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Biomedical subjects

Donald L Schomer

Publications and source records attributed to Donald L Schomer.

At least 19 recordsLinked to original sources
PubMed2006

Behavioral, social, and affective factors associated with self-efficacy for self-management among people with epilepsy.

The purpose of the study described in this article was to evaluate the extent to which selected behavioral, social, and affective factors contribute to self-reported epilepsy self-efficacy. Participants completed three assessments 3 months apart, with only those completing both the first and second assessments included in this analysis. Self-efficacy scores at the second assessment were regressed on the behavioral, social, and affective characteristics ascertained at the first assessment. The analysis revealed that self-management, depressive symptoms, and seizure severity explain the most variance in self-efficacy; patient satisfaction and stigma are less important predictors; and social support and regimen-specific support are not significant predictors. The results provide direction for identifying people with low levels of self-efficacy and highlighting areas that might help enhance self-efficacy in persons with epilepsy.

Adult↗
PubMed2006

Processing stages underlying word recognition in the anteroventral temporal lobe.

The anteroventral temporal lobe integrates visual, lexical, semantic and mnestic aspects of word processing, through its reciprocal connections with the ventral visual stream, language areas, and the hippocampal formation. We used linear microelectrode arrays to probe population synaptic currents and neuronal firing in different cortical layers of the anteroventral temporal lobe, during semantic judgments with implicit priming and overt word recognition. Since different extrinsic and associative inputs preferentially target different cortical layers, this method can help reveal the sequence and nature of local processing stages at a higher resolution than was previously possible. The initial response in inferotemporal and perirhinal cortices is a brief current sink beginning at approximately 120 ms and peaking at approximately 170 ms. Localization of this initial sink to middle layers suggests that it represents feedforward input from lower visual areas, and simultaneously increased firing implies that it represents excitatory synaptic currents. Until approximately 800 ms, the main focus of transmembrane current sinks alternates between middle and superficial layers, with the superficial focus becoming increasingly dominant after approximately 550 ms. Since superficial layers are the target of local and feedback associative inputs, this suggests an alternation in predominant synaptic input between feedforward and feedback modes. Word repetition does not affect the initial perirhinal and inferotemporal middle layer sink but does decrease later activity. Entorhinal activity begins later (approximately 200 ms), with greater apparent excitatory post-synaptic currents and multiunit activity in neocortically projecting than hippocampal-projecting layers. In contrast to perirhinal and entorhinal responses, entorhinal responses are larger to repeated words during memory retrieval. These results identify a sequence of physiological activation, beginning with a sharp activation from lower level visual areas carrying specific information to middle layers. This is followed by feedback and associative interactions involving upper cortical layers, which are abbreviated to repeated words. Following bottom-up and associative stages, top-down recollective processes may be driven by entorhinal cortex. Word processing involves a systematic sequence of fast feedforward information transfer from visual areas to anteroventral temporal cortex followed by prolonged interactions of this feedforward information with local associations and feedback mnestic information from the medial temporal lobe.

Adult↗
PubMed2006

Ambulatory EEG telemetry: how good is it?

When someone asks the question, how good is ambulatory EEG telemetry, there is no correct answer. There are many manufacturers of ambulatory EEG technology. Each device has its own strengths and weaknesses. What one is really interested in when one asks such a question needs to be defined in terms of expectations and technical capabilities for the piece of equipment under discussion. Systems exist or can be easily modified to be as sophisticated as the best of the inpatient units. However, is that level of sophistication needed for the ambulatory based recordings? Again, the answer to that is dependent on the ordering physician's expectations. Below is a discussion of the different clinical expectations that are frequently encountered and the needed requirements for an ambulatory system to properly address them.

Diagnosis, Computer-Assisted↗
PubMed2006

Differential effects of antiepileptic drugs on neuroactive steroids in men with epilepsy.

