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Vincent P Mathews

Publications and source records attributed to Vincent P Mathews.

13 recordsLinked to original sources
PubMed2006

Magnetic resonance imaging (MRI) and electroencephalographic (EEG) findings in a cohort of normal children with newly diagnosed seizures.

In the initial assessment of children with new-onset seizures, the suggestion that electroencephalography (EEG) should be standard and that magnetic resonance imaging (MRI) should be optional has been questioned. The purposes of this study were to (1) describe the frequency of EEG and MRI abnormalities and (2) explore relationships between MRI and EEG findings to determine their relevance in the assessment of children with new-onset seizures who are otherwise developing normally. As part of an ongoing, prospective study of children with new-onset seizures, we studied 181 children (90 girls and 91 boys). Children were entered into the study within 3 months of their first-recognized seizure. The association between EEG and MRI abnormalities was explored using a chi-square test. Abnormal MRI findings were found in 32.6% (n = 59) of the sample. The EEG and MRI results agreed with respect to classification into normal or abnormal in 37% (n = 67). Of the 50 children with a normal EEG, however, 21 (42%) were found to have an abnormal MRI. We found an unexpectedly high frequency of imaging abnormalities in our sample of otherwise normal children, although the significance of these findings is not clear. Follow-up of these patients will help us interpret the importance of the abnormalities. Despite our relatively small sample, however, our findings indicate that a normal EEG does not reliably predict a normal MRI in children with first seizures.

Brain↗
PubMed2005

Activity and connectivity of brain mood regulating circuit in depression: a functional magnetic resonance study.

BACKGROUND: Functional imaging studies indicate that imbalances in cortico-limbic activity and connectivity may underlie the pathophysiology of MDD. In this study, using functional Magnetic Resonance Imaging (fMRI), we investigated differences in cortico-limbic activity and connectivity between depressed patients and healthy controls. METHODS: Fifteen unmedicated unipolar depressed patients and 15 matched healthy subjects underwent fMRI during which they first completed a conventional block-design activation experiment in which they were exposed to negative and neutral pictures. Next, low frequency blood oxygenation dependent (BOLD) related fluctuations (LFBF) data were acquired at rest and during steady-state exposure to neutral, positive and negative pictures. LFBF correlations were calculated between anterior cingulate cortex (ACC) and limbic regions--amygdala (AMYG), pallidostriatum (PST) and medial thalamus (MTHAL) and used as a measure of cortico-limbic connectivity. RESULTS: Depressed patients had increased activation of cortical and limbic regions. At rest and during exposure to neutral, positive, and negative pictures cortico-limbic LFBF correlations were decreased in depressed patients compared to healthy subjects. CONCLUSIONS: The finding of increased activation of limbic regions and decreased LFBF correlations between ACC and limbic regions is consistent with the hypothesis that decreased cortical regulation of limbic activation in response to negative stimuli may be present in depression.

Adult↗
PubMed2005

Media violence exposure and executive functioning in aggressive and control adolescents.

The relationship between media violence exposure and executive functioning was investigated in samples of adolescents with no psychiatric diagnosis or with a history of aggressive-disruptive behavior. Age-, gender-, and IQ-matched samples of adolescents who had no Diagnostic and Statistical Manual of Mental Disorders-fourth edition (DSM-IV; American Psychiatric Association, 1994) diagnosis (N = 27) and of adolescents who had DSM-IV Disruptive Behavior Disorder diagnoses (N = 27) completed measures of media violence exposure and tests of executive functioning. Moderate to strong relationships were found between higher amounts of media violence exposure and deficits in self-report, parent-report, and laboratory-based measures of executive functioning. A significant diagnosis by media violence exposure interaction effect was found for Conners' Continuous Performance Test scores, such that the media violence exposure-executive functioning relationship was stronger for adolescents who had Disruptive Behavior Disorder diagnoses. Results indicate that media violence exposure is related to poorer executive functioning, and this relationship may be stronger for adolescents who have a history of aggressive-disruptive behavior.

