Abstract
ObjectivesThe pathological bases for the cognitive and neuropsychiatric symptoms in normal pressure hydrocephalus (NPH) have not been elucidated. However, the symptoms may indicate dysfunction of subcortical regions. Previously, volume reductions of subcortical deep grey matter (SDGM) structures have been observed in NPH patients. The present study used automated segmentation methods to investigate whether SDGM structure volumes are associated with cognitive and neuropsychiatric measures.MethodsFourteen NPH patients and eight healthy controls were included in the study. Patients completed neuropsychological tests of general cognition, verbal learning and memory, verbal fluency and measures of apathy and depression pre‐ and postshunt surgery. Additionally, patients underwent 3 Tesla T1‐weighted magnetic resonance imaging at baseline and 6 months postoperatively. Controls were scanned once. SDGM structure volumes were estimated using automated segmentation (FSL FIRST). Since displacement of the caudate nuclei occurred for some patients due to ventriculomegaly, patient caudate volumes were also estimated using manual tracing. Group differences in SDGM structure volumes were investigated, as well as associations between volumes and cognitive and neuropsychiatric measures in patients.ResultsVolumes of the caudate, thalamus, putamen, pallidum, hippocampus and nucleus accumbens (NAcc) were significantly reduced in the NPH patients compared to controls. In the NPH group, smaller caudate and NAcc volumes were associated with poorer performance on neuropsychological tests and increased severity of neuropsychiatric symptoms, while reduced volume of the pallidum was associated with better performance on the MMSE and reduced apathy.ConclusionsStriatal volume loss appears to be associated with cognitive and neuropsychiatric changes in NPH.
Highlights
Normal pressure hydrocephalus (NPH) is characterized by a build‐up of cerebrospinal fluid (CSF) in the brain which causes ventriculomeg‐ aly despite apparently normal CSF pressure at lumbar puncture
Caudate volumes obtained via automated and manual segmentation were significantly correlated at both pre‐ and postshunt suggesting that automated segmentation was satisfactory for the majority of patients
All of the subcortical deep grey matter (SDGM) structures apart from the amygdala were significantly reduced in the NPH patients compared to healthy controls, and remained so after adjusting for age and sex
Summary
Normal pressure hydrocephalus (NPH) is characterized by a build‐up of cerebrospinal fluid (CSF) in the brain which causes ventriculomeg‐ aly despite apparently normal CSF pressure at lumbar puncture. The pathological mechanisms underlying the cognitive and neuropsychiatric symptoms in NPH are not well established. The executive dysfunction in NPH may suggest impaired frontal lobe functioning,[6] there is inconsistent evidence for frontal involvement from imaging studies of regional cerebral blood flow (rCBF) in NPH.[6,7] The pattern of cognitive decline is consistent with dysfunction of subcortical structures and may indicate disruption to the subfrontal white matter, limbic connections or connections be‐ tween the frontal lobe and the subcortical deep grey matter (SDGM) structures.[8] impaired rCBF has been found in the periven‐ tricular white matter and in the basal ganglia.[7,9]
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