Seizure recurrence following epilepsy surgery: is post-operative EEG helpful?

OBJECTIVES: We examined whether the relationship between interictal epileptiform discharges (IED) on post-operative EEG and seizure recurrence after epilepsy surgery was different in patients with neocortical and mesiotemporal resections. METHODS: We reviewed the records of 93 consecutive patients who underwent epilepsy surgery at our center and who had adequate post-operative follow-up and a post-operative EEG to determine the type of surgery, the recurrence of seizures and the presence of IED on post-operative EEG. RESULTS: Chi-square test revealed that for the entire group, there was a significant relationship between the presence of IED and seizure recurrence. However, this relationship was significant in neocortical surgery but not in mesiotemporal surgery. Time distribution of seizure recurrence revealed that in more than half the cases, seizures recurred with the first 3 months. Time distribution was not influenced by the presence of IED. CONCLUSIONS: This study revealed that IED on early post-operative EEG correlate with seizure recurrence in neocortical but not mesiotemporal surgeries and may be used to guide patient counseling in this group of patients.

Controlled clinical trial of dichloroacetate for treatment of congenital lactic acidosis in children.

OBJECTIVE: Open-label studies indicate that oral dichloroacetate (DCA) may be effective in treating patients with congenital lactic acidosis. We tested this hypothesis by conducting the first double-blind, randomized, control trial of DCA in this disease. METHODS: Forty-three patients who ranged in age from 0.9 to 19 years were enrolled. All patients had persistent or intermittent hyperlactatemia, and most had severe psychomotor delay. Eleven patients had pyruvate dehydrogenase deficiency, 25 patients had 1 or more defects in enzymes of the respiratory chain, and 7 patients had a mutation in mitochondrial DNA. Patients were preconditioned on placebo for 6 months and then were randomly assigned to receive an additional 6 months of placebo or DCA, at a dose of 12.5 mg/kg every 12 hours. The primary outcome results were (1) a Global Assessment of Treatment Efficacy, which incorporated tests of neuromuscular and behavioral function and quality of life; (2) linear growth; (3) blood lactate concentration in the fasted state and after a carbohydrate meal; (4) frequency and severity of intercurrent illnesses and hospitalizations; and (5) safety, including tests of liver and peripheral nerve function. OUTCOME: There were no significant differences in Global Assessment of Treatment Efficacy scores, linear growth, or the frequency or severity of intercurrent illnesses. DCA significantly decreased the rise in blood lactate caused by carbohydrate feeding. Chronic DCA administration was associated with a fall in plasma clearance of the drug and with a rise in the urinary excretion of the tyrosine catabolite maleylacetone and the heme precursor delta-aminolevulinate. CONCLUSIONS: In this highly heterogeneous population of children with congenital lactic acidosis, oral DCA for 6 months was well tolerated and blunted the postprandial increase in circulating lactate. However, it did not improve neurologic or other measures of clinical outcome.

Affect in patients with epilepsy undergoing video/EEG monitoring: retrospective versus momentary assessment and temporal relationship to seizures.

This study was designed to (1) compare retrospective and momentary assessments of mood/affect, and (2) examine the temporal relationship between affect and seizure occurrence. Patients with epilepsy undergoing long-term video/EEG monitoring (LTM) completed an affect rating of how they felt "at that moment" each time a programmed watch beeped (momentary assessment); these ratings were averaged across each patient's hospital stay. Prior to discharge, patients were asked to think back and rate how they felt "during their hospital stay" using the same rating scale (retrospective assessment). Results indicated that patients retrospectively recalled feeling significantly more positive during their LTM than they reported feeling when they were actually undergoing LTM. Among patients who had EEG-verified seizures, momentary assessments were used to compare affect during the interictal periods with affect during the prodromal and postictal periods. The latter two periods were characterized by significantly less activated positive affect than were the interictal periods.

Episodic memory in patients with focal frontal lobe lesions.