PURPOSE: To compare serum levels of neuroactive steroids among men with epilepsy who take various antiepileptic drugs, untreated men with epilepsy and normal controls (NC). METHODS: Subjects were 85 men with localization-related epilepsy [unmedicated >6 months (No Rx)-10, carbamazepine (CBZ)-25, phenytoin (PHT)-25, lamotrigine (LTG)-25] and 25 NC. Sexual function scores (S-Score), hormone levels [dehydroepiandrosterone sulfate (DHEAS), bioactive (BA) testosterone (T), estradiol (BAE), and androstanediol (BAL)] and the ratios of inhibitory to excitatory neuroactive metabolites of T, i.e., BAL/BAE, were compared among groups. RESULTS: S-scores, DHEAS, and bioactive testosterone (BAT) were significantly (p < 0.05) lower and BAL and BAL/BAE were significantly higher among CBZ and PHT groups than among NC and LTG groups. LTG did not differ from NC in any of these measures. BAT correlated significantly with BAL/BAE for PHT (r = 0.44, p = 0.02) and CBZ (r = 0.42, p = 0.03) but not for NC (r = 0.03, p = NS) and LTG (r = 0.06, p = NS) groups. CONCLUSIONS: In comparison to LTG, enzyme inducing AEDs (CBZ, PHT) are associated with a more favorable neuroactive steroid balance (lower DHEAS and higher BAL/BAE) for seizure management, but at the expense of reduced serum bioavailable testosterone levels and sexual function.

Adolescent↗
PubMed2005

The complexity of treatments for persons with epilepsy.

The purpose of this study was to describe the types of antiepileptic medication regimens and the types of actions required to take medications for a group of patients with epilepsy. The Epilepsy Medication and Treatment Complexity Index (EMTCI) was used to gather information about medications and treatments. The sample of 314 reported on 585 epilepsy medications. The majority (56%) were on more than one treatment. On average, an individual took 1.86 medications per day (range, 1-6) and 7.98 pills per day (range, 1-36 pills). Most medications (54%) were taken twice a day. The most common special instruction was taking different doses on the same day. Taking more than one tablet per dose was the most common administrative action. Data presented here raise interesting areas for further research as well as important clinical implications.

Adult↗
PubMed2005

Responses of human anterior cingulate cortex microdomains to error detection, conflict monitoring, stimulus-response mapping, familiarity, and orienting.

Human anterior cingulate cortex (ACC) activity modulation has been observed in numerous tasks, consistent with a wide variety of functions. However, previous recordings have not had sufficient spatial resolution to determine whether microdomains (approximately one to two columns) are involved in multiple tasks, how activity is distributed across cortical layers, or indeed whether modulation reflected neuronal excitation, inhibition, or both. In this study, linear arrays of 24 microelectrodes were used to estimate population synaptic currents and neuronal firing in different layers of ACC during simple/choice reaction time, delayed word recognition, rhyming, auditory oddball, and cued conditional letter-discrimination tasks. Responses to all tasks, with differential responses to errors, familiarity, difficulty, and orienting, were recorded in single microdomains. The strongest responses occurred approximately 300-800 ms after stimulus onset and were usually a current source with inhibited firing, strongly suggesting active inhibition in superficial layers during the behavioral response period. This was usually followed by a sink from approximately 800 to 1400 ms, consistent with postresponse rebound activation. Transient phase locking of task-related theta activity in superficial cingulate layers suggested extended interactions with medial and lateral frontal and temporal sites. These data suggest that each anterior cingulate microdomain participates in a multilobar cortical network after behavioral responses in a variety of tasks.

Acoustic Stimulation↗
PubMed2004

Frequency of catamenial seizure exacerbation in women with localization-related epilepsy.

This investigation assessed the frequency of catamenial epilepsy in 87 women who charted seizures and menses during three cycles. Catamenial epilepsy designation was made if two of three cycles showed at least one of three previously defined catamenial patterns. Among ovulatory cycles, average daily seizure frequency was significantly greater during the perimenstrual and preovulatory phases. Among anovulatory cycles, average daily seizure frequency was substantially less during the midfollicular phase than during the remainder of the cycle. Overall, 39.1% of the women had catamenial epilepsy.

Adolescent↗
PubMed2004

Differential effects of antiepileptic drugs on sexual function and reproductive hormones in men with epilepsy: interim analysis of a comparison between lamotrigine and enzyme-inducing antiepileptic drugs.

