* Efficacy improved at all dosing levels: study
* Shares up as much as 7 pct
May 27 (Reuters) - Medical-device maker Cyberonics Inc CYBX.O said its therapy for depression showed continued efficacy in a post-market dosing study.
In July 2005, The U.S. Food and Drug Administration had approved Cyberonic's Vagus Nerve Stimulation therapy for treatment-resistant depression, asking the company to conduct a long-term post-marketing study.
In the study, 32 percent to 42 percent of the patients showed redution in symptoms of depression after 50 weeks, when given electronic impulses in high, medium and low levels, the company said in a statement.
Shares of the company were up 3 percent at $17.99 in morning trade Thursday on Nasdaq. They had touched a high of $18.60 earlier in the session. (Reporting by Shailesh Kuber in Bangalore;)