms of cognition. Such recordings, usually made in patients with epilepsy undergoing inpatient monitoring for seizure localization, are limited in duration and depend on patients’ tolerance for the challenges associated with recovering from brain surgery. Thus, typical intracranial recordings, similar to most non-invasive approaches in humans, provide snapshots of brain activity in acute, highly constrained settings, limiting opportunities to understand long timescale and natural, real-world phenomena. A new device for treating some forms of drug-resistant epilepsy, the NeuroPace RNS® System, includes a cranially-implanted neurostimulator and intracranial electrodes that continuously monitor brain activity and respond to incipient seizures with electrical counterstimulation. The RNS System can record epileptic brain activity over years, but whether it can record meaningful, behavior-related physiological responses has not been demonstrated. Here, in a human subject with electrodes implanted over high-level speech-auditory cortex (Wernicke’s area; posterior superior temporal gyrus), we report that cortical evoked responses to spoken sentences are robust, selective to phonetic features, and stable over nearly 1.5 years. In a second subject with RNS System electrodes implanted over frontal cortex (Broca’s area, posterior inferior frontal gyrus), we found that word production during a naming task reliably evokes cortical responses preceding speech onset. The spatiotemporal resolution, high signal-to-noise, and wireless nature of this system’s intracranial recordings make it a powerful new approach to investigate the neural correlates of human cognition over long timescales in natural ambulatory settings.

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“…Patients undergoing intracranial electrode monitoring for epilepsy must have an adequate number and type of seizure to localize the ictal‐onset zone and proceed with further treatment options such as resection or neurostimulation. Although several methods are utilized to attempt to induce seizures, including strobe lights and sleep deprivation, seizure frequency may decrease immediately after surgery because of anesthesia and implantation effects . These patients must remain in the hospital until enough seizures are captured to localize the ictal‐onset zone, and this can often lead to longer LOS.…”

Section: Discussionmentioning

confidence: 99%

“…Although several methods are utilized to attempt to induce seizures, including strobe lights and sleep deprivation, 9 seizure frequency may decrease immediately after surgery because of anesthesia and implantation effects. 7 These patients must remain in the hospital until enough seizures are captured to localize the ictal-onset zone, and this can often lead to longer LOS. LOS is an important metric to assess bed management and hospital discharge flow, but patients undergoing intracranial monitoring often have extended LOS due to the preceding factors.…”

Section: Discussionmentioning

confidence: 99%

“…Regardless of which invasive electrode strategy is employed, an adequate number and type of seizures are required to be captured to localize the ictal‐onset zone. Although the average implantation time with subdural grid implantation is approximately 1 week, this may vary greatly based on implantation effects and recent anesthesia administration . Patients undergoing invasive electrode monitoring may require a longer length of stay because intracranial recording is predicated on obtaining enough seizures to appropriately localize the ictal‐onset zone, and the time frame to obtain these data is often unpredictable.…”

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confidence: 99%

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