Episodic memory was evaluated in patients with unilateral, frontal lobe damage and matched controls using a list-method directed forgetting paradigm. Directed forgetting instructions (forget vs. remember the word), encoding instructions (learn vs. judge the word) and test format (recall vs. recognition) were manipulated in order to explore how variations in encoding and retrieval affect verbal memory. Controls demonstrated a normal directed forgetting effect in recall and less directed forgetting in recognition. Patients with left frontal (LF) damage did not show directed forgetting in either recall or recognition and patients with right frontal (RF) damage showed directed forgetting in recall, but not in recognition. Furthermore, the LF group recalled significantly more of the judge than learn words, suggesting that this group's performance improves by providing them with an encoding strategy. Conversely, the RF group's performance did not depend on encoding instructions and their recognition memory was impaired relative to the other two groups when they were instructed to judge the words. Our results suggest that (a) patients with LF damage show deficits in the rehearsal of to-be-remembered information, (b) whereas patients with RF damage show impairments in recognition memory. Furthermore, both patient groups show a lack of directed forgetting when familiarity-based processes guide performance.

Attentional inhibition in patients with focal frontal lobe lesions.

Patients with unilateral, frontal lobe damage and matched controls performed an identity negative priming task as a measure of inhibition in selective attention. Control participants demonstrated a normal negative priming effect, as evidenced by slower reaction times when a previously to-be-ignored item became the target on a subsequent trial (distractor suppression). On the other hand, patients with left medial frontal lobe damage showed positive priming in the distractor suppression condition suggesting facilitation of distractor information. Patients with right frontal lobe damage showed an unreliable pattern of negative priming, some demonstrating an absence of negative priming and others demonstrating enhanced negative priming in the distractor suppression condition. Neither patient group nor controls demonstrated slower responses on a target-to-distractor condition included to evaluate a noninhibitory (i.e., episodic retrieval) account of negative priming. Taken together, our results suggest that (a) the negative priming effect represents active inhibition of a distractor representation, rather than a noninhibitory mismatch between retrieval episodes, and (b) that the frontal lobes, especially the left frontal lobes, contribute to this active inhibition.

Semantic priming in patients with right frontal lobe lesions.

Patients with unilateral, right frontal lobe damage (N=13) and matched controls (N=20) performed a task of lexical ambiguity resolution in order to explore the contribution of right frontal regions to lexical-semantic priming. Word triplets consisting of balanced homographs were presented to participants in four conditions: concordant, discordant, neutral, and unrelated. Controls demonstrated facilitation for concordant meanings of homographs, as evidenced by their faster reaction times in the concordant relative to the unrelated (baseline) condition, as well as a lack of facilitation for the discordant meaning relative to the neutral and concordant conditions. Results in patients with right frontal lobe damage differed depending on the site of the lesion. Patients with lesions restricted to the right medial frontal lobe only showed facilitation in the neutral condition, while those with lesions encroaching upon the right dorsolateral region demonstrated facilitation of both discordant and concordant meanings relative to the baseline condition. These results support a role for the right frontal lobe in semantic priming and suggest possible specialization within the right prefrontal cortex for the processing of lexical-semantic information.

Asymmetry of the hippocampus and amygdala in MRI volumetric measurements of normal adults.

Multiple studies have explored the relationship between MRI-based volumetric measurements of the hippocampus and amygdala, the degree of volumetric asymmetry of these structures, and symptom manifestation. However, considerable variability exists with regard to the reported volumetric values of these structures. The present study employed meta-analytic procedures to provide a systematic analysis of the normal population parameters of hippocampal and amygdala volumetric asymmetry as well as the absolute intrahemispheric volumes of these structures in normal adults. A literature review of studies published between 1990 and 2002 resulted in a representative sample of 82 studies (N = 3,564 participants) providing volumetric information of the hippocampus and 51 studies (N = 2,000 participants) providing volumetric information of the amygdala. Results revealed that both the hippocampus and the amygdala are reliably asymmetrical structures in normal adults, with larger right hippocampal (D = 0.21, p.001) and right amygdala (D = 0.09, p.01) volumes. Additional analyses indicated that differences in MRI magnet field strength and slice thickness values might differentially contribute to volumetric asymmetry estimates. These results expand on previous volumetric normative studies and may be relevant to investigators studying the clinical correlates of hippocampal and amygdala volumes.

