Timo Erkinjuntti

Bio: Timo Erkinjuntti is an academic researcher from University of Western Ontario. The author has contributed to research in topics: Dementia & Centrum semiovale. The author has an hindex of 3, co-authored 3 publications receiving 374 citations.

Temporal lobe atrophy on magnetic resonance imaging in the diagnosis of early Alzheimer's disease.

Abstract: • Objective. —To evaluate the use of simple ratings and linear measures of atrophy in the temporal lobe structures obtained with magnetic resonance imaging coronal scans in the diagnosis of early Alzheimer's disease. Design. —Prospective series. The National Institute for Neurological Disorders and Stroke—Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment. Setting. —Dementia study in a university hospital. Subjects. —Patients with Alzheimer's disease (n=34), scoring 150 or more on the Extended Scale for Dementia, and age-matched healthy community volunteers (n=39) who had both magnetic resonance imaging coronal scans and a psychometric assessment using the Extended Scale for Dementia within 6 months were included. Measures. —Main measures: T1-weighted magnetic resonance imaging coronal scans, a 1.5-T system. The degree of atrophy rated (0 to 4) in both sides of the temporal neocortex, entorhinal cortex, hippocampal formation, temporal horns, third ventricle, lateral ventricles, and frontal and parietal cortex. Linear measures: the area of hippocampus and the maximal transverse width of temporal horns. Results. —Differentiation between patients with Alzheimer's disease and controls was limited by considerable variations in sensitivity and specificity. Receiver operating characteristics analysis revealed a clear order of discrimination, the entorhinal cortex and the temporal neocortex being the two best, followed by the temporal horns and hippocampal formation. For a given specificity of 90%, the corresponding sensitivity for the entorhinal cortex, temporal neocortex, temporal horns, and hippocampal formation was 95%, 63%, 56%, and 41 %, respectively. Linear measures differed significantly but showed considerable overlap. Conclusion. —The presence of rated atrophy in selected temporal structures makes the diagnosis of Alzheimer's disease more likely, but the absence does not rule out the possibility of early Alzheimer's disease.

Lack of difference in brain hyperintensities between patients with early Alzheimer's disease and control subjects.

Abstract: Objective: To rate magnetic resonance image signal hyperintensities in clearly defined white and deep gray matter areas in patients with early Alzheimer's disease and controls. Design: Prospective series. The National Institute for Neurological Disorders and Stroke—The Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment. Setting: University hospital, dementia study group. Subjects: Thirty-four patients with Alzheimer's disease. Thirty-eight age-matched healthy community volunteers. Measures: Frequency of hyperintensities in axial magnetic resonance images (1.5-T system) seen both in the proton density and T 2 -weighted scans examined in vascular centrencephalon, centrum semiovale, watershed, periventricular, and subcortical white matter. Periventricular hyperintensities classification include caps, thin lining, and smooth and irregular halo. Hyperintensities in other areas include small and large focal, focal confluent, and diffusely confluent. The hyperintensities were counted and rated using a five-point scale and the Fazekas method. Results: No difference in the ratings, frequency, or extent of the hyperintensities between patients with early Alzheimer's disease and controls. Majority of patients and controls had two or fewer hyperintensities and they were mostly small foci, caps, and thin linings. The hyperintensities are associated with arterial hypertension, diabetes, cardiac disorder, and age in different combinations, but not with Alzheimer's disease. Conclusion: Tiny hyperintensities on magnetic resonance images are frequent both in patients with early Alzheimer's disease and in healthy controls; most of the lesions are not related to brain ischemia. When age and vascular risk factors were taken into account, no difference between patients with early Alzheimer's disease and control subjects could be detected.

Diffuse vacuolization (spongiosis) and arteriolosclerosis in the frontal white matter occurs in vascular dementia.

