Note 17 - Condensed Consolidating Financial Information of Guarantor Subsidiaries (Details) - Consolidating Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Condensed Income Statements, Captions [Line Items]
NET SALES	$ 96,712	$ 102,441
COST OF SALES (exclusive of amortization shown separately below)	34,642	36,827
GROSS PROFIT	62,070	65,614
OPERATING EXPENSES:
Research and development	6,830	7,078
Selling and marketing	13,987	15,056
Distribution	4,419	5,040
General and administrative	10,746	10,884
Amortization expense	13,578	13,682
Total operating expenses	49,560	51,740
INCOME (LOSS) FROM OPERATIONS	12,510	13,874
NON-OPERATING (EXPENSE) INCOME:
Interest income	42	56
Interest expense	(22,492)	(22,298)
Other, net	(127)	76
Total non-operating	(22,577)	(22,166)
(LOSS) INCOME BEFORE INCOME TAXES	(10,067)	(8,292)
(BENEFIT) PROVISION FOR INCOME TAXES	(2,850)	(2,813)
NET (LOSS) INCOME BEFORE EARNINGS OF CONSOLIDATED SUBSIDIARIES	(7,217)	(5,479)
NET (LOSS) INCOME	(7,217)	(5,479)
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
NET SALES	(17,192)	(18,014)
COST OF SALES (exclusive of amortization shown separately below)	(17,192)	(18,014)
NON-OPERATING (EXPENSE) INCOME:
Interest income	(22)	(25)
Interest expense	22	25
Net (loss) income of consolidated subsidiaries	527	338
NET (LOSS) INCOME	527	338
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
NET SALES	63,887	66,268
COST OF SALES (exclusive of amortization shown separately below)	20,264	20,775
GROSS PROFIT	43,623	45,493
OPERATING EXPENSES:
Research and development	2,639	2,640
Selling and marketing	6,401	6,237
Distribution	2,443	2,680
General and administrative	7,288	7,261
Amortization expense	11,972	11,971
Total operating expenses	30,743	30,789
INCOME (LOSS) FROM OPERATIONS	12,880	14,704
NON-OPERATING (EXPENSE) INCOME:
Interest income	39	3
Interest expense	(22,384)	(22,180)
Other, net	525	143
Total non-operating	(21,820)	(22,034)
(LOSS) INCOME BEFORE INCOME TAXES	(8,940)	(7,330)
(BENEFIT) PROVISION FOR INCOME TAXES	(2,250)	(2,189)
NET (LOSS) INCOME BEFORE EARNINGS OF CONSOLIDATED SUBSIDIARIES	(6,690)	(5,141)
Net (loss) income of consolidated subsidiaries	(527)	(338)
NET (LOSS) INCOME	(7,217)	(5,479)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
NET SALES	14,718	14,614
COST OF SALES (exclusive of amortization shown separately below)	8,967	9,627
GROSS PROFIT	5,751	4,987
OPERATING EXPENSES:
Research and development	4,019	4,214
Selling and marketing	2,545	2,695
Distribution	389	388
General and administrative	1,300	1,045
Amortization expense	1,069	1,076
Total operating expenses	9,322	9,418
INCOME (LOSS) FROM OPERATIONS	(3,571)	(4,431)
NON-OPERATING (EXPENSE) INCOME:
Interest expense	(118)	(123)
Other, net	(128)	(40)
Total non-operating	(246)	(163)
(LOSS) INCOME BEFORE INCOME TAXES	(3,817)	(4,594)
(BENEFIT) PROVISION FOR INCOME TAXES	(1,401)	(1,734)
NET (LOSS) INCOME BEFORE EARNINGS OF CONSOLIDATED SUBSIDIARIES	(2,416)	(2,860)
NET (LOSS) INCOME	(2,416)	(2,860)
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
NET SALES	35,299	39,573
COST OF SALES (exclusive of amortization shown separately below)	22,603	24,439
GROSS PROFIT	12,696	15,134
OPERATING EXPENSES:
Research and development	172	224
Selling and marketing	5,041	6,124
Distribution	1,587	1,972
General and administrative	2,158	2,578
Amortization expense	537	635
Total operating expenses	9,495	11,533
INCOME (LOSS) FROM OPERATIONS	3,201	3,601
NON-OPERATING (EXPENSE) INCOME:
Interest income	25	78
Interest expense	(12)	(20)
Other, net	(524)	(27)
Total non-operating	(511)	31
(LOSS) INCOME BEFORE INCOME TAXES	2,690	3,632
(BENEFIT) PROVISION FOR INCOME TAXES	801	1,110
NET (LOSS) INCOME BEFORE EARNINGS OF CONSOLIDATED SUBSIDIARIES	1,889	2,522
NET (LOSS) INCOME	$ 1,889	$ 2,522