P300 abnormalities in patients with selective impairment of recent memory

Auditory Temporal Ordering in Patients with Medial Temporal Lobe Epilepsy with and without Hippocampal Sclerosis

Context

Temporal lobe epilepsy can affect central auditory processing (CAP) skills. Auditory temporal ordering (ATO) is a CAP skill that can be evaluated using duration pattern test (DPT).

Aim

The aim is to evaluate ATO in patients with medial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (MTLE + HS) and without hippocampal sclerosis (MTLE-HS) and in their subgroups.

Settings and Design

It was a prospective cross-sectional behavioral observational study conducted in a tertiary neuropsychiatric hospital.

Subjects and Methods

The subjects were patients with refractory MTLE (N = 100), comprising 50 "MTLE + HS" patients and 50 "MTLE-HS". Age-range matched normal healthy subjects (n = 50) formed the control group. Both groups were administered duration pattern test (DPT).

Statistical Analysis Used

Analysis of variance (ANOVA) with post hoc analysis, Dunnett's two-sided and Bonferroni, paired sample t-test, Pearson's correlation, and independent t-test.

Results

The clinical groups performed significantly poorer than the control group, and however, did not differ significantly between them. The age at onset and the duration of the seizures did not have significant relation with the test measures.

Conclusions

Patients with "MTLE + HS" as well as those with "MTLE-HS" and their respective subgroups revealed abnormal ATO indicating CAP dysfunction.

Investigation of auditory potentials and cognitive impairment in premenstrual syndrome

Premenstrual syndrome is a term which is used for describing of somatic, cognitive, emotional, and behavioral symptoms that occur during the luteal phase of menstrual cycle in women of reproductive age; symptoms rapidly improve at the onset of menstruation. In this study, we aimed to reveal if cognitive functions are affected or not in PMS and if the subjects are affected, we try to explain this situation by an objective diagnostic test. Ethical committee approval was taken for this project on 09.03.2012 and numbered 050.99-60. In this study, in order to determine premenstrual syndrome, "Premenstrual Syndrome Scale" that is developed by Gençdoğan (2006) with 44 items, Likert type, and 9 subgroups was used. Sample size was calculated using simple random sampling with a confidence level of 95% and confidence interval of 0.05. A total of 60 participants were included in the study (calculated sample size was 30 for each group). Each group was recorded in the ENMG-UP laboratory using the OIP auditory warning and the "oddball two-tone discrimination task" method. Latency measurements were taken from the highest point of the peak, and amplitude measurements were taken from peak to peak with a cursor. Comparisons of P300 wave latencies obtained via sparse auditory stimulus in PMS and non-PMS groups were made and findings were summarized in one of the tables. Recordings are taken from three scalp regions: parietal and central, respectively. PMS women have longer P300 wave latencies in all regions compared to non-PMS group, whereas there is no significant difference between P300 amplitude.

Cognitive processing of cluster headache patients: evidence from event-related potentials

BACKGROUND

The peripheral and central origins of pain in cluster headache (CH) have been a matter of much debate. The development and application of functional imaging techniques have provided more evidence supporting the hypothesis that CH is not a disorder exclusively peripheral in origin, and in fact central regions might be more important. Event-related potentials confer advantages in the functional evaluation of the cortex, but few studies thus far have employed this method in cluster headache.

METHODS

Seventeen cluster patients (15 males; mean age = 35.4 years) and 15 age-matched healthy participants (13 males; mean age = 34.6 years) were recruited. A visual oddball paradigm was employed to analyze target processing using event-related potentials. We investigated the P3/P3d components in the experiment.

RESULTS

P3/P3d amplitudes were decreased in CH patients (P3, 3.82 μV; P3d, 5.8 μV) compared with controls (P3, 7.28 μV; P3d, 8.95 μV), F(1,30) = 4.919, p < 0.05, η2 = 0.141 for P3 and F(1,30) = 8.514, p < 0.05, η2 = 0.221 for P3d, respectively). Moreover, the amplitudes of P3/P3d were no significantl difference in the side of pain as compared to contralateral one (p > 0.05).

CONCLUSIONS

These results provide evidence of dysfunction in the cognitive processing of CH patients, which may also contribute to the pathophysiology of CH.

Event related potentials in patients with transient global amnesia--a prospective controlled study

OBJECTIVE

The aim of this study is to evaluate changes in the latencies and amplitudes of event-related potential (ERP) components as well as cognitive habituation in patients with transient global amnesia (TGA) in order to further characterize the pathology of this syndrome.

METHODS

Clinical data of 43 consecutive patients with TGA was collected at a university neurology department. Follow-up examination was performed at an average of 17months after TGA. Results were compared to 43 age- and sex-matched healthy control subjects.

RESULTS

All ERP latencies of patients examined within 10days after the TGA period were significantly increased, and the P3 amplitude was significantly decreased as compared to healthy control subjects. The rate of pathological P3 latencies was significantly higher in TGA patients. A normal P3 latency habituation was detected in 84% of all healthy controls (mean habituation 10ms) and in 33% of all TGA patients (mean habituation -6ms). There was no significant improvement of all latencies and the other ERP parameters, including the loss of habituation, after a mean observation period of 17months. The data of three patients who were measured during the TGA period suggest a severe impairment of ERP during this period.

CONCLUSIONS

Our findings give new insight into the pathology of TGA and put into question if TGA is an event of a simple transient character. In this first investigation of cognitive habituation in patients with TGA, we found a characteristic loss of cognitive habituation similar to observations in migraine.

From amnesia to dementia: ERP studies of memory and language

Cognitive event-related potential (ERP) studies of memory and language impairments in amnesia and Alzheimer's disease (AD) are reviewed. Well-circumscribed lesions of the medial temporal lobe (MTL) or diencephalon causing an amnestic syndrome, an inability to encode and retrieve episodic memories beyond the brief duration of working memory, appear to produce altered plasticity of the late positive P600 component, but usually spare P300 and N400 components. The neuropathology of AD affects MTL and extends to neocortical association areas, causing deficits of episodic and semantic memory. In AD dementia, the P300, N400, and P600 all commonly show abnormalities. ERP studies of individuals with mild cognitive impairment may reveal neurophysiological changes prior to the emergence of clinical deficits, which could advance the early detection and diagnosis of AD.

Cognitive processing in cluster headache

Little is known about specific changes of cognitive processing in cluster headache. Studies on event-related potentials (ERP) suggest that stimulus evaluation is impaired in chronic cluster headache and in episodic cluster headache during the cluster period, but not in the interval between two periods. Patients with chronic paroxysmal hemicrania do not show this impairment. Unlike patients with migraine, patients with cluster headache do not present with a loss of cognitive habituation as measured by ERP. In neuropsychologic evaluations, a reversible decline of memory processing was detected during the cluster attack, but not between two attacks. Long-term observation revealed no progressive cognitive decline in cluster headache patients over the years. With regard to personality changes, a liability susceptibility to anxiety disorders and to hypochondriasis, but not to mood changes, has been described inconsistently. All changes in alterations of cognitive processing in cluster headache are demonstrated to be mild and do not relevantly contribute to the clinical picture of this disease.