Volumetric Assessment of Hippocampus and Subcortical Gray Matter Regions in Alzheimer Disease and Amnestic Mild Cognitive Impairment.

BACKGROUND: Quantitative MRI assessment methods have limited utility due to a lack of standardized methods and measures for Alzheimer disease (AD) and amnestic mild cognitive impairment (aMCI). OBJECTIVE: To employ a relatively new and easy-to-use quantitative assessment method to reveal volumetric changes in subcortical gray matter (GM) regions, hippocampus, and global intracranial structures as well as the diagnostic performance and best thresholds of total hippocampal volumetry in individuals with AD and those with aMCI. METHOD: A total of 74 individuals-37 with mild to moderate AD, 19 with aMCI, and 18 with normal cognition (NC)-underwent a 3T MRI. Fully automated segmentation and volumetric measurements were performed. RESULTS: The AD and aMCI groups had smaller volumes of amygdala, nucleus accumbens, and hippocampus compared with the NC group. These same two groups had significantly smaller total white matter volume than the NC group. The AD group had smaller total GM volume compared with the aMCI and NC groups. The thalamus in the AD group showed a subtle atrophy. There were no significant volumetric differences in the caudate nucleus, putamen, or globus pallidus between the groups. CONCLUSION: The amygdala and nucleus accumbens showed atrophy comparable to the hippocampal atrophy in both the AD and aMCI groups, which may contribute to cognitive impairment. Hippocampal volumetry is a reliable tool for differentiating between AD and NC groups but has substantially less power in differentiating between AD and aMCI groups. The loss of total GM volume differentiates AD from aMCI and NC.

DWI-based MR thermometry: could it discriminate Alzheimer's disease from mild cognitive impairment and healthy subjects?

PURPOSE: The aim of this study is to compare lateral ventricular cerebrospinal fluid (CSF) temperature of the patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy subjects (HS) using diffusion-weighted imaging (DWI)-based magnetic resonance (MR) thermometry. METHODS: Seventy-two patients (37 AD, 19 MCI, 16 HS) who underwent 3-T MR examination from September 2018 to August 2019 were included in this study. Smoking habits, education level, disease duration, and comorbidity status were recorded. Patients were assessed using Mini-Mental State Examination (MMSE) and the Clinical Dementia Rating (CDR) score. Brain temperatures were measured using DWI-based MR thermometry. Group comparisons of brain temperature were performed using the Pearson chi-square, Mann-Whitney, and Kruskal-Wallis tests. Further analysis was performed using the post hoc Bonferroni test. Receiver operating characteristic (ROC) analysis was also used. RESULTS: A CDR score of 0.5, 1, and 2 was 2 (5.4%), 14 (37.8%), and 21 (56.8%) in AD, respectively. The median MMSE score had significant differences among groups and also in pairwise comparisons. The median CSF temperature (°C) values showed statistically significant difference among groups (HS: 38.5 °C, MCI: 38.17 °C, AD: 38.0 °C). The post hoc Mann-Whitney U test indicated a significant difference between AD patients and HS (p = 0.009). There were no significant CSF temperature differences in other pairwise comparisons. CONCLUSION: Lower CSF temperatures were observed in AD patients than in HS, probably due to decreased brain metabolism in AD. DWI-based MR thermometry as a noninvasive imaging method enabling the measurement of CSF temperatures may contribute to the diagnosis of AD.

Cortical plasticity causes useless hand syndrome in multiple sclerosis: a neurophysiological study in a rare case.

BACKGROUND: Useless Hand Syndrome (UHS) is a rare clinical manifestation of an upper cervical cord lesion, which is most commonly associated with multiple sclerosis (MS). The pathophysiological mechanism underlying UHS remains unclear. CASE: We report a 25-year-old woman, who described numbness in her left upper extremity. Cervical magnetic resonance imaging revealed a posterior upper cervical cord lesion. There was no cortical lesion that could explain the clinical findings. We measured (1) short-latency afferent inhibition (SAI) by obtaining motor evoked potentials as an indicator of sensorimotor integration and (2) somatosensorial temporal discrimination threshold (STDT) to display central somatosensory pathway function. In the right cerebral hemisphere, we found an excessive increase in STDT and no inhibition in the SAI paradigm. CONCLUSIONS: These findings indicate that impairment of sensorimotor integration and central processing of sensory stimuli cause useless hand syndrome.