Employment lawyers are warning companies they could face liability or workers' compensation claims related to employee injuries from personal digital assistants.

The American Physical Therapy Association in Alexandria, Va., and other occupational organizations warn that improper use and overuse of personal digital assistants can lead to hand throbbing, tendonitis and swelling, a condition known as BlackBerry Thumb, named after the popular PDA.

"If you develop full-blown symptoms, it's pretty severe," says Alan Hedge, an ergonomics professor at Cornell University in Ithaca, N.Y. "Employers can train people how to correctly hold and use the handheld device and encourage employees to write brief e-mails."

Frank Morris, a lawyer in Washington, D.C., says employers need to develop policies on PDA use. They also face a liability risk because some employees could argue they're entitled to overtime if expected to use a company-provided PDA after work hours.

Some hotels catering to business clients offer treatments for the problem. The Hyatt Regency Scottsdale Resort and Spa in Scottsdale, Ariz., offers a special BlackBerry Balm Hand Massage that runs $80 for 30 minutes. A resort spokeswoman says the treatment has become very popular.

The new Sofitel Los Angeles hotel will offer a hand massage that releases tension caused by excessive use of PDAs at their full-service spa, set to open this month.

Some workers complain about ailments from severe tendonitis to general soreness. Jennifer Lane, 39, owner of financial planning company Compass Planning Associates in Boston, bought a PDA about six months ago and now says her right hand is "killing me."

"You get to the point you can't move your wrist anymore," says Lane, who says she is trying to limit e-mail length on her Treo. "I go on these marathon e-mail sessions."

Jay Winuk, 48, of Winuk Communications in Carmel, N.Y., says he experienced a thumb injury from using a PDA's click wheel. He was able to heal with treatment and by changing his behavior.

"I'm much more cautious about how I use it," Winuk says. "It's not as glamorous as breaking your leg, but it's just as much of a detriment."

Thumb injuries related to BlackBerrys, Treos and Sidekicks are occurring in part because employees who rely on the technology also use them extensively beyond normal working hours. Treatment can involve surgery, forgoing use of PDAs and physical therapy, says Stacey Doyon, president-elect of the Chicago-based American Society of Hand Therapists.

"I've seen people use them for hours on end. You're really stressing the fingers," Doyon says.

"In the workplace, you should dock them into a regular-size keyboard and monitor."

Research has found that some young people, dubbed the thumb generation, are adapting by using the thumb more as an index finger.

"I don't think people have been given a practical way to deal with this," says Sophie Wong, a creative director at Faith Popcorn's BrainReserve, a trend-based marketing consultant in New York. "This is going to be the common headache in the future."