Correlation of neuropsychological, morphological and functional (regional cerebral blood flow and glucose utilization) findings in cerebral microangiopathy

Abstract

Cerebral microangiopathy, indicated in MRI by lacunar infarctions (LIs) and deep white matter lesions (DWMLs), is said to be accompanied by vascular dementia, which is reportedly caused by LI and DWML.

Methods: To confirm this assumption, 57 patients with cerebral microangiopathy were assessed for changes in regional cerebral blood flow (rCBF) and glucose utilization (rMRGlu) in both white matter and cortex, and these findings were correlated to the results of extensive neuropsychological testing (cognitive, mnestic and attentiveness tests), as well as to MRI findings. A special head holder ensured reproducibility of positioning during measurement of rCBF (99mTc-HMPAO SPECT) and rMRGlu (18F-FDG PET) and MRI. White matter and cortex were quantified with regions of interest defined on MRI and superimposed to corresponding PET/SPECT slices. The rMRGlu was calculated according to Sokoloff, and rCBF was determined from normalization to the cerebellum. LI and DWML were graded by number and extent. Brain atrophy was classified as no to slight inner and/or outer atrophy (Group A) or moderate-to-severe inner and outer atrophy (Group B).

Results: Even in severe DWMLs and in multiple LIs, rCBFs and rMRGlu values were not reduced. Analysis of variance identified atrophy and neuropsychological deficits as the main determinants for reduced rCBF and rMRGlu values (p < 0.05). However, 60% of patients (19 of 31) with neuropsychological deficits in attentiveness tests and 61% of patients (23 of 38) with mnestic deficits belonged to Group A and revealed decreased rCBF and rMRGlu values. Neuropsychological deficits correlated well with decreased rCBF and rMRGlu, whereas MRI patterns, such as LI and DWML, did not.

Conclusion: We conclude that LI and DWML are epiphenomena that morphologically characterize cerebral microangiopathy. Dementia or neuropsychological deficits, however, are exclusively reflected by functional criteria (rCBF and rMRGlu), as long as cerebral atrophy does not occur.