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Changes in verbal and nonverbal memory associated with bilateral hippocampal electrode implantation for epilepsy surgery

J.S. Carvajal-Castrillón, J.F. Zapata-Berruecos, L.M. Galeano-Toro, J. Bareño-Silva, M.E. Jiménez-Jaramillo [REV NEUROL 2012;55:520-527] PMID: 23111990 DOI: https://doi.org/10.33588/rn.5509.2012376

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Volumen 55 | Number 09 | Nº of views of the article 5.637 | Nº of PDF downloads 600 | Article publication date 01/11/2012

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ABSTRACT

INTRODUCTION An appropriate localization of ictal onset zone in refractory temporal lobe epilepsy favors an adequate outcome associated with surgical treatment. When video-electroencephalogram (video-EEG) and magnetic resonance imaging do not provide accurate data to locate ictal onset zone, the use of subdural or deep intracranial electrodes is indicated. Hippocampal electrode placement could generate functional changes in an unaffected hippocampus.

AIM To describe mnesic changes in patients admitted for epilepsy surgery, with previous bilateral hippocampal implantation using depth electrodes.

PATIENTS AND METHODS We identified eight patients undergoing video-EEG using bilateral hippocampal electrodes. Verbal and nonverbal mnesic performance was evaluated before/after the procedure. The following aspects were considered for the analysis: memory lateralization according to intracarotid amobarbital test (Wada test), invasive ictal onset zone, side of resection and pattern of electrocorticographic dissemination.

RESULTS In patients with memory dominance, contralateral to the ictal onset zone, there was an improvement in verbal and nonverbal memory, suggesting that invasive recordings did not impair mnesic skills of the unaffected hippocampus. In patients with bilateral representation of memory, ipsilateral mnesic impairment was associated with the resection. Contralateral improvement in memory was seen when the right side was resected, as opposed to no changes with resections made on the left side, indicating that electrode implantation of unaffected hippocampus did not generate a functional decline.

CONCLUSIONS Based on the preservation of verbal and nonverbal memory after depth electrode placement, invasive recordings of the hippocampus seem to be safe. KeywordsElectroencephalography Implanted electrode Memory Neuropsychology Partial epilepsy CategoriesEpilepsias y síndromes epilépticos Neuropsicología

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Original

Changes in verbal and nonverbal memory associated with bilateral hippocampal electrode implantation for epilepsy surgery