Nonadherence to treatment causing acute hospitalizations in people with epilepsy: An observational,prospective study

The aim was to assess the clinical relevance of antiepileptic drug (AED) nonadherence by means of therapeutic drug concentration monitoring (TDM). Two hundred eighty‐two consecutive patients with epilepsy acutely admitted to hospital for seizures were included. Nonadherence was defined as having a serum concentration/dose ratio at admission of <75% of the patient's own control value (probable nonadherence: 50–75%; definite: <50%). Nonadherence was identified in 39% of patients (definite 24%; probable 15%). It was significantly more common in patients with generalized seizures compared to those with focal onset seizures, and in patients <30 years compared to older patients. When specifically asked, 44% of nonadherent patients claimed regular intake. Nonadherence is a major cause of seizure breakthrough in patients with epilepsy, particularly in young adults. Many patients seem to be unaware of missed drug intake. Prompt measurements of AED serum concentrations should be available as part of the emergency care for patients acutely hospitalized for seizures to permit this issue to be thoroughly addressed prior to discharge.     

Frequency–moment signatures: A method for automated seizure detection from scalp EEG

Objectives

To investigate patient-specific automated epileptic seizure detection from scalp EEG using a new technique: frequency–moment signatures.

Methods

Signatures were calculated from 32 s blocks of data of electrode differences from the right (RH) and left hemisphere (LH). Discrete Fourier transforms of 15 data subsets were calculated per block per hemisphere. The spectral powers at a given frequency from the RH and LH were combined into a single quantity. The signature elements were found by subtracting normalised central moments of the subset distribution from the mean, to measure the consistency of the spectral power at a given frequency over all subsets. The seizure measure was the logarithm of the probability that a signature belonged to a control set of non-seizure signatures.

Results

Following the optimisation of signature parameters using three one-day recordings from each of 12 patients, performance was tested on a separate set of data from the same patients. The method had a sensitivity of 91.0% (total 34 seizures) with 0.020 false positives per hour (total 618 h).

Conclusions

Frequency–moment signatures promise automated seizure detection sensitivities comparable to visual identification and other published methods, with improved false detection rates.

Significance

This technique has the potential to be used more widely in EEG analysis.     

Differential Impact of Executive Function on Visual Memory Tasks

Despite their common use in neuropsychological evaluation, little is known about the differential contribution of executive functioning to visual memory tests. In this study, hierarchical regression was used to determine the role of executive functioning on the Visual Reproduction subtest of the Wechsler Memory Scale—Third Edition, and the Rey-Osterrieth Complex Figure (ROCF) in a mixed neurological sample of 193 patients. Executive functioning was predictive of Visual Reproduction but not ROCF recall variables after accounting for demographic variables and global cognitive functioning. Only executive tests with a visuospatial component, the Trail-Making Test Part B and Wisconsin Card Sorting Test perseverative responses, were predictive of recall of Visual Reproduction stimuli. Organization of the ROCF was predictive of both Visual Reproduction and ROCF recall. These findings increase our understanding of the executive contribution to two common visual memory tests and may aid in the clinical interpretation of seemingly discrepant visual memory performance.     

Seizure recurrence and remission after switching antiepileptic drugs

Purpose: Studies of seizure outcome in patients undergoing serial antiepileptic drug trials have all been uncontrolled, with no account made for the spontaneous changes in disease state that could confound the elucidation of drug effects. In addition, no study has ever looked at outcome following antiepileptic drug switch in seizure‐free patients, despite the fact that this is done routinely in clinical practice. We aimed to address both of these issues using a matched case‐cohort design. Methods: We followed patients taking phenytoin or carbamazepine in monotherapy for focal epilepsy who were being crossed over to a newer agent as part of studies on the metabolic effects of anticonvulsant therapy. Many had been seizure‐free but were being switched nonetheless due to side effects or concerns about long‐term adverse consequences. Each patient was matched with two controls of the same seizure status who were taking anticonvulsant monotherapy and whose drug was not switched. Seizure freedom over the ensuing 6 months was the primary end point. Key Findings: There were 43 cases and 86 matched controls. Twenty‐three patients (cases) had been seizure‐free on their old drug; 5 (21.7%) had seizure recurrence after drug switch compared to 2 (4.3%) of 46 matched controls. Twenty patients (cases) were having seizures on their old drug; 6 (30%) entered remission after drug switch, compared to 8 of 40 matched controls (20%). The two groups differed at baseline in number of anticonvulsants previously failed, which was the most important factor for prognosis. After statistical adjustment to account for this, seizure‐free patients had 6.53 times higher odds of seizure recurrence if switched to a new drug (95% confidence interval [CI] 1.02–61.19; p = 0.06). Non–seizure‐free patients had 1.66 times higher odds of remission if they remained on the same drug compared to switching, although this was not significant (95% CI 0.36–8.42; p = 0.532). Neither dose changes, nor drug mechanism, nor duration of seizure freedom had any bearing upon the results. Significance: Although the large majority of seizure‐free patients remain so when switched to another agent, about one sixth have a recurrence attributable to the change. Conversely, our study design provides the first evidence to suggest that most improvements in drug‐resistant patients are likely due to spontaneous remissions, not new drug introductions. These findings have conflicting implications for two competing models of comparative antiepileptic drug efficacy, which will require further study to elaborate.