Single photon emission computed tomography, magnetic resonance imaging hyperintensity, and cognitive impairments in patients with vascular dementia

The clinical profile of cerebral small vessel disease: Toward an evidence-based identification of cognitive markers

There is no consensus on which test is more suited to outline the cognitive deficits of cerebral small vessel disease (cSVD) patients. We explored the ability of eight cognitive tests, selected in a previous systematic review as the most commonly used in this population, to differentiate among cSVD patients, controls, and other dementing conditions performing a meta-analysis of 86 studies. We found that cSVD patients performed worse than healthy controls in all tests while data on the comparison to neurodegenerative diseases were limited. We outlined a lack of data on these tests' accuracy on the diagnosis. Cognitive tests measuring processing speed were those mostly associated with neuroimaging cSVD markers. There is currently incomplete evidence that a single test could differentiate cSVD patients with cognitive decline from other dementing diseases. We make preliminary proposals on possible strategies to gain information about the clinical definition of cSVD that currently remains a neuroimaging-based one.

Brain perfusion SPECT imaging and acetazolamide challenge in vascular cognitive impairment

Cerebrovascular disease is recognized as a common cause of cognitive impairment and dementia, alone or coexisting with other neurodegenerative diseases, mostly Alzheimer's disease. Vascular cognitive impairment (VCI) is a part of the heterogenous disorders group related to cerebral vessel disease. Although age is one of the most important risk factors for VCI, other common cardiovascular risk factors are also involved. By investigating these risk factors, a high proportion of these cognitive disorders can be prevented and/or delayed. Until now, only treatment of midlife arterial hypertension has been recognized as a preventing factor of vascular dementia. Brain MRI is becoming the method of choice to investigate cerebral vascular pathologies. However, this form of morphological imaging remains inadequate and does not provide useful functional information during VCI exploration, despite which functional imaging such as brain perfusion single-photon computed tomography, performed in baseline conditions and/or after an acetazolamide challenge, is underutilized in VCI exploration. The common strategies for VCI screening have not been standardized until now, and therefore further long-term imaging studies are needed to establish early diagnostic protocols. The present review summarizes the potential benefits of brain perfusion single-photon computed tomography imaging and possible scintigraphic quantification of cerebral hemodynamic reserves in investigation of VCI.

Factors Associated with Outcome after Hemicraniectomy for Large Middle Cerebral Artery Territory Infarction

OBJECTIVE:

Large or malignant middle cerebral artery infarction is associated with a high mortality rate. Hemicraniectomy reduces intracranial pressure and has been demonstrated to increase survival. Questions remain regarding selection of patients for surgery and functional outcomes.

METHODS:

We retrospectively reviewed the charts, operative reports, and images of patients who underwent hemicraniectomy for cerebral infarction at our institution between 1990 and 2002. Stroke volume and craniectomy area image analyses were performed with National Institutes of Health Image J software. Short-term outcome was measured with the Glasgow Outcome Scale. The requirement for second surgical decompression was also used as a measure of short-term outcome. Outcome 1 year after stroke was assessed with mailed self-report questionnaires to patients or providers with answers yielding information pertinent to the Barthel Index for physical disability, the Reintegration to Normal Living Index, and the Zung Depression Index. Univariate and multivariate logistic regression analyses were used to consider factors associated with outcome.

RESULTS:

Thirty-eight patients with large hemispheric infarcts (average volume, 407 cm3) were treated with hemicraniectomy during the study period. Thirty-two patients survived more than 1 year after surgery. Twenty patients responded to a questionnaire scoring late physical disability (Barthel Index), quality of life (Reintegration to Normal Living Index), and depression (Zung Depression Index). The average Barthel Index score was 67. Barthel Index score and ability to walk were strongly correlated with age but not time to surgery, volume of infarction, or craniectomy size. Patients exhibited moderate to severe decrements in quality of life and increased incidence of depression across all age groups. Reoperation, an indicator for early operative failure, was required in six patients. These patients were significantly younger and had significantly higher volumes of cerebral infarction.

CONCLUSION:

Hemicraniectomy is life-saving treatment for large middle cerebral artery infarction. Good functional outcomes can be obtained but are less likely in older patients. Younger patients with large-volume strokes may benefit from multiple decompressions, if necessary.

Neuroimaging correlates of dementia rating scale performance at baseline and 12-month follow-up among patients with vascular dementia

The authors previously reported that subcortical hyperintensity (SH) and whole-brain volume (WBV) each covary with different subscale scores of the Mattis Dementia Rating Scale (MDRS) among vascular dementia (VaD) patients. The present longitudinal analysis examined these relationships for change. The authors found that SH volume increased and WBV decreased significantly over 12 months. At baseline, SH volume accounted for significant variance in MDRS total score and every subscale score, except Memory. WBV was unrelated to any MDRS measure. After 12 months, SH volume was related only to the Construction subscale score, whereas WBV accounted for the majority of variance in Attention and Memory subscale performance. These findings indicate that although SH volume increases with disease progression, the relative impact of SH volume on cognitive status decreases among patients with advanced VaD.

Role of white matter lesions, cerebral atrophy, and APOE on cognition in older persons with and without dementia: the Cache County, Utah, study of memory and aging

Neuropsychological, qualitative, and quantitative magnetic resonance imaging findings were examined in subjects with Alzheimer's disease (AD), non-AD dementia or mixed neuropsychiatric disorder, subjects characterized as mild/ambiguous, and controls, all with known apolipoprotein E (APOE) genotype. Neuropsychological tasks included an expanded Consortium to Establish a Registery for Alzheimer's Disease (J. T. Tschanz et al., 2000; K. A. Welsh, J. M. Hoffman, N. L. Earl, & M. W. Hanson 1994) battery and the Mini-Mental Status Examination (M. F. Folstein, S. E. Folstein, & P. R. McHugh, 1975). Periventricular white matter lesions were the most clinically salient, and generalized measures of cerebral atrophy were the most significant quantitative indicators. APOE genotype was unrelated to imaging or neuropsychological performance. Neuropsychological relationships with neuroimaging findings depend on the qualitative or quantitative method used.

Functional brain imaging applications to differential diagnosis in the dementias

PURPOSE OF REVIEW

The diagnosis of dementia rests on an improved knowledge and a better detection of early impairments, to which functional imaging can certainly contribute.

RECENT FINDINGS

Progress has been observed at different levels. First, the understanding of different dementias has benefited from explorations of the neural substrate of dementia symptoms and from research into new markers. Second, diverse variables (clinical, anatomical, biochemical) have been related to impaired cerebral activity in Alzheimer's disease and other dementias, and progress in image analysis and in multimodal data acquisition has allowed a better understanding of the significance of brain activity disturbances. Third, functional imaging has been applied in well-designed clinical studies, and has provided important arguments for the diagnosis of characteristic clinical syndromes in the dementias.

SUMMARY

The functioning of neural networks responsible for clinical symptoms in dementia remains an important research topic for functional imaging. The development of new tracers and new techniques for image processing should also improve the usefulness of brain imaging as a diagnostic tool.