SAN FRANCISCO - Google CEO Larry Page has disclosed a problem with his vocal cords that makes it difficult for him to speak and breathe occasionally, but he says he remains fit enough to keep running the Internet's most influential company.

The explanation that Page posted Tuesday on his Google Plus profile cleared up a mystery hanging over him since he lost his voice a year ago, causing him to miss Google Inc.'s annual shareholders meeting in June and a conference call to discuss the company's quarterly earnings in July.

Larry Page, 40, the company's co-founder and CEO for the past two years, says his left vocal cord has been paralyzed since coming down with a severe cold 14 years ago, while Google was still in its formative stages. That issue was compounded last year with another cold that Page says impaired his right vocal cord, though it still has limited movement.

Page's unavailability last year spooked investors, especially those who remembered Apple Inc.'s initial refusal to disclose the extent of co-founder Steve Jobs' health problems. Jobs took two formal medical leaves as Apple's CEO before resigning from the job about six weeks before his death from cancer. When Page had his health issue, Google had simply said Page was dealing with a throat problem that wouldn't get in the way of his job.

Wall Street's worries about Page's condition eased when he resurfaced in October to field questions during Google's earnings call. Although his voice has been raspy and robotic-sounding at times, Page has spoken at length in each of Google's three earnings calls since the one he missed.

Page provided further reassurance in Tuesday's post.

"Thankfully, after some initial recovery I'm fully able to do all I need to at home and at work, though my voice is softer than before," he wrote.

Doctors have not been able to diagnose why his vocal cords are hobbled, according to Page. The trouble could be tied to another health problem, Hashimoto's thyroiditis. Page said he was diagnosed with that condition in 2003. He described it as a "fairly common benign inflammatory condition of the thyroid which causes me no problems."

The weakened vocal cords affect more than just Page's voice. "Vocal cord nerve issues can also affect your breathing, so my ability to exercise at peak aerobic capacity is somewhat reduced," Page wrote. "That said, my friends still think I have way more stamina than them when we go kitesurfing!"

Page said doctors had told him his condition was "extremely rare."

Google said the company had no further comment beyond Page's post.

Investors seemed unfazed. After hitting a new all-time high of $888.69 Tuesday, Google's stock was still up by $9.57, or 1.1 percent, to close at $887.10. The shares have risen by 50 percent since Page replaced Eric Schmidt as Google's CEO in April 2011.

"It's a good thing that he is in good health, to a large extent," said Standard & Poor's Capital IQ analyst Scott Kessler. "It's unfortunate that he is in a position where he felt compelled to disclose these personal details, though I applaud him for his transparency. I completely understand why shareholders would want to know - and deserve to know - about the well-being of a key person in a business that they are investing in."

Page made his revelations on the eve of another major Google event - a conference for engineers and entrepreneurs who create software applications. It's not clear whether Page will make an onstage appearance this year after skipping last year's conference while he tried to regain his voice. Page, who isn't as outgoing as fellow Google co-founder Sergey Brin, had bypassed this conference in previous years, too.

The timing of Page's disclosures appeared tied to his decision to finance research into vocal cord paralysis at the Voice Institute. Page, whose owns Google stock worth about $22 billion, didn't disclose the size of his donation to the Voice Institute. He said it was large enough to support a "significant" research program that will be led by Dr. Steven Zeitels from the Harvard Medical School and the Massachusetts General Hospital Voice Center.

The amount of Page's contribution is believed to be in the tens of millions of dollars.