IBM on Monday said it has developed a computer mouse that can help hand-tremor sufferers eliminate excessive cursor movements, which often prevents the elderly and others from using a computer.

IBM has licensed its mouse adapter to Montrose Secam Ltd., a small British electronics company that's selling the device for less than $100 through its website.

Uncontrollable tremors of the limbs, most often the hands, afflict about 10 million Americans, with 4 percent of them under the age of 60, according to the International Essential Tremor Foundation, based in Lenexa, Kan. The condition often starts at the age of 45.

Among the more famous sufferers of the condition was actress Katherine Hepburn, who had uncontrollable tremors of the head. Researchers do not know what causes the condition, and there's no cure.

"This is a significant problem," Catherine Rice, executive director of IETF, said. "There's going to be a huge demand for this (product)."

The "Assistive Mouse Adapter" sits between the mouse and computer and filters out shaking movements of the hand in a way that's similar to stabilization systems found in camcorders. The device, which is designed to work with any computer and operating system, does not require additional software and can be switched on or off. It also can be adjusted to the severity of the tremors, and can filter out unintended multiple clicking on the mouse caused by a shaking finger.

IBM researcher Jim Levine said he got the idea for the device a couple of years ago at an IBM workshop on the problems seniors have in using a computer. During the workshop, Levine remembered how his Uncle Murray Levine, who was 70 at the time, couldn't use a computer.

"My uncle was unable to use the computer because of too much hand tremor," Levine said. "I remembered that at the workshop, and I thought it would worthwhile to try to solve that problem."

Parkinson's is the disease most commonly associated with tremors, but other conditions, such as essential tremors, are more common, the IETF said. Essential tremor is an inherited condition that can affect people throughout their lives.

There are more than 750 million people with disabilities worldwide, with 54 million of them living in the United States, according to IBM, which sees the market as a significant business opportunity. IBM believes accessible-computing technologies will become mainstream among business customers.

According to Nielsen/NetRatings, senior citizens age 65 and older were the fastest growing age group online in 2003, increasing 25 percent year over year to 9.6 million.