Adolescent↗
PubMed2005

Antidepressant effect on connectivity of the mood-regulating circuit: an FMRI study.

The mechanisms by which antidepressant-induced neurochemical changes lead to physiological changes in brain circuitry and ultimately an antidepressant response remain unclear. This study investigated the effects of sertraline, a selective serotonin reuptake inhibitor antidepressant, on corticolimbic connectivity, using functional magnetic resonance imaging (fMRI). In all, 12 unmedicated unipolar depressed patients and 11 closely matched healthy control subjects completed two fMRI scanning sessions at baseline and after 6 weeks. Depressed patients received treatment with sertraline between the two sessions. During each fMRI session, subjects first completed a conventional block-design experiment. Next, connectivity between cortical and limbic regions was measured using correlations of low-frequency blood oxygen level-dependent (BOLD) fluctuations (LFBF) during continuous exposure to neutral, positive, and negative pictures. At baseline, depressed patients had decreased corticolimbic LFBF correlations compared to healthy subjects during the resting state and on exposure to emotionally valenced pictures. At rest and on exposure to neutral and positive pictures, LFBF correlation between the anterior cingulate cortex and limbic regions was significantly increased in patients after treatment. However, on exposure to negative pictures, corticolimbic LFBF correlations remained decreased in depressed patients. The results of this study are consistent with the hypothesis that antidepressant treatment may increase corticolimbic connectivity, thereby possibly increasing the regulatory influence of cortical mood-regulating regions over limbic regions.

Adult↗
PubMed2005

Adolescents with disruptive behavior disorder investigated using an optimized MR diffusion tensor imaging protocol.

Adolescents with disruptive behavior disorder (DBD) and controls were investigated using an optimized MR diffusion tensor imaging (DTI) protocol in order to assess any possible structural abnormalities associated with DBD. Thirty-six patients and 40 normal subjects were examined. The extracted diffusion fractional anisotropy (FA) results demonstrate that for the DBD patients there is significantly reduced FA in both the frontal and left temporal regions. The largest brain area with significantly reduced FA is located within the arcuate fasciculus, which has projections extending from the temporal lobe to the frontal lobe along the lateral ventricle, lateral to the tapetum. The reduced FA reflects directly a lower extent of myelination and less coherent fiber track structures in the fasciculus, which in turn may indicate communication weakness among the associated cortical areas. The detected white matter microstructural abnormality, therefore, may be related to the developmental deficits observed in the patient group.

Adolescent↗
PubMed2004

Lesion-induced pseudo-dominance at functional magnetic resonance imaging: implications for preoperative assessments.

OBJECTIVE: To illustrate how lesion-induced neurovascular uncoupling at functional magnetic resonance imaging (fMRI) can mimic hemispheric dominance opposite the side of a lesion preoperatively. METHODS: We retrospectively reviewed preoperative fMRI mapping data from 50 patients with focal brain abnormalities to establish patterns of hemispheric dominance of language, speech, visual, or motor system functions. Abnormalities included gliomas (31 patients), arteriovenous malformations (AVMs) (11 patients), other congenital lesions (4 patients), encephalomalacia (3 patients), and tumefactive encephalitis (1 patient). A laterality ratio of fMRI hemispheric dominance was compared with actual hemispheric dominance as verified by electrocortical stimulation, Wada testing, postoperative and posttreatment deficits, and/or lesion-induced deficits. fMRI activation maps were generated with cross-correlation (P < 0.001) or t test (P < 0.001) analysis. RESULTS: In 50 patients, a total of 85 functional areas were within 5 mm of the edge of a potentially resectable lesion. In 23 of these areas (27%), reduced fMRI signal in perilesional eloquent cortex in conjunction with preserved or increased signal in homologous contralateral brain areas revealed functional dominance opposite the side of the lesion. This suggested possible lesion-induced transhemispheric cortical reorganization to homologous brain regions (homotopic reorganization). In seven patients, however, the fMRI data were inconsistent with other methods of functional localization. In two patients with left inferior frontal gyrus gliomas and in one patient with focal tumefactive meningoencephalitis, fMRI incorrectly suggested strong right hemispheric speech dominance. In two patients with lateral precentral gyrus region gliomas and one patient with a left central sulcus AVM, the fMRI pattern incorrectly suggested primary corticobulbar motor dominance contralateral to the side of the lesion. In a patient with a right superior frontal gyrus AVM, fMRI revealed pronounced left dominant supplementary motor area activity in response to a bilateral complex motor task, but right superior frontal gyrus perilesional hemorrhage and edema subsequently caused left upper-extremity plegia. Pathophysiological factors that might have caused neurovascular uncoupling and facilitated pseudo-dominance at fMRI in these patients included direct tumor infiltration, neovascularity, cerebrovascular inflammation, and AVM-induced hemodynamic effects. Sixteen patients had proven (1 patient), probable (2 patients), or possible (13 patients) but unproven lesion-induced homotopic cortical reorganization. CONCLUSION: Lesion-induced neurovascular uncoupling causing reduced fMRI signal in perilesional eloquent cortex, in conjunction with normal or increased activity in homologous brain regions, may simulate hemispheric dominance and lesion-induced homotopic cortical reorganization.

