Summary of Significant Accounting Policies and Related Data (Details)	12 Months Ended				12 Months Ended
	Apr. 26, 2013 USD ($) item	Apr. 27, 2012 USD ($)	Dec. 17, 2007 USD ($)	Apr. 27, 2012 Foreign [Member] EUR (€)	Apr. 26, 2013 Property and Equipment [Member]	Apr. 26, 2013 Building [Member]	Apr. 26, 2013 Maximum [Member]	Apr. 26, 2013 Minimum [Member]
Number of countries VNS Therapy System is approved to be marketed in (in Countries)	72
Number of patients implanted with VNS Therapy System (in Patients)	82,000
Minimum age requirement for treatment under VNS Therapy System (in Years)	18
Minimum number of treatments with no response, required to receive VNS Therapy (in Treatments)	4
Percent of patient population	0.20%
Property, plant and equipment, estimated useful lives (in Years)					3 to 9	39
Acquisition of land and building, purchase price		$ 11,700,000
Upfront payment received under license agreement			9,500,000
Deferred revenue, unamortized	1,467,869	2,961,837
Medical devices sold domestically, excise tax rate (in Percent)	2.30%
Medical Device Excise Tax reported in cost of good sold	1,200,000
Share-based compensation arrangement by share-based payment award, award requisite service period (in Duration)							5 years	4 years
Share-based compensation arrangement by share-based payment award, award cliff-vesting period (in Duration)							3 years	1 year
Share-based compensation arrangement by share based-payment award, maximum term of award (in Duration)	10 years
Share-based compensation arrangement by share-based payment award, shares to be repurchased next year	58,819
Deferred compensation plan, percent of base salary compensation eligible for deferral (in Percent)	50.00%
Deferred compensation plan percent of bonus or performance-based compensation eligible for deferral (in Percent)	100.00%
Net operating loss carryforwards				€ 25.7