The simple device seems to help patients overcome freezing episodes, where patients' legs literally freeze in place as they're trying to walk. For about 30 percent of Parkinson's patients, this "sudden transient freezing" is one of the most difficult symptoms of the disease. The episodes can last for seconds or even several minutes. Some patients experience only momentary hesitation occasionally, while for others the episodes occur dozens of times a day, making almost any simple movement from room to room a laborious task taking several minutes.

Patient Stan Clark of Old Forge, a small town in northern New York State, noticed that when his legs stopped, looking at patterns on the floor sometimes helped him start moving again. A retired glazier, Clark etched a line in his glasses so that when he looked down, he saw the line, which helped him begin walking again_but the line obscured his vision. Then he tried a flashlight, shining the beam at the spot he wanted to walk toward and trying to step on the spot. But the flashlight's beam spread out too much. Then Clark chanced upon a laser pointer. "I looked at the laser spot, and my feet just seemed to go to it," he says.

Clark talked about his experience with his doctors, neurologists Timothy Counihan and Lin Zhang, who then tried the device with six patients in the doctors' office. Three patients improved an average of 20 percent, while one other patient's freezing actually worsened, probably because she was concentrating so much on using the device, says Counihan. When a doctor assisted by shining the beam for her, that patient also improved markedly. Two other patients had no freezing episodes while walking back and forth for 30 feet.

"This is a very practical, inexpensive device that patients can carry with them," says Counihan. "It seems to get them moving again." Counihan points out that a larger study is necessary to check the initial findings.

While freezing episodes are impossible to predict, it often happens when patients move from one environment to another _ when they get on or off an elevator, get up from a chair, or move through a doorway. "For these patients, it's like their feet are stuck in wet cement, and currently there's no way to treat it," says Counihan.

Doctors don't know exactly what causes freezing in Parkinson's disease, which affects about 500,000 adults in the United States. The disease kills brain cells in a vital region of the brain known as the substantia nigra. This pea-sized part of the brain produces dopamine, a neurotransmitter that's key to the control of movement. The disease results in uncontrollable tremors and shaky, stiff, and slow movements. Sometimes, visual cues seem to bypass the diseased part of the brain and spur movement.

"This has been a very frustrating component of Parkinson's to try to treat," says neurologist and co-author Roger Kurlan. "We've known that visual cues can play a role in helping patients move, but there's never been a practical way to use that information."

Patients do try a variety of visual cues to get moving again, Counihan says. Some install tile floors, whose patterns help them navigate across a room more easily than a plain floor. Some patients put strips of tape on floors, then step toward the stripes. When freezing does happen, a few flip their cane, using the curved top as a guide to walk toward. "Using such cues is a way of tricking your brain to tell your body, `Step over there,'" says Counihan. "A laser pointer is an easy way to give yourself a visual cue."

Clark, for one, now carries a laser point faithfully. While such a device retails only for $10 or $15, "it gets pretty expensive buying batteries," he says, noting that his device takes three button batteries. It's also difficult to see the laser spot outdoors on sunny days. And Counihan says that a laser that emits a line instead of a spot might work even better.

"We can learn from our patients," says Counihan. "It's a brilliant idea. It's not a miracle cure, but for some patients it's the first thing that has really worked."

Note: If no author is given, the source is cited instead.

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