Google CEO Larry Page was diagnosed with vocal chord paralysis.  He hasn't spoken much lately, and now the reasons are clear: a rare disease.

Larry Page, 40, said in a post on the Google+ social networking service that he has a "very rare" case of vocal-chord paralysis. He contracted the problem after having a bad cold 14 years ago. One of his vocal chords became paralyzed and never recovered. Doctors haven't been able to figure out why.

Last year, another cold brought problems to his second vocal chord. But since then, Mr. Page said his condition is a bit better.

Many have expressed concern over Larry Page's health. He mysteriously was absent during Google's annual shareholder meeting in June and various other important events. He said he'd "lost his voice", but he continued to run the company. Wall Street investors and other execs were in a tizzy of swirling rumors, worrying he might have had a deadly medical problem.

In a previous email, Mr. Page told Google employes that there was "nothing seriously wrong with me." But still, his voice sounded weak and hoarse during phone calls and meetings.

Tomorrow Google's annual conference in San Francisco for software developers who create applications will begin. Analysts have dubbed his disclosure a smart move and responsible to investors. Jeffrey Sonnenfeld, a senior associate dean at Yale School of Management, called the act "in sharp contrast with [former Apple CEO] Steve Jobs's denials and efforts to disguise the truth for a fair bit of time."

Jobs died in 2011 at 56 of pancreatic cancer. He was reticent to share details of his condition, garnering flack at times.

Larry Page said in his statement,  "I'm fully able to do all I need to at home and at work, though my voice is softer than before." And, he said jokingly, Sergey Brin, fellow Google co-founder, "says I'm probably a better CEO because I choose my words more carefully."

Vocal chord paralysis is caused when one or both vocal chords don't open and close correctly. Mr. Page may, in time, see continued improvement.