Islamabad - Stroke is a leading cause of disability with loss of speech being one of its many devastating effects. For years, some scientists have claimed the right hemisphere of the brain interferes with speech recovery following stroke in the left hemisphere; but according to a new study.
The researcher found that the right side of the brain increases growth of gray matter to compensate for loss of gray matter in speech-related areas in the left side due to stroke, which can aid speech recovