Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of medical-device manufacturer Cyberonics (Nasdaq: CYBX) took flight today, rising more than 11% in intraday trading as investors reacted to the company's fiscal-second-quarter earnings.

So what: It's rare that a 50% drop in net income isn't a reason for investors to be seriously worried. But for Cyberonics, hefty tax benefits threw off both the recently completed quarter as well as the same quarter a year ago. Revenue and operating income for the company were actually up 17% and 41%, respectively, versus last year as the company's VNS Therapy System continued to show healthy gains in the U.S. market. Adjusted earnings per share of $0.26 slightly edged out the $0.25 expected by Wall Street analysts.

Now what: It was the look ahead, however, that likely got investors really jazzed about Cyberonics' report. After a better-than-expected first half of its fiscal year, the company decided to bump up its full-year guidance, taking the midpoint of its revenue forecast from $186 million to $188.5 million. Operating income expectations were boosted from a midpoint of $43.5 million to $46.5 million. The new operating profit guidance represents 26% growth over fiscal 2010's tally -- a growth rate the company will likely have to at least sustain to justify the stock's current valuation.

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy assures you no Wookiees were harmed in the making of this article.