FRIDAY, Sept. 10, 2004 (HealthDayNews) -- Along with the potentially devastating physical damage that a stroke can cause, a little known and rare consequence can be the loss of dreaming.
In the September issue of the Annals of Neurology, Swiss researchers report the case of an elderly woman who had a stroke and several days later stopped dreaming.
"This suggests that the area that was damaged [during the woman's stroke] probably has some important role to play in the complex process that gives rise to dreaming," said study author Dr. Claudio Bassetti, of the department of Neurology at University Hospital in Zurich.
Each year, about 700,000 Americans suffer a stroke, according to the American Stroke Association. Stroke is the third-leading cause of death in the United States and a major cause of disability.
While loss of dreaming after stroke-induced damage to the brain rarely occurs, the phenomenon was identified as early as the 1880s and is called Charcot-Wilbrand syndrome -- after the doctors who discovered it.
In the new study, a 73-year-old woman had suffered a stroke that blocked blood flow to a small area in the back of her brain. Using magnetic resonance imaging (MRI), the researchers found that both deep occipital lobes and the right posterolateral thalamus were affected by the stroke. These areas of the brain are involved in processing visual information and emotions, the researchers said.
Initially, the woman had vision loss and weakness on the left side of her body. Her vision improved within two days, but the weakness persisted throughout her four-week hospital stay.
During the third night after her stroke, the woman reported having a short but vivid dream. After that, she stopped dreaming altogether. Before her stroke, the woman reported she could recall her dreams three to four times a week.
Bassetti said it's difficult to know whether the woman stopped dreaming, or simply lost the ability to recall her dreams.
"My educated guess is to say she's not dreaming," he said.
To try to figure out whether it was a loss of dreaming or a loss of memory, Bassetti and his colleagues performed sleep studies on the woman at five days, and then three, four and six weeks after her stroke.
The sleep studies measured the woman's brain waves as she slept, and the researchers found she had normal sleep patterns and entered into rapid-eye-movement (REM) sleep.
While the mechanisms behind dreaming and REM sleep are thought to be different, dreaming occurs during REM sleep. The researchers woke the woman during REM sleep cycles because dream recall is often more vivid if you're awakened during a dream. But she still could not recall having a dream.
"Usually you can recall some dream experiences when woken up from REM sleep, which suggests she was closer to not dreaming" than to not being able to recall her dreams, Bassetti said.
Dr. Orrin Devinsky, a neurologist at New York University Medical Center, said, "Dreaming is very much a biological function, and like all behavior we manifest as people, it is served by areas or networks in the brain."
"Since even in REM she did not recall her dreams, it does suggest that those areas damaged were critical for either generating dreams or for recalling dreams," Devinsky said.
Eventually, the woman did begin dreaming again. She reported having about one dream a week a year after the stroke, though she said they were less vivid than her previous dreams.
More information
To learn more about stroke, visit the National Institute of Neurological Disorders and Stroke.
