Table 2:

Parameters among the tap-positive, tap-negative, and control groups

	Mean (72 Total)	Mean (24 Tap-Positive)	P Value^{^1a}	P Value^{^2b}	Mean (25 Tap-Negative)	P Value^{^3c}	Mean (23 Controls)
Total ventricle volume (mL)	123	157	<.001^{^d}	.060	135	<.001^{^d}	75.4
Total ventricle volume ratio (%)	8.1	10.5	<.001^{^d}	.017^{^d}	8.8	<.001^{^d}	5
Bilateral ventricle volume (mL)	114	147	<.001^{^d}	.060	125	<.001^{^d}	66.9
Bilateral ventricle volume ratio (%)	7.5	9.8	<.001^{^d}	.013^{^d}	8.2	<.001^{^d}	4.4
Total subarachnoid space volume (mL)	270	251	.678	.010^{^d}	294	.127	264
Total subarachnoid space volume ratio (%)	18.0	16.8	.587	.030^{^d}	19.3	.223	17.8
CSF volume of frontal convexity (mL)	51.1	41.0	.003^{^d}	.016^{^d}	52.1	.218	51.1
CSF volume of parietal convexity (mL)	42.4	28.4	<.001^{^d}	<.001^{^d}	44.1	.162	42.4
CSF volume of Sylvian fissure and basal cistern (mL)	119	121	.030^{^d}	.077	136	<.001^{^d}	119
CSF volume of posterior fossa (mL)	57.1	59.1	.232	1.000	58.9	.226	57.1
Upper-to-lower subarachnoid space ratio	0.55	0.37	<.001^{^d}	.008^{^d}	0.49	<.001^{^d}	0.79
Evans Index	0.31	0.34	<.001^{^d}	.028^{^d}	0.32	.004^{^d}	0.29
Y-Evans Index	0.22	0.23	.001^{^d}	.053	0.22	.095	0.21
Z-Evans Index	0.38	0.43	<.001^{^d}	.002^{^d}	0.39	<.001^{^d}	0.31
X-Max Index	0.63	0.65	<.001^{^d}	.073	0.64	<.001^{^d}	0.60
Y-Max Index	0.63	0.67	<.001^{^d}	.048^{^d}	0.64	.001^{^d}	0.58
Z-Max Index	0.70	0.74	<.001^{^d}	.613	0.74	<.001^{^d}	0.62
Callosal angle (degree)	80.9	66.2	<.001^{^d}	.117	73.4	<.001^{^d}	104

Note:—Max indicates maximum.
↵a P value¹: probability value for the Mann-Whitney-Wilcoxon test between the tap-positive group and controls.
↵b P value²: probability value for the Mann-Whitney-Wilcoxon test between the tap-positive and tap-negative groups.
↵c P value³: probability value for the Mann-Whitney-Wilcoxon test between the tap-negative group and controls.
↵d Significant.