White matter lesions in patients with idiopathic normal pressure hydrocephalus and in an age-matched control group: A comparative study

OBJECTIVE: To compare the occurrence of periventricular lesions (PVLs) and deep white matter lesions (DWMLs) in elderly patients with idiopathic normal pressure hydrocephalus (NPH) and in an age-matched control group. METHODS: PVLs and DWMLs were evaluated using T2-weighted magnetic resonance scans of 37 patients with idiopathic NPH and 35 participants from an age-matched control group. All patients with idiopathic NPH included in this study improved after shunting. The control group consisted of 16 healthy elderly persons and 19 patients with depression. To allow quantitative assessment and comparison, scores for PVLs and DWMLs were calculated. Furthermore, possible correlations between white matter lesion scores, ventricular width, and age were investigated. RESULTS: There was a significantly higher incidence of PVLs and DWMLs in patients with idiopathic NPH. The mean total PVL was 12.1 (range, 2-24) in the NPH group and 3.9 (range, 0-10) in the control group (P < 0.001). The mean total DWML score was 12.9 (range, 3-24) in the NPH group and 4.5 (range, 0-16) in the control group (P < 0.001). There were significant correlations between the severity of PVL and DWML scores in both groups. Only a weak positive correlation between the severity of DWMLs and age was found in the NPH group, whereas this correlation was significant in the control group. There was a significant negative correlation between the width of the anterior horns and the severity of both PVLs and DWMLs in patients with NPH; however, positive correlations were found in the control group. CONCLUSION: Elderly patients with idiopathic NPH have more frequent and more severe PVLs and DWMLs than people in age-matched control groups. Our data suggest a frequent co-occurrence of idiopathic NPH and vascular subcortical encephalopathy; however, they do not support a direct causal relationship.