Adult↗
PubMed2002

American Society of Neuroradiology research survey 2001.

RATIONALE AND OBJECTIVES: Research is a critical component of the mission of academic radiology, and success in research is necessary for the future of neuroradiology. Thus, the authors set out to establish a baseline of research activities of American Society of Neuroradiology (ASNR) members. MATERIALS AND METHODS: The authors surveyed 100 fellowship program directors. The survey was Web based, with recruitment from the ASNR Fellowship Database survey site and with e-mail and fax solicitations to the Web site. Questions focused on neuroradiologist and neuroradiology fellow involvement in research. RESULTS: Forty-eight of the 100 program directors (48%) responded. Several key findings emerged: (a) About one-third of fellowship programs require all fellows to do some research, with most fellows receiving less than 1 day per week of academic time; (b) just over half of the programs expect fellows to publish a paper; (c) about two-thirds of academic neuroradiologists get at least 1 academic day per week; (d) most academic neuroradiologists perform research, but most of this research is unfunded; and (e) about nine of 10 academic sections have at least one neuroradiologist with some extramural funding. CONCLUSION: The relative lack of extramural funding among academic neuroradiologists is a reality that is probably multifactorial; however, there may be a direct relationship between amount of academic time free from clinical duties and successful competition for funding. The time (and, thus, financial) support of research-oriented fellows and faculty should be increased.

Canada↗
PubMed2002

Assessment and cost comparison of sleep-deprived EEG, MRI and PET in the prediction of surgical treatment for epilepsy.

Our aim was to determine if less expensive interictal indices can predict which epilepsy patients may benefit from the more expensive comprehensive pre-surgical evaluation. Surgical treatment was determined based on the results of a comprehensive inpatient continuous video-EEG monitoring. This evaluation included three interictal tests, which were reviewed retrospectively-2 hour-sleep-deprived electroencephalogram (SDEEG), magnetic resonance imaging (MRI), and positron emission tomography (PET). Sixty-nine patients were evaluated with 35 patients having focal resection (33 temporal, two frontal). When two or more interictal tests were positive, 77% (27 /35) went to surgery, but when one test was positive 23% (8 /34) had surgery. When all tests were negative, only a single patient (1 /13 or 7.7%) had surgery, a frontal resection. The positive predictive value for any single interictal test was 68%, while it was higher for any combination of two positive tests (77-83%). PET was the most sensitive (0.86) single interictal test, compared to SDEEG (0.66) and MRI (0.66). The odds ratio for predicting surgical treatment for a positive PET, SDEEG, or MRI was 8.57, 4.01, and 4.01, respectively. MRI was three and PET was six times the cost of a SDEEG. The combination of SDEEG and MRI had the best cost/PPV ratio. Seventy-nine percent (11 /14) of the patients with three positive tests were seizure free following focal resection compared to 43% (9 /21) when less than three tests were positive ( P<or= 0.05). Interictal tests may predict which patients are most likely to benefit from comprehensive pre-surgical evaluation. Two or more positive tests are the most predictive. If all tests are negative, it is unlikely that the patient would qualify for surgical treatment. The combination of SDEEG and MRI may be more cost-effective as outpatient screening tools.

