Faculty Bibliography

PURPOSE OF REVIEW: Cognitive and behavioral treatments for epilepsy offer several advantages, as they are relatively low cost, are non-invasive, lack serious side effects, and facilitate patient participation. Their role in the management of epilepsy, however, is unclear. The following manuscript will critically review the efficacy data regarding psychological treatments for seizure reduction. RECENT FINDINGS: Encouraging results have been found for the cognitive behavioral therapy-based Reiter/Andrews approach and mindfulness or arousal-based programs (e.g., yoga, meditation, relaxation, and biofeedback). Most studies attained responder rates between 45 and 90%. Cognitive and behavioral interventions may be considered as low-risk adjuncts to standard therapies. Efficacy data are limited, however, by small numbers of subjects, inadequate randomization, controls, and blinding, brief trial durations, varying methodologies, and variability in the presentation of results. Additional clinical trials are warranted.

Cognitive deficits, including attention, language, memory, and executive dysfunction, are common in the setting of epilepsy and can greatly impair quality of life. The etiology is often multifactorial and may be due to the underlying seizure disorder, treatment adverse effects, and psychiatric comorbidities, among other factors. Management of cognitive deficits aims to address these underlying etiologies as well as provide rehabilitative strategies. Several investigational therapies are also currently under study. This article examines current and future treatments for cognitive dysfunction in epilepsy.

RATIONALE: Impaired consciousness during seizures may be mediated by ictal propagation to the thalamus. Functions of individual thalamic nuclei with respect to consciousness, however, are largely unknown. The dorsomedial (DM) nucleus of the thalamus likely plays a role in arousal and cognition. We propose that alterations of firing patterns within the DM nucleus contribute to impaired arousal during focal seizures. METHODS: Electroencephalograph data were collected from electrodes within the left DM thalamus and midcingulate cortex (MCC) in a patient undergoing seizure monitoring. Spectral power was computed across ictal states (preictal, ictal, and postictal) and level of consciousness (stupor/sleep vs. awake) in the DM nucleus and MCC. RESULTS: Eighty-seven seizures of multifocal left frontal and temporal onsets were analyzed, characterized by loss of consciousness. At baseline, the left DM nucleus demonstrated rhythmic bursts of gamma activity, most frequently and with greatest amplitude during wakefulness. This activity ceased as ictal discharges spread to the MCC, and consciousness was impaired, and it recurred at the end of each seizure as awareness was regained. The analysis of gamma (30-40Hz) power demonstrated that when seizures occurred during wakefulness, there was lower DM ictal power (p<0.0001) and higher DM postictal power (p<0.0001) relative to the preictal epoch. This spectral pattern was not evident within the MCC or when seizures occurred during sleep. CONCLUSIONS: Data revealed a characteristic pattern of DM gamma bursts during wakefulness, which disappeared during partial seizures associated with impaired consciousness. The findings are consistent with studies suggesting that the DM nucleus participates in cognition and arousal.

OBJECTIVE: Intra-stimulation discharges (IDs) can occur during language mapping, are largely unrecognized, and may precede the occurrence of after-discharges (ADs) and seizures. This study aimed to identify predictors of ID occurrence and determine whether IDs increase the probability of triggered ADs. METHODS: A total of 332 stimulation events performed during language mapping were analyzed in 3 patients who underwent intracranial EEG recordings during evaluations for epilepsy surgery. IDs were identified in 76 stimulation events. The relationships between IDs and the stimulus current intensity, stimulation duration, and proximity to regions of abnormal cortical excitability [characterized by the presence of baseline epileptiform discharges (BEDs)] were determined using regression analysis. RESULTS: The presence of BEDs in close proximity to stimulation, an increase in stimulus intensity by 1 mA, and an increase in stimulation duration by 1s independently increased the odds of triggering IDs by 7.40, 1.37, and 1.39 times, respectively. All IDs were triggered during stimulations in the temporal lobe. The occurrence of IDs increased the odds of triggering ADs 5-fold. CONCLUSIONS: Longer stimulations, higher currents, and the presence of BEDs at the stimulation site increase the probability of ID occurrence, which in turn increases the probability of triggering ADs. SIGNIFICANCE: Attention to IDs may improve the safety and precision of neurophysiologic mapping.

This article primarily represents the contributions of two young investigators to the understanding of the neuropsychological consequences of epilepsy and its treatment. The authors have reviewed two key areas of importance: the complex relationship between cognitive dysfunction and epilepsy and the risks of cognitive dysfunction in children as a consequence of in utero exposure to antiepileptic drug treatment. The work of two young investigators is presented and future research needs are outlined.

The primary aim of this study was to determine whether hippocampal asymmetries in fluorodeoxyglucose (FDG) uptake on preoperative PET scans would predict post-temporal lobectomy verbal memory (VM) decline in patients with left temporal lobe epilepsy. A quantitative asymmetry index (AI) of uptake values within a hippocampal region of interest (ROI) was defined by an automated technique. No statistically significant effect of the hippocampal AI on the outcome measure, the pre- to postsurgical change in Logical Memory Percent Retention, was evident. Post hoc analyses revealed that AIs of the superior and inferior temporal gyri approached significance, however, with relatively greater left-sided preoperative metabolism predicting better VM outcomes. This finding suggests reorganization of function and/or retained function of remaining tissue. Although hippocampal FDG-PET asymmetries did not significantly predict changes in VM, the predictive value of neocortical AIs should be further explored. Automated ROI parcellation provides a feasible tool for use in such investigations.