Posttraumatic stress disorder, dissociation, and sexual abuse history in epileptic and nonepileptic seizure patients.

Rates of posttraumatic stress disorder (PTSD), dissociative symptoms, and childhood sexual abuse (CSA) are believed to be higher among patients with nonepileptic seizures (NES) than those with epileptic seizures (ES). However, women have higher rates of CSA and sexual assault than men. Comparisons of seizure type controlling for gender may produce different results. Data from an opportunity sample of 34 patients with ES and 17 with NES evaluated during or following phase 1 video-EEG monitoring demonstrated that patients with NES had statistically higher rates of PTSD and CSA and higher Dissociative Experiences Scale (DES) scores than patients with ES. No differences were found between women with NES and ES for histories of PTSD or CSA. Mean between-group DES score differences remained. Results indicated that PTSD, dissociation, and CSA may be common among women presenting to a tertiary epilepsy referral center for both ES and NES. Neither a positive history of CSA nor a history of PTSD was evidence against epilepsy.

Dysphagia with bilateral lesions of the insular cortex.

It has been demonstrated that the insular cortex plays an important role in the swallowing mechanism. This case report describes a patient with bilateral insular cortex lesions and dysphagia secondary to viral meningitis. Recent evaluations of the insula's role in the swallowing mechanism are discussed.

Category-specific naming deficits for objects and actions: semantic attribute and grammatical role hypotheses.

Research on category-specific naming deficits and on noun and verb naming has raised questions about how organization of knowledge in the brain impacts word retrieval. The semantic attribute hypothesis posits that lexical access is mediated by brain systems that process the most definitive attributes of specific concepts. For example, it has been suggested that the most definitive attribute of living things is their visual form, whereas the most definitive attribute of non-living things is their function. The competing grammatical role hypothesis posits that access to a word depends on the grammatical role it plays in a sentence. Since nouns and verbs have different roles, it is assumed that the brain uses different systems to process them. These two hypotheses were tested in experimental subjects who had undergone left anterior temporal lobectomy (LATL) or right anterior temporal lobectomy (RATL) by assessing confrontation naming of living things, tools/implements, non-human actions, and human actions. The names of living things and implements are nouns and the names of actions are verbs. Within each grammatical class, items were characterized either predominantly by visual attributes (living things and non-human actions) or by attributes related to human activity (implements and human actions). Our results support the semantic attribute hypothesis. Patients with LATL were worse at naming tools/implements and human actions than RATL patients. Dysfunction in or removal of the left anterior temporal lobe disrupts fronto-temporal connections from the uncinate fasciculus. These connections may mediate activation of action-related information (i.e. movement plan and/or motor use) that facilitates the retrieval of names for tools/implements and human actions.

Progressive dementia and hypersomnolence with dream-enacting behavior: oneiric dementia.

BACKGROUND: Sleep disorders are associated with several types of degenerative dementias, including Alzheimer and prion diseases. Animal models have demonstrated abolition of rapid eye movement atonia, resulting in dream-enacting complex movements termed oneiric behavior, and patients with fatal familial insomnia may have vivid dreams that intrude on wakefulness. OBJECTIVE: To describe a new form of progressive dementia with hypersomnia and oneiric behavior. METHODS: Neuropsychological and polysomnographic studies of a middle-aged woman with a progressive dementia, excessive daytime sleepiness, and a vertical gaze palsy. RESULTS: Neuropsychological testing revealed decreased verbal fluency, impaired attention and working memory, amnesia, poor recall, and bradyphrenia with hypersomnia. Polysomnography revealed a rapid eye movement behavioral disorder with complete absence of slow wave sleep. Prion protein analysis did not reveal the mutation associated with fatal familial insomnia, and other diagnostic test findings were unrevealing. CONCLUSION: Our patient had a previously unreported syndrome of progressive dementia associated with rapid eye movement behavioral disorder and the absence of slow wave sleep.