PURPOSE: We compared sexual function and reproductive hormone levels among men with localization-related epilepsy (LRE) taking various antiepileptic drugs (AEDs) and normal controls (NC). METHODS: Subjects were 63 men with LRE [enzyme-inducing (EI) AEDs, 36; lamotrigine (LTG), 18; no AEDs, 9] and 18 NC. Sexual interest and function (S-score), hormone levels [bioactive testosterone (BAT) and estradiol (BAE)], hormone ratios [BAT/BAE], and gonadal efficiency [BAT/luteinizing hormone (LH)] were compared among the groups. RESULTS: S-scores, BAT levels, BAT/BAE, and BAT/LH were significantly lower in the EIAED group than in NC or LTG groups. Sex hormone-binding globulin (SHBG) was significantly higher in the EIAED group than in all other groups. Of men with LRE, 23.8% had abnormally low S-scores: 33.3% taking EIAEDs, 5.5% taking LTG, and 22.2% taking no AEDs (p < 0.01). BAT was low in 55.6% taking EIAEDs as compared with 33.3% taking LTG and 33.3% taking no AEDs (p < 0.05). Among men with low S-scores, 86.7% had low BAT as compared with 33.3% of men with normal scores (p < 0.01). BAT decline with age was greater among men with LRE than in controls (3.75 vs. 1.80 ng/dl/yr). The slope showed no significant difference among LRE groups. However, 89% of 40- to 50-year-old men taking EIAEDs had low BAT as compared with 33% taking LTG and 33% taking no AED (p < 0.01). CONCLUSIONS: Sexual function, BAT levels, BAT/BAE, and gonadal efficiency are greater with LTG than with EIAED. Abnormally low BAT levels are reached at an earlier age with EIAEDs than with LTG.

Adolescent↗
PubMed2003

Interictal EEG discharges, reproductive hormones, and menstrual disorders in epilepsy.

We evaluated reproductive endocrine function in women with unilateral temporolimbic epilepsy and normal control subjects to assess the effects of epilepsy, epilepsy laterality, and antiepileptic drug use on the cerebral regulation of hormonal secretion. The findings indicate that reproductive endocrine function differs between women with epilepsy and normal control subjects. Significant differences exist at all levels of the reproductive neuroendocrine axis, that is, hypothalamus, pituitary, and peripheral gland. Differences show significant relationships to the epilepsy itself as well as to medication use. Reproductive neuroendocrine changes occur in a stochastic manner such that the laterality of unilateral temporolimbic discharges is associated with predictable directional changes in hormonal secretion at all levels of the reproductive neuroendocrine axis. These directional changes are consistent with the finding that different reproductive disorders may develop in relation to left- and right-sided temporolimbic epilepsy. Hormonal changes can show close temporal relationship to the occurrence of interictal epileptiform discharges and may vary in relation to the laterality of the discharges. Antiepileptic drugs differ in their effects on reproductive hormone levels. There are notable differences between enzyme-inducing and noninducing drugs. Menstrual disorders are more common among women with interictal discharges as well as women with abnormal hormonal findings.

Adolescent↗
PubMed2003

Further standardization of some NES3 tests.

NES3 is a computer-based neurobehavioral testing system designed for use in investigating potential cognitive impairment. Data from NES3 tests employed in a study of epilepsy self-management were analyzed to estimate test-retest reliability for NES3 tests on a large sample and to estimate the effect of some common covariates of test performance. A total of 319 participants in an epilepsy self-management study were examined on three occasions (baseline, 3-month follow-up, and 6-month follow-up) with a set of psychological questionnaires and seven neuropsychological tests from NES3. Test-retest correlations were calculated between measures obtained at baseline and at 3 months. Principal components analysis was performed on the baseline data. The potential effects of covariates (age, education, reading test scores, depression status, and examiner) were investigated in regression models. Three-month test-retest correlations were excellent for Adult Reading Test (ART) (r=0.95), strong for Digit-Symbol (r=0.82), Sequence B (r=0.79), and Sequence A (r=0.76); and modest (r's between 0.56 and 0.67) for Digit Span Forward and Backward, Visual Span Forward and Backward, and Pattern Memory. Alternate-forms correlations were strong for HVLT (r's between 0.71 and 0.82). Principal components analysis yielded four interpretable components. Age and reading score were significant covariates of virtually all of the test summary measures, while education, gender, race, and depression were not generally significant covariates. Changes to the method of calculation of some summary measures, changes to the initial instructions to the subjects, and addition of correctional feedback to subjects during the tests appeared to improve the reliability of some NES3 tests. Implementation of the HVLT and ART in computer-assisted format added breadth of coverage to the battery. NES3 tests may provide reliable, efficient data for use in epidemiologic studies of potential cognitive effects of occupational and environmental exposures.