Adolescent↗
PubMed2002

Multiple sclerosis: low-frequency temporal blood oxygen level-dependent fluctuations indicate reduced functional connectivity initial results.

PURPOSE: To study the correlation of low-frequency blood oxygenation level-dependent (BOLD) fluctuations on magnetic resonance (MR) images obtained of the left- and right-hemisphere primary motor regions in healthy control subjects and patients with multiple sclerosis (MS). MATERIALS AND METHODS: Sixteen healthy volunteers and 20 patients with MS underwent MR imaging with a 1.5-T imager by using a protocol designed to monitor low-frequency BOLD fluctuations. Data for low-frequency BOLD fluctuations were acquired with subjects at rest and during continuous performance of a bilateral finger-tapping task. These data were low-pass filtered (<0.08 Hz), and cross correlations of all acquired pixels to a region of interest in the left precentral gyrus were calculated. Confidence levels were calculated from the cross correlations. The fraction of pixels in the right precentral gyrus above a confidence level of 95% for correlation with the left precentral gyrus was calculated for each subject. RESULTS: A plot of the fraction of the right precentral gyrus with high correlation with the left precentral gyrus for the finger-tapping state versus the resting state showed a clear discrimination between patients with MS and control subjects. Compared with control subjects, patients with MS generally had a smaller fraction of the pixels in the right precentral gyrus above the confidence level. This finding indicates that our method results in greater than 60% sensitivity and 100% specificity for discriminating patients with MS from control subjects. No significant correlation was found between clinical measures of MS disease and correlations of low-frequency BOLD fluctuations between left and right precentral gyri. CONCLUSION: On the basis of the connectivity measure of low-frequency BOLD fluctuations, patients with MS exhibited lower functional connectivity between right- and left-hemisphere primary motor cortices when compared with that in control subjects.

Adult↗
PubMedDate not supplied

Visual object agnosia and pure word alexia: correlation of functional magnetic resonance imaging and lesion localization.

We present a case of a 64-year-old, right-handed female with a metastatic breast cancer lesion involving the left posterior inferior temporal lobe causing complete loss of the ability to recognize visually common objects and words. After her symptoms resolved on corticosteroid therapy, functional magnetic resonance imaging (fMRI) mapping demonstrated strong left-hemispheric dominance for word recognition and right-hemispheric dominance for object recognition. The case illustrates the relationships among ventral occipito-temporal cortical activation, lesion localization, and lesion-induced deficits of higher visual function. The relationship between hemispheric dominance determined by fMRI and risk of postoperative deficit depends on the specific visual function of interest.

Agnosia↗
PubMedDate not supplied

Media violence exposure and frontal lobe activation measured by functional magnetic resonance imaging in aggressive and nonaggressive adolescents.

OBJECTIVE: To understand better the relation between media violence exposure, brain functioning, and trait aggression, this study investigated the association between media violence exposure and brain activation as measured by functional magnetic resonance imaging (fMRI) in groups of normal adolescents and adolescents with disruptive behavior disorder (DBD) with aggressive features. METHODS: Seventy-one participants underwent neuropsychologic evaluation and assessment of exposure to violent media. Subjects also were evaluated with fMRI while performing a counting Stroop (CS) task. RESULTS: Frontal lobe activation was reduced in aggressive subjects compared with control subjects. In addition, differences in frontal lobe activation were associated with differences in media violence exposure. Specifically, activation during performance of the CS in control subjects with high media violence exposure resembled that seen in DBD subjects. CONCLUSIONS: Our findings suggest that media violence exposure may be associated with alterations in brain functioning whether or not trait aggression is present.

Adolescent↗