The role of transcranial sonography in differentiation of dementia subtypes: an introduction of a new diagnostic method.

Abstract

Transcranial sonography (TCS) is increasingly used for the diagnosis of neurodegenerative disorders. We assessed the role of third ventricle width (TVW), midbrain area (MA), and midbrain circumference (MC) by TCS for diagnosis and differentiation of dementia. A cross-sectional study was designed in 59 patients with dementia including 19 patients with Alzheimer's disease (AD), 10 Dementia with Lewy bodies (DLB), 23 Frontotemporal dementia (FTD) and 7 Vascular dementia (VaD), and 22 normal-cognition individuals. Both case and control groups were matched by age, sex, and educational level. The dementia patients were divided into two subgroups: cortical-dominant dementia (CDD) including AD and FTD; and subcortical-dominant dementia (SDD) including DLB and VaD. TCS was performed through a temporal window, in which the size of TVW and midbrain was measured by trans-thalamic and trans-mesencephalic planes, respectively. The mean TVW was 0.85 ± 0.3cm and 0.66 ± 0.2cm in dementia patients and the control group, respectively (p < 0.01). The MA/MC were smaller in dementia patients compared with the control group (p < 0.05 and p < 0.01). The TVW in CDD (p = 0.003) and SDD (p = 0.027), but only MA/MC in SDD (p < 0.05), was statistically different compared with the control group. The measurement of TVW and midbrain size by TCS can be used for diagnosis and differentiation of dementia. Patients with CDD and SDD have larger TVW than the control group, whereas patients with SDD have smaller midbrain sizes.