Adolescent↗
PubMed2003

A computer-based reading test for use as an index of premorbid general intellectual level in North American English-speaking adults.

Brief tests of vocabulary or reading ability are often used as an index of general intellectual level to hypothesize deficits in patients, to establish comparability of comparison groups, and as a covariate of performance on other neuropsychological tests. We evaluated a new variant of a reading test for potential use in estimating premorbid general intellectual ability and implementation as a computerized-adaptive test. A total of 319 outpatients who participated in an epilepsy self-management study were tested on three occasions, completing the Wide-Range Achievement Test-3 (WRAT-3) Reading test at baseline and the NES3 Adult Reading Test (ART) at the 3-month follow-up. At the 6-month follow-up, some participants completed the ART and some the NES2 Vocabulary test. ART and WRAT-3 Reading scores obtained 3 months apart were highly correlated (r=0.87, n=179), while ART and NES2 Vocabulary scores were somewhat less correlated (r=0.80, n=61). The ART test-retest correlation was high (r=0.95, n=79). The ART distribution was spread out more evenly at the high end than that of the WRAT-3 Reading. ART score was significantly related to education, race, income, and examiner category, but was unrelated to age category and depression status. Non-significant gender differences were observed. An item-response theory (Rasch model) analysis showed good fit of the model to the observed data and yielded an improved ranking of the ART items in order of difficulty. The NES3 ART exhibited high reliability and strong association with WRAT-3 Reading. These results suggest that the NES3-ART may be useful as an index of general intellectual ability for comparison of groups and for use as a covariate in data analyses among English-speaking, North American adults. The Rasch model analysis provides a basis for implementing the ART as a computerized-adaptive test, which should improve its time efficiency and reduce participant burden in taking the test.

Adolescent↗
PubMed2003

The association of stigma with self-management and perceptions of health care among adults with epilepsy.

OBJECTIVE: The purpose of this study was to examine the perception of stigma among adults with epilepsy including its association with epilepsy self-management and perceptions of health care. METHODS: Participants for the study were recruited from two epilepsy centers and a neurology clinic. Individuals agreeing to participate in the study were asked to complete three assessments each 3 months apart. Data were collected from 320 adult men and women with epilepsy; 314 provided responses on stigma and were included in this analysis. RESULTS: Participants ranged in age from 19 to 75 years (mean=43). Fifty percent of the sample was female, and 80% was white. The mean age of seizure onset was 22 years, and 76% of participants reported having had a seizure within the past year. Analysis suggests levels of perceived stigma are similar for men and women and across ethnic and age groups. However, participants who were not married or living with a partner, were not working for pay, and had limited income reported higher levels of stigma than did married participants, those working for pay, and those in higher income brackets. Participants reporting higher levels of stigma included those who had their first seizure before the age of 50 and a seizure in the last year. Participants whose seizures interfered more with activities, who rated their seizures as under less control, and who were not legally able to drive also reported higher levels of stigma. Tests of association between stigma and health-related variables revealed that participants reporting higher levels of perceived stigma also reported lower levels of self-efficacy to manage epilepsy; more negative outcome expectancies related to treatment and seizures; and lower levels of medication management, medication adherence, and patient satisfaction. However, they also reported greater management of information related to seizures. In regression analysis, income, age at first seizure, seizures during the past year, lower self-efficacy, negative outcome expectancies for seizures, and less patient satisfaction explained 54% of the variance in perceived stigma. CONCLUSIONS: The results of the study suggest that perceived stigma is significant for people with epilepsy and is associated with factors that are known to be important in the management of epilepsy. Understanding who is at greatest risk for feeling stigmatized could lead to the development of preventive measures.

