Abstract 2986: Bilateral Thalamic Lesions in Subcortical Vascular Dementia

Abstract

Subcortical vascular dementia (SVaD) is categorized to the group of dementia due to the small-vessel disease which consists of lacunar infarcts, microbleeds and leuko-araiosis. However, the causative lesions and their relationship have not been clarified yet in SVaD. In order to elucidate the pathophysiology underlying SVaD, MR findings and vascular risk factors were analyzed in 31 patients (25 men and 6 women) who were diagnosed as having SVaD based on the NINDS-AIREN criteria. Their mean age was 75.7 years. Thirty-six non-demented patients with asymptomatic cerebral infarction (ACI) and 49 non-demented patients with symptomatic lacunar infarcts (SCI) served as disease controls. All subjects underwent 1.5 Tesla MRI including T1WI, T2WI, T2*WI, FLAIR and MR angiography. Numbers of lacunar infarcts and old microbleeds were counted in all MR slices, and the degree of leuko-araiosis was evaluated according the Fazekas’ categories. Laboratory studies included fibrinogen, d-dimer, serum lipid profile, glucose, plasma immunoreactive insulin (IRI) and brain natriuretic peptide (BNP). In the neuropsychological evaluation, MMSE, clock drawing test (CDT) and Benton’s visual retention test (BVRT) were carried out. In the results, the mean MMSE score was 13.0, and the mean CDT was 2.7/5.0. In the MR findings, the mean number of lacunar infarcts was 11.4, 15.2 and 17.2 for ACI, SCI and SVaD group, respectively. Thalamic lesions were detected in 30 (96.8%) of 31 SVaD patients, and 86.6% were lacunar infarcts whereas 13.3% were microbleeds on T2*WI. Bilateral thalamic lesions were detected in 66.7%, and the right-side and left-side lesions were seen in 16.6%, respectively. Antero-medial thalamic lesion was detected in 23.3%. No bilateral thalamic lesions were found in ACI or SCI group. Microbleeds were detected in 90% of SVaD patients. The mean number of microbleeds was 1.3, 2.1 and 5.8 for ACI, SCI and SVaD group, respectively. In the laboratory studies, the mean fibrinogen was significantly greater in SVaD group than in ACI or SCI group. The mean insulin was significantly greater in SVaD group than in ACI and SCI group. Advanced leuko-araiosis (Grade II and III) was seen in 87.1% of SVaD patients, whereas 52.8% of ACI patients and 34.7% of SCI patients. In the laboratory studies, the mean fibrinogen, IRI and BNP were significantly greater in SVaD group than in ACI or SCI group (p<0.05). The mean ratio of LDL-cholesterol to HDL-cholesterol was significantly greater in SVaD and SCI groups than in ACI group (p<0.05). In the present results, thalamic lesions, especially bilateral thalamic lesions, were detected frequently in SVaD patients. As thalamus plays an important role in both medial limbic and basolateral limbic systems which mediate cognitive information processing including memory and emotion, thalamic lesions may redound to the formation of SVaD.