Michael G. Dwyer

Bio: Michael G. Dwyer is an academic researcher from State University of New York System. The author has contributed to research in topics: Multiple sclerosis & Atrophy. The author has an hindex of 46, co-authored 226 publications receiving 6987 citations. Previous affiliations of Michael G. Dwyer include Women & Children's Hospital of Buffalo & University of Bradford.

Neocortical Atrophy, Third Ventricular Width, and Cognitive Dysfunction in Multiple Sclerosis

Abstract: Results: Patients with secondary progressive MS had more atrophy than patients with relapsing-remitting MS and controls Neocortical volume was significantly correlated with all neuropsychological measures, withr values ranging from 029 to 058 Third ventricular width was retained in most stepwise regression analyses predicting cognitive impairment in patients with MS and distinguishing secondary progressive from relapsingremitting courses of MS Conclusions: We confirm an association between neocortical volume and multiple cognitive domains in MS, although neocortical volume did not explain significantly more variance than other magnetic resonance imaging measures Of the magnetic resonance imaging variables studied, third ventricular width was retained in most regression models

Basal ganglia, thalamus and neocortical atrophy predicting slowed cognitive processing in multiple sclerosis

Abstract: Information-processing speed (IPS) slowing is a primary cognitive deficit in multiple sclerosis (MS). Basal ganglia, thalamus and neocortex are thought to have a key role for efficient information-processing, yet the specific relative contribution of these structures for MS-related IPS impairment is poorly understood. To determine if basal ganglia and thalamus atrophy independently contribute to visual and auditory IPS impairment in MS, after controlling for the influence of neocortical volume, we enrolled 86 consecutive MS patients and 25 normal controls undergoing 3T brain MRI and neuropsychological testing. Using Sienax and FIRST software, neocortical and deep gray matter (DGM) volumes were calculated. Neuropsychological testing contributed measures of auditory and visual IPS using the Paced Auditory Serial Addition Test (PASAT) and the Symbol Digit Modalities Test (SDMT), respectively. MS patients exhibited significantly slower IPS relative to controls and showed reduction in neocortex, caudate, putamen, globus pallidus, thalamus and nucleus accumbens volume. SDMT and PASAT were significantly correlated with all DGM regions. These effects were mitigated by controlling for the effects of neocortical volume, but all DGM volumes remained significantly correlated with SDMT, putamen (r = 0.409, p < 0.001) and thalamus (r = 0.362, p < 0.001) having the strongest effects, whereas for PASAT, the correlation was significant for putamen (r = 0.313, p < 0.01) but not for thalamus. We confirm the significant role of thalamus atrophy in MS-related IPS slowing and find that putamen atrophy is also a significant contributor to this disorder. These DGM structures have independent, significant roles, after controlling for the influence of neocortex atrophy.

Effect of a Cerebral Protection Device on Brain Lesions Following Transcatheter Aortic Valve Implantation in Patients With Severe Aortic Stenosis: The CLEAN-TAVI Randomized Clinical Trial

Abstract: Importance Stroke remains a major predictor of mortality after transcatheter aortic valve implantation (TAVI). Cerebral protection devices might reduce brain injury as determined by diffusion-weighted magnetic resonance imaging (DWMRI). Objective To determine the effect of a cerebral protection device on the number and volume of cerebral lesions in patients undergoing TAVI. Design, Setting, and Participants Investigator-initiated, single center, blinded, randomized clinical trial in higher-risk patients with severe aortic stenosis undergoing TAVI at the University of Leipzig Heart Center. Brain MRI was performed at baseline, 2 days, and 7 days after TAVI. Between April 2013 and June 2014, patients were randomly assigned to undergo TAVI with a cerebral protection device (filter group) or without a cerebral protection device (control group). The last 1-month follow-up occurred in July 2014. Interventions TAVI with or without a cerebral protection device (filter system). Main Outcomes and Measures The primary end point was the numerical difference in new positive postprocedure DWMRI brain lesions at 2 days after TAVI in potentially protected territories. The first hierarchical secondary outcome was the difference in volume of new lesions after TAVI in potentially protected territories. Results Among the 100 enrolled patients, mean (SD) age was 80.0 (5.1) years in the filter group (n = 50) and 79.1 (4.1) years in the control group (n = 50), and the mean (SD) procedural risk scores (logistic EuroScores) were 16.4% (10.0%) in the filter group and 14.5% (8.7%) in the control group. For the primary end point, the number of new lesions was lower in the filter group, 4.00 (interquartile range [IQR], 3.00-7.25) vs 10.00 (IQR, 6.75-17.00) in the control group (difference, 5.00 [IQR, 2.00-8.00]; P 3 [95% CI, 159-353]) vs in the control group (527 mm 3 [95% CI, 364-830]) (difference, 234 mm 3 [95% CI, 91-406]; P = .001). Considering adverse events, 1 patient in the control group died prior to the 30-day visit. Life-threatening hemorrhages occurred in 1 patient in the filter group and 1 in the control group. Major vascular complications occurred in 5 patients in the filter group and 6 patients in the control group. One patient in the filter group and 5 in the control group had acute kidney injury, and 3 patients in the filter group had a thoracotomy. Conclusions and Relevance Among patients with severe aortic stenosis undergoing TAVI, the use of a cerebral protection device reduced the frequency of ischemic cerebral lesions in potentially protected regions. Larger studies are needed to assess the effect of cerebral protection device use on neurological and cognitive function after TAVI and to devise methods that will provide more complete coverage of the brain to prevent new lesions. Trial Registration clinicaltrials.gov Identifier:NCT01833052

