The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform

Dean K Naritoku - One of the best experts on this subject based on the ideXlab platform.

  • effects of seizure severity and seizure repetition on Postictal cardiac arrhythmia following maximal electroshock
    Experimental Neurology, 2003
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Convulsive seizures triggered by maximal electroshock (MES) induce profound abnormalities in neural regulation of cardiac rhythm that are manifested by a period of marked cardiac arrhythmia in the immediate Postictal State. It is not known whether seizure severity or seizure experience may influence the duration of cardiac arrhythmia in the Postictal State. We varied the duration of MES administered to rats to vary seizure severity, as measured by the extensor to flexion (E/F) ratio. In separate experiments, rats were subjected to daily MES. Finally, we pretreated rats with ketamine prior to MES to block seizures hindlimb extension. In all animals, the R-R interval was plotted on the tachogram, and the duration of the arrhythmia was measured. Increases in MES duration increased significantly the E/F ratio and prolonged significantly the Postictal cardiac arrhythmia. Repetition of MES caused a kindling effect with respect to seizure severity resulting in a significant increase of the E/F ratio and significant increases in the duration of Postictal arrhythmia. Blocking of the hindlimb extension by ketamine abolished arrhythmia suggesting that the arrhythmia is not caused directly by MES. Severity of tonic convulsive seizures is a determinant of disordered cardiac autonomic regulation and directly influences the duration of cardiac arrhythmia during the immediate Postictal State following MES. Seizure repetition also increases abnormalities of Postictal neural regulation of the heart, but further studies are needed to determine whether this effect is independent of seizure severity increases.

  • cardiac dysrhythmia associated with the immediate Postictal State after maximal electroshock in freely moving rat
    Epilepsia, 2002
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Summary:  Purpose: Cardiac autonomic changes accompany complex partial seizures and generalized tonic–clonic seizures, and participate, at least partially, in the sudden and unexpected death in epilepsy (SUDEP). The analysis of the heart rate variability (HRV) is one of the simplest ways of providing insight into autonomic functions. The entropy quantifies the repetition of complex patterns in a signal and refers to systems randomness, regularity, and predictability. Clinical investigations have reported that entropy decreases in patients with a high risk of sudden cardiac death. The goal of this study was to evaluate the effects of the maximal electroshock (MES) on the entropy of HRV, monitored in the immediate Postictal stage in the model of the freely moving rat. Methods: Entropy changes were correlated with the high and low frequencies of spectral analysis, which reflect the participation of the sympathetic and parasympathetic activities. Results: MES-induced arrhythmia is characterized by an HRV increase, an imbalance in favor of the parasympathetic activity, and a decrease in the entropy. Entropy decrease was restricted to the duration of the arrhythmia, suggesting that the Postictal arrhythmia may be associated with a higher risk of lethal cardiac complications. Nevertheless, entropy changes did not correlate with spectral changes. Conclusions: The results suggest that the imbalance demonstrated in the spectral domain explains only partially the contribution of each autonomic system in the complexity of the heart rate during the Postictal State.

Olivier Darbin - One of the best experts on this subject based on the ideXlab platform.

  • effects of seizure severity and seizure repetition on Postictal cardiac arrhythmia following maximal electroshock
    Experimental Neurology, 2003
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Convulsive seizures triggered by maximal electroshock (MES) induce profound abnormalities in neural regulation of cardiac rhythm that are manifested by a period of marked cardiac arrhythmia in the immediate Postictal State. It is not known whether seizure severity or seizure experience may influence the duration of cardiac arrhythmia in the Postictal State. We varied the duration of MES administered to rats to vary seizure severity, as measured by the extensor to flexion (E/F) ratio. In separate experiments, rats were subjected to daily MES. Finally, we pretreated rats with ketamine prior to MES to block seizures hindlimb extension. In all animals, the R-R interval was plotted on the tachogram, and the duration of the arrhythmia was measured. Increases in MES duration increased significantly the E/F ratio and prolonged significantly the Postictal cardiac arrhythmia. Repetition of MES caused a kindling effect with respect to seizure severity resulting in a significant increase of the E/F ratio and significant increases in the duration of Postictal arrhythmia. Blocking of the hindlimb extension by ketamine abolished arrhythmia suggesting that the arrhythmia is not caused directly by MES. Severity of tonic convulsive seizures is a determinant of disordered cardiac autonomic regulation and directly influences the duration of cardiac arrhythmia during the immediate Postictal State following MES. Seizure repetition also increases abnormalities of Postictal neural regulation of the heart, but further studies are needed to determine whether this effect is independent of seizure severity increases.

