Table 2.

Comparisons of clinical scores before and after external lumbar drainage placement

		N	Mean rank	Sum of ranks	P value
Mini-mental State Examination	negative ranks	0	0	0	<0.001
	positive ranks	16	8.50	136.00
	ties	4
	total	20
Japanese Idiopathic Normal-Pressure Hydrocephalus Scale	negative ranks	13	7.00	91.00	0.001
	positive ranks	0	0	0
	ties	7
	total	13	7.00	91.00