Mechanisms of action of disease-modifying agents and brain volume changes in multiple sclerosis

Abstract: Disease-modifying agents (DMAs), including interferon beta (IFNbeta) and glatiramer acetate (GA), are the mainstays of long-term treatment of multiple sclerosis (MS). Other potent anti-inflammatory agents like natalizumab and different types of chemotherapeutics are increasingly being used for treatment of MS, particularly in patients with breakthrough disease activity. Brain volume (BV) loss occurs early in the disease process, accelerates over time, and may be only partially affected by DMA therapy. Low-dose, low frequency IFNbeta administered once weekly and GA appear to partially reduce BV decline over the second and third years of treatment. High dose, high frequency IFNbeta demonstrated no clear effect on BV loss during this time period. Current evidence suggests that changes in BV after immunoablation may not be due entirely to the resolution of edema but may be related to potential chemotoxicity of high dose cyclophosphamide. Natalizumab reduces the development of BV decline in the second and third years of treatment. IV immunoglobulin showed a positive effect on decelerating BV reduction in relapsing and advanced stages of MS. These differences between DMAs may be explained by the extent of their therapeutic effects on inflammation and on the balance between inhibition or promotion of remyelination and neuronal repair in the CNS. We described the mechanisms of action by which DMAs induce accelerated, non-tissue-related BV loss (pseudoatrophy) in the short term but, in the long run, may still potentially lead to permanent BV decline. The effects of corticosteroid therapy on changes in BV in patients with MS help clarify the mechanisms through which potent anti-inflammatory treatments may prevent, stabilize, or induce BV loss.

Cognitive impairment in multiple sclerosis

Abstract: Summary Multiple sclerosis (MS) is a progressive disease of the CNS that is characterised by widespread lesions in the brain and spinal cord. MS results in motor, cognitive, and neuropsychiatric symptoms, all of which can occur independently of one another. The common cognitive symptoms include deficits in complex attention, efficiency of information processing, executive functioning, processing speed, and long-term memory. These deficits detrimentally affect many aspects of daily life, such as the ability to run a household, participate fully in society, and maintain employment—factors that can all affect the overall quality of life of the patient. The increased use of neuroimaging techniques in patients with MS has advanced our understanding of structural and functional changes in the brain that are characteristic of this disease, although much remains to be learned. Moreover, examination of efforts to treat the cognitive deficits in MS is still in the early stages.

Contributions to Neuropsychological Assessment

Abstract: on to develop full blown Parkinson's disease with rigidity and bradykinesia in the next few years. For those interested in the mechanisms of tremor, there are the customary authoritative reviews by Llinas, De Long, Lamarre, Rothwell and Deuschl, but uncertainty remains with respect to the relative importance of central autonomous generators and instability of peripheral reflex loops. Well written chapters are also included on primary orthostatic tremor and its relationship to essential tremor, writing tremor, neuropathic tremor, midbrain tremor and the increasingly acknowledged psychogenic tremors. Complex interrelationship between dystonia and postural tremor is also covered in depth. This cornucopia will be coveted and dipped into by those neurologists with a special interest in abnormal movement disorders, but who would not consider themselves to have a research interest in tremor. However, for the majority of clinicians involved in the hurly burly of clinical practice, I suspect that regrettably time and cost factors will conspire together to keep this excellent book out of reach. ANDREW LEES