Altered Microstructure in Corticospinal Tract in Idiopathic Normal Pressure Hydrocephalus: Comparison with Alzheimer Disease and Parkinson Disease with Dementia

Article Figures & Data

Download figure
Open in new tab
Download powerpoint
Fig 1.
Voxelization of part of the CST by tract-specific analysis. Tractographic images of the CST were generated by using the 2-ROI method of seed ROI in the motor cortex (A) and target ROI in the cerebral peduncle (B). C, Tractography of the CST is shown with a color-coded FA map (coronal section). Voxelization along the CST was performed between the uppermost part of the SLF (green area, arrow) and the posterior limb of the internal capsule by using dTV software.
Download figure
Open in new tab
Download powerpoint
Fig 2.
Visual evaluation of anisotropy color-coding tractography of the CST. Anisotropy color-coding tractography of the CST in a control subject (A) and a patient with iNPH (B) is shown, with b = 0 images. The areas defined by the yellow squares in A and B were used for visual evaluation in C and D. C, Type A (low anisotropy and rough). D, Type B (high anisotropy and straight).
Download figure
Open in new tab
Download powerpoint
Fig 3.
Examples of anisotropy color-coding tractography of the CST. Anisotropy color-coding tractography of the CST in patients with iNPH (Evans index: 0.31; A), AD (0.33; B), PDD (0.33; C), and a control subject (0.31; D) are shown, with b = 0 images. The areas defined by the yellow squares in A, B, C, and D are shown in E, F, G, and H, respectively.

Table 1:

Demographic and clinical data of patients with iNPH, AD, or PDD and control subjects

Characteristic	A, iNPH (n = 18)	B, AD (n = 11)	C, PDD (n = 11)	D, Control (n = 19)	P	Post Hoc Significance
Age (yr)	77.3 ± 4.7	72.1 ± 5.5	75.6 ± 5.5	75.6 ± 5.5	.222
Sex (M:F)	7:11	5:6	6:5	7:12	.805
MMSE score	22.1 ± 3.7	18.3 ± 6.7	22.4 ± 2.7	28.6 ± 0.0	<.001	A, B, C < D^a
Evans index	0.37 ± 0.04	0.29 ± 0.03	0.29 ± 0.04	0.28 ± 0.03	<.001	A > B, C, D^a
Vascular risk factor
Hypertension (%)	27.8	36.4	18.2	42.1	.561
Diabetes mellitus (%)	16.7	18.2	0.0	0	.157
Dyslipidemia (%)	22.2	27.3	18.2	0	.168

Table 2:

Tract-specific analysis and visual evaluation of tractography of the CST

	A, iNPH (n = 18)	B, AD (n = 11)	C, PDD (n = 11)	D, Control (n = 19)	P	Post Hoc Significance
Extent of leukoaraiosis (Fazekas classification)	2.06 ± 0.87	1.64 ± 0.92	1.27 ± 0.90	0.89 ± 0.81	.003	A > C, D^a
Tract-specific analysis
FA value	0.62 ± 0.03	0.54 ± 0.04	0.55 ± 0.04	0.55 ± 0.04	<.001	A > B, C, D^b
Axial eigenvalue	1.65 ± 0.10	1.49 ± 0.07	1.42 ± 0.08	1.43 ± 0.07	<.001	A > B, C, D^b
Radial eigenvalue	0.53 ± 0.08	0.56 ± 0.05	0.54 ± 0.05	0.54 ± 0.04	.422
Visual evaluation of tractography
Pattern B, n (%)	17 (94.4)	3 (27.2)	1 (9.1)	1 (5.3)	<.001	A > B, C, D^b

Table 3:

Diagnostic discrimination of iNPH patient group from other subject groups

Variable	Sensitivity	Specificity	Positive Predictive Value	Negative Predictive Value	Cutoff Value of Each Measure	Area Under Curve
FA value
Compared with AD	94	82	89	90	0.59	0.92
Compared with PDD	94	72	85	89	0.59	0.89
Compared with control	94	84	85	94	0.59	0.91
Compared with AD, PDD, and control	94	80	68	97	0.59	0.91
Axial eigenvalue
Compared with AD	94	82	89	90	1.52	0.95
Compared with PDD	100	82	90	100	1.48	0.96
Compared with control	100	84	86	100	1.50	0.98
Compared with AD, PDD, and control	94	83	71	97	1.52	0.97

Note:—Data (except for the cutoffs of FA values and axial eigenvalues) are shown as percentages. Receiver operating characteristic analysis was used to determine the optimum cutoff values for evaluating the usefulness of FA values and axial eigenvalues in differentiating iNPH from AD, PDD, and controls.