A prospective study of electrophysiological and behavioural measures of cognitive function in patients with epilepsy

PhDAims: The aim of this thesis was firstly, to prospectively examine cognitive function in relation to epilepsy, with event-related potential (ERP) and neuropsychological assessments, over a one year period. Secondly, to investigate whether electrophysiological measures have some predictive value for behavioural outcomes. Methods: A methodology development study investigated optimal stimulus and recording parameters for the mismatch negativity (MMN). A prospective epilepsy study included investigation of a healthy control group, groups of patients with: primary generalised seizures (PGS), focal with secondary generalised seizures (FSG) or focal seizures (FS) and a chronic pain group undergoing anti-epileptic drug (AED) therapy. Assessments were conducted over the course of 12 months: at baseline (session 1), 6-months follow-up (session 2) and 12- months follow-up (session 3). ERP measures included the MMN, P3b and P3a. Neuropsychology measures were obtained using visual reaction time, spatial working memory, planning, word list learning, perseverative function, story recall memory and word list learning tests. Cross-sectional analyses of data obtained at sessions 1 and 2 were carried out to investigate group differences at the different time points. Longitudinal analyses were carried out to investigate the effect of time on behavioural and ERP changes in relation to the different groups. Finally, the predictive value of baseline ERPs for behavioural outcomes at one year follow-up was explored. Results: The methodology development study demonstrated that a reading task with duration increment tones yielded the most replicable MMNs in healthy controls. The clinical study demonstrated significant changes in some ERP components obtained from standard oddball, dual target oddball and novel sounds tasks, between controls and seizure groups -some of which were only apparent at session 3. Although the seizure groups showed evidence of significant impairments in aspects of behavioural performance, there was no significant progressive deterioration over time. Moreover, although the pain group showed similar behavioural impairments, in contrast to the seizure groups, they showed significant improvements in some aspects of performance over time. Conclusion: An MMN recording protocol was established for use with the subsequent prospective clinical study. The prospective epilepsy study revealed functional cognitive changes that may be linked to the nature of pathophysiology underlying different seizure types

A Clinical Electrophysiological Study of Emotional Lability in Patients With Systemic Lupus Erythematosus

Neuropsychiatric symptoms are well recognized in systemic lupus erythematosus (SLE), with depression and anxiety often reported. The authors’ clinical observations suggested emotional lability might also be a noteworthy symptom. In a consecutive series of systemic lupus erythematosus clinic attendees, the authors, therefore, measured depression, anxiety, and emotional lability. Additionally, based on reports linking emotional reactivity and transient mood changes to alterations in early attentional processes, the authors investigated event-related potential indices of preattentive and early orienting responses to auditory stimuli (N1, MMN, P3a and P3b). The authors observed that 15 of 32 participants with systemic lupus erythematosus had high lability scores and, comparing event-related potential measures between the high and low lability subgroups, noted that those with greater emotional lability demonstrated reduced response latencies in N1 and MMN paradigms

Evaluation of absences and myoclonic seizures in adults with genetic (idiopathic) generalized epilepsy:a comparison between self-evaluation and objective evaluation based on home video-EEG telemetry

Objective. People with focal epilepsies are known to under-document their seizures, but there is no data on self-documentation in adults with genetic (idiopathic) generalized epilepsy (GGE/IGE). We assessed the accuracy of self evaluation of typical absences (TA) or myoclonic seizures (MS) in adults with IGE based on home video-EEG telemetry (HVET). Methods. Patients' own estimates were compared to the objective count of definite TA and MS, performed visually. We considered definite TA as generalized spike-wave discharges (GSWD) that met any of the following criteria: 1) coinciding with clear behavioural arrest on video, 2) followed after a few seconds by positive indication that an absence occurred, or 3) in the absence of video, consistently coinciding with clear motor arrest, as evidenced by interruption of continuous muscle activity. For each patient, we also classified probable TA as GSWDs that were longer than those corresponding to the shortest definite TA on HVET or based on the most recent sleep-deprived EEG (SDEEG). Results. From the first 300 consecutive adults who had HVET, 24 had IGE with TA and / or MS; 23 were women. Only one patient had newly diagnosed IGE. Erroneous self-assessment of TA and MS was noted in 16/24 patients (66.7%). Seizures were overestimated in nine (37.5%) and underestimated in seven (29.2%). Only one patient (4.2%) documented all her TA and MS without false positive estimates. Overestimation (but not underestimation) of TA on HVET could be predicted when patients reported daily or multiple weekly TA and a recent SDEEG was either normal or contained only subclinical GSWD (p=0.0095). Significance. Under-and over-self-documentation of TA and MS occurred in two thirds of adults with GGE/IGE, with substantial impact on their outpatient management and treatment. Diagnostic HVET is a useful tool for the detection of erroneous self-evaluation in these patients