Adolescent↗
PubMed2003

Relationship of sexual dysfunction to epilepsy laterality and reproductive hormone levels in women.

Sexual dysfunction has been reported to be common among women with epilepsy. Controlled studies, quantitative data, and investigations of potentially contributory factors, however, have been few. The purpose of this investigation was to determine if (1) sexual dysfunction is unusually common among women with partial seizures of temporal lobe origin (TLE), and (2) sexual dysfunction varies in relation to the laterality of EEG epileptiform discharges, antiepileptic drug use, and serum gonadal steroid levels. This controlled prospective investigation used a quantitative sexual rating scale and reproductive hormone measures to compare sexual dysfunction in women with left and right unilateral temporolimbic epilepsy and controls. Sexual dysfunction scores were significantly higher in women with TLE, and sexual dysfunction affected substantially more women with epilepsy than controls. Women with right-sided foci were affected more than women with left-sided foci. There was a significant inverse correlation between sexual dysfunction and bioactive testosterone levels in women with epilepsy as well as in controls. Serum estradiol was lower in women with TLE but did not correlate significantly with overall sexual dysfunction. The findings suggest that sexual dysfunction is significantly more common in women with right-sided epileptiform discharges than in controls and is inversely correlated with bioactive testosterone levels. The value of hormonal replacement or supplementation remains to be explored.

Adolescent↗
PubMed2003

The epilepsy medication and treatment complexity index: reliability and validity testing.

Medications are the most common treatment for epilepsy. Regimens vary from once per day dosing to several pills several times per day. More complex regimens have been associated with lower adherence rates. To date, medication complexity has been measured by the number of pills and the number of times per day the pills are taken. However, complexity also includes special instructions (e.g., take at a separate time than other medications) and the specific administration actions (e.g., take 1/2 pill). This article describes the development of an instrument designed to measure the complexity associated with epilepsy treatment regimens. The medication complexity tool (MCI) was modified to create the Epilepsy Medication and Treatment Complexity Index (EMTCI). The EMTCI comprises four sections: (a) general medication information, (b) frequency of administration, (c) special instructions, and (d) administration actions. Points are given for dosing schedules, special instructions, and administration actions. A total complexity score is calculated by adding points for each section. One form is completed for each medication prescribed for each person. The initial development of the EMTCI included revising the MCI to make it applicable to epilepsy medication. Interrater and intrarater reliability assessments were conducted. The EMTCI was administered to adults with epilepsy as part of a larger study of self-management in people with epilepsy. Data from that study were used for further assessments of the EMTCI including test-retest reliability, criterion validity, and construct validity. The EMTCI shows evidence of both reliability and validity. Information from the tool can be used to describe the medication complexity of epilepsy medication regimens in much greater detail than has been done previously for this population. This information is useful in describing the treatment and adherence issues for persons with epilepsy.

Adult↗
PubMed2002

Aspartame: review of safety.

Over 20 years have elapsed since aspartame was approved by regulatory agencies as a sweetener and flavor enhancer. The safety of aspartame and its metabolic constituents was established through extensive toxicology studies in laboratory animals, using much greater doses than people could possibly consume. Its safety was further confirmed through studies in several human subpopulations, including healthy infants, children, adolescents, and adults; obese individuals; diabetics; lactating women; and individuals heterozygous (PKUH) for the genetic disease phenylketonuria (PKU) who have a decreased ability to metabolize the essential amino acid, phenylalanine. Several scientific issues continued to be raised after approval, largely as a concern for theoretical toxicity from its metabolic components--the amino acids, aspartate and phenylalanine, and methanol--even though dietary exposure to these components is much greater than from aspartame. Nonetheless, additional research, including evaluations of possible associations between aspartame and headaches, seizures, behavior, cognition, and mood as well as allergic-type reactions and use by potentially sensitive subpopulations, has continued after approval. These findings are reviewed here. The safety testing of aspartame has gone well beyond that required to evaluate the safety of a food additive. When all the research on aspartame, including evaluations in both the premarketing and postmarketing periods, is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.

Affect↗