Abstract: Objective: To examine quantitatively white-matter changes at different sites in patients with definite vascular dementia and Alzheimer's disease. Design: Prospective clinical and neuropathological series. Setting: University hospital clinics (Helsinki, Finland, and London, Ontario). Subjects: Twenty-two patients with a clinical and neuropathological diagnosis of vascular dementia and 20 patients with Alzheimer's disease. Measures: The frequencies of focal white-matter lesions, arteriolosclerosis, and cerebral amyloid angiopathy were assessed. Validated ratings and cell counts were done in the subcortical U-fiber, centrum semiovale, and periventricular areas of the frontal white matter. Degrees of abnormality (none, mild, moderate, severe) were rated for spongiosis (vacuolization of white matter), etat crible (wideningof perivascular spaces), myelin loss, oligodendrocyte density, axonal loss, and overall. Densities of oligodendrocytes and astrocytes (cells per square millimeter) were determined. Results: Patients with vascular dementia showed focal white-matter lesions and arteriolosclerosis more often than patients with Alzheimer's disease. The patients with vascular dementia also had significantly greater spongiosis (P Conclusion: In addition to focal infarcts, patients with vascular dementia showed widespread diffuse changes, including spongiosis and arteriolosclerosis, along with etat crible and myelin loss. White-matter changes in patients with Alzheimer's disease could not be related to infarction. Pathologic changes in small blood vessels are associated with diffuse white-matter changes and may have a distinct role in the genesis of vascular dementia.

A New Rating Scale for Age-Related White Matter Changes Applicable to MRI and CT

Abstract: Background and Purpose—MRI is more sensitive than CT for detection of age-related white matter changes (ARWMC). Most rating scales estimate the degree and distribution of ARWMC either on CT or on MRI, and they differ in many aspects. This makes it difficult to compare CT and MRI studies. To be able to study the evolution and possible effect of drug treatment on ARWMC in large patient samples, it is necessary to have a rating scale constructed for both MRI and CT. We have developed and evaluated a new scale and studied ARWMC in a large number of patients examined with both MRI and CT. Methods—Seventy-seven patients with ARWMC on either CT or MRI were recruited and a complementary examination (MRI or CT) performed. The patients came from 4 centers in Europe, and the scans were rated by 4 raters on 1 occasion with the new ARWMC rating scale. The interrater reliability was evaluated by using κ statistics. The degree and distribution of ARWMC in CT and MRI scans were compared in different brain areas. Results—...

Pathogenesis of Leukoaraiosis A Review

Abstract: Background Changes in the cerebral hemispheric white matter, detectable with increasing frequency by modern neuroimaging methods, are associated with aging and conceivably may contribute to the development of specific cognitive deficits. The pathogenesis of these cerebral white matter abnormalities (sometimes described as leukoaraiosis) is unknown. This review evaluates the available evidence in support of the hypothesis that the etiology of leukoaraiosis is related to a specific type of cerebral ischemia and highlights mechanisms by which ischemic injury to the brain may induce selected structural alterations limited to the cerebral white matter. Summary of Review The review is based on the critical analysis of over 100 publications (most appearing in the last decade) dealing with the anatomy and physiology of the arterial circulation to the cerebral white matter and with the pathogenesis of leukoaraiosis. Conclusions A significant number of clues support the hypothesis that some types of leukoaraiosis m...

Subcortical ischaemic vascular dementia

Abstract: Summary Vascular dementia is the second most common type of dementia. The subcortical ischaemic form (SIVD) frequently causes cognitive impairment and dementia in elderly people. SIVD results from small-vessel disease, which produces either arteriolar occlusion and lacunes or widespread incomplete infarction of white matter due to critical stenosis of medullary arterioles and hypoperfusion (Binswanger's disease). Symptoms include motor and cognitive dysexecutive slowing, forgetfulness, dysarthria, mood changes, urinary symptoms, and short-stepped gait. These manifestations probably result from ischaemic interruption of parallel circuits from the prefrontal cortex to the basal ganglia and corresponding thalamocortical connections. Brain imaging (computed tomography and magnetic resonance imaging) is essential for correct diagnosis. The main risk factors are advanced age, hypertension, diabetes, smoking, hyperhomocysteinaemia, hyperfibrinogenaemia, and other conditions that can cause brain hypoperfusion such as obstructive sleep apnoea, congestive heart failure, cardiac arrhythmias, and orthostatic hypotension. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) and some forms of cerebral amyloid angiopathy have a genetic basis. Treatment is symptomatic and prevention requires control of treatable risk factors.