  • cardiac dysrhythmia associated with the immediate Postictal State after maximal electroshock in freely moving rat
    Epilepsia, 2002
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Summary:  Purpose: Cardiac autonomic changes accompany complex partial seizures and generalized tonic–clonic seizures, and participate, at least partially, in the sudden and unexpected death in epilepsy (SUDEP). The analysis of the heart rate variability (HRV) is one of the simplest ways of providing insight into autonomic functions. The entropy quantifies the repetition of complex patterns in a signal and refers to systems randomness, regularity, and predictability. Clinical investigations have reported that entropy decreases in patients with a high risk of sudden cardiac death. The goal of this study was to evaluate the effects of the maximal electroshock (MES) on the entropy of HRV, monitored in the immediate Postictal stage in the model of the freely moving rat. Methods: Entropy changes were correlated with the high and low frequencies of spectral analysis, which reflect the participation of the sympathetic and parasympathetic activities. Results: MES-induced arrhythmia is characterized by an HRV increase, an imbalance in favor of the parasympathetic activity, and a decrease in the entropy. Entropy decrease was restricted to the duration of the arrhythmia, suggesting that the Postictal arrhythmia may be associated with a higher risk of lethal cardiac complications. Nevertheless, entropy changes did not correlate with spectral changes. Conclusions: The results suggest that the imbalance demonstrated in the spectral domain explains only partially the contribution of each autonomic system in the complexity of the heart rate during the Postictal State.

John R Hodges - One of the best experts on this subject based on the ideXlab platform.

  • transient epileptic amnesia a description of the clinical and neuropsychological features in 10 cases and a review of the literature
    Journal of Neurology Neurosurgery and Psychiatry, 1998
    Co-Authors: Adam Zeman, Simon Boniface, John R Hodges
    Abstract:

    OBJECTIVES To clarify the clinical and neuropsychological aspects of transient epileptic amnesia (TEA) based on 10 personally studied cases as well as review of 21 previously published cases; and to propose tentative diagnostic criteria for the diagnosis of TEA. METHODS All 10 patients and informants underwent a standardised clinical interview. The radiological and neurophysiological (EEG) data were also reviewed in all cases. The diagnosis of transient epileptic amnesia was made on the basis of the following criteria: (1) there was a history of recurrent witnessed episodes of transient amnesia; (2) cognitive functions other than memory were judged to be intact during typical episodes by a reliable witness; (3) there was evidence for a diagnosis of epilepsy. This evidence was provided by either ( a ) wake or sleep EEG, or ( b ) the co-occurrence of other seizure types (if their roughly concurrent onset or close association with episodes of transient amnesia suggested a connection), or ( c ) a clear cut response to anticonvulsant therapy, or by a combination of these three factors. In addition all patients were administered a comprehensive neuropsychological test battery designed to assess verbal and non-verbal anterograde memory and retrograde memory for famous personalities and personal events. Their results were compared with those of 25 age and IQ matched normal controls. RESULTS TEA usually begins in later life, with a mean age of 65 years in this series. Episodes are typically brief, lasting less than one hour, and recurrent, with a mean frequency of three a year. Attacks on waking are characteristic. Repetitive questioning occurs commonly during attacks. The anterograde amnesia during episodes is, however, often incomplete so that patients may later be able to “remember not being able to remember”. The extent of the retrograde amnesia during attacks varies from days to years. Most patients experience other seizure types compatible with an origin in the temporal lobes, but transient amnesia is the only manifestation of epilepsy in about one third of patients. Epileptiform abnormalities arising from the temporal lobes are most often detected on interictal sleep EEG. Despite normal performance on tests of anterograde memory, many patients complain of persistent interictal disturbance of autobiographical memory, involving a significant but variable loss of recall for salient personal episodes. The epochs affected may predate the onset of epilepsy by many years. CONCLUSIONS TEA is an identifiable syndrome and comprises episodic transient amnesia with an epileptic basis, without impairment of other aspects of cognitive function. Future studies should consider the question of whether TEA reflects ictal activity or a Postictal State, and the mechanism of the persistent autobiographical amnesia. It is hypothesised that the latter may result in part from impairment of very long term memory consolidation as a result of epileptic activity in mesial temporal structures.

Doris J Casebeer - One of the best experts on this subject based on the ideXlab platform.

  • effects of seizure severity and seizure repetition on Postictal cardiac arrhythmia following maximal electroshock
    Experimental Neurology, 2003
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Convulsive seizures triggered by maximal electroshock (MES) induce profound abnormalities in neural regulation of cardiac rhythm that are manifested by a period of marked cardiac arrhythmia in the immediate Postictal State. It is not known whether seizure severity or seizure experience may influence the duration of cardiac arrhythmia in the Postictal State. We varied the duration of MES administered to rats to vary seizure severity, as measured by the extensor to flexion (E/F) ratio. In separate experiments, rats were subjected to daily MES. Finally, we pretreated rats with ketamine prior to MES to block seizures hindlimb extension. In all animals, the R-R interval was plotted on the tachogram, and the duration of the arrhythmia was measured. Increases in MES duration increased significantly the E/F ratio and prolonged significantly the Postictal cardiac arrhythmia. Repetition of MES caused a kindling effect with respect to seizure severity resulting in a significant increase of the E/F ratio and significant increases in the duration of Postictal arrhythmia. Blocking of the hindlimb extension by ketamine abolished arrhythmia suggesting that the arrhythmia is not caused directly by MES. Severity of tonic convulsive seizures is a determinant of disordered cardiac autonomic regulation and directly influences the duration of cardiac arrhythmia during the immediate Postictal State following MES. Seizure repetition also increases abnormalities of Postictal neural regulation of the heart, but further studies are needed to determine whether this effect is independent of seizure severity increases.

  • cardiac dysrhythmia associated with the immediate Postictal State after maximal electroshock in freely moving rat
    Epilepsia, 2002
    Co-Authors: Olivier Darbin, Doris J Casebeer, Dean K Naritoku
    Abstract:

    Summary:  Purpose: Cardiac autonomic changes accompany complex partial seizures and generalized tonic–clonic seizures, and participate, at least partially, in the sudden and unexpected death in epilepsy (SUDEP). The analysis of the heart rate variability (HRV) is one of the simplest ways of providing insight into autonomic functions. The entropy quantifies the repetition of complex patterns in a signal and refers to systems randomness, regularity, and predictability. Clinical investigations have reported that entropy decreases in patients with a high risk of sudden cardiac death. The goal of this study was to evaluate the effects of the maximal electroshock (MES) on the entropy of HRV, monitored in the immediate Postictal stage in the model of the freely moving rat. Methods: Entropy changes were correlated with the high and low frequencies of spectral analysis, which reflect the participation of the sympathetic and parasympathetic activities. Results: MES-induced arrhythmia is characterized by an HRV increase, an imbalance in favor of the parasympathetic activity, and a decrease in the entropy. Entropy decrease was restricted to the duration of the arrhythmia, suggesting that the Postictal arrhythmia may be associated with a higher risk of lethal cardiac complications. Nevertheless, entropy changes did not correlate with spectral changes. Conclusions: The results suggest that the imbalance demonstrated in the spectral domain explains only partially the contribution of each autonomic system in the complexity of the heart rate during the Postictal State.

Adam Zeman - One of the best experts on this subject based on the ideXlab platform.

  • transient epileptic amnesia a description of the clinical and neuropsychological features in 10 cases and a review of the literature
    Journal of Neurology Neurosurgery and Psychiatry, 1998
    Co-Authors: Adam Zeman, Simon Boniface, John R Hodges
    Abstract:

    OBJECTIVES To clarify the clinical and neuropsychological aspects of transient epileptic amnesia (TEA) based on 10 personally studied cases as well as review of 21 previously published cases; and to propose tentative diagnostic criteria for the diagnosis of TEA. METHODS All 10 patients and informants underwent a standardised clinical interview. The radiological and neurophysiological (EEG) data were also reviewed in all cases. The diagnosis of transient epileptic amnesia was made on the basis of the following criteria: (1) there was a history of recurrent witnessed episodes of transient amnesia; (2) cognitive functions other than memory were judged to be intact during typical episodes by a reliable witness; (3) there was evidence for a diagnosis of epilepsy. This evidence was provided by either ( a ) wake or sleep EEG, or ( b ) the co-occurrence of other seizure types (if their roughly concurrent onset or close association with episodes of transient amnesia suggested a connection), or ( c ) a clear cut response to anticonvulsant therapy, or by a combination of these three factors. In addition all patients were administered a comprehensive neuropsychological test battery designed to assess verbal and non-verbal anterograde memory and retrograde memory for famous personalities and personal events. Their results were compared with those of 25 age and IQ matched normal controls. RESULTS TEA usually begins in later life, with a mean age of 65 years in this series. Episodes are typically brief, lasting less than one hour, and recurrent, with a mean frequency of three a year. Attacks on waking are characteristic. Repetitive questioning occurs commonly during attacks. The anterograde amnesia during episodes is, however, often incomplete so that patients may later be able to “remember not being able to remember”. The extent of the retrograde amnesia during attacks varies from days to years. Most patients experience other seizure types compatible with an origin in the temporal lobes, but transient amnesia is the only manifestation of epilepsy in about one third of patients. Epileptiform abnormalities arising from the temporal lobes are most often detected on interictal sleep EEG. Despite normal performance on tests of anterograde memory, many patients complain of persistent interictal disturbance of autobiographical memory, involving a significant but variable loss of recall for salient personal episodes. The epochs affected may predate the onset of epilepsy by many years. CONCLUSIONS TEA is an identifiable syndrome and comprises episodic transient amnesia with an epileptic basis, without impairment of other aspects of cognitive function. Future studies should consider the question of whether TEA reflects ictal activity or a Postictal State, and the mechanism of the persistent autobiographical amnesia. It is hypothesised that the latter may result in part from impairment of very long term memory consolidation as a result of epileptic activity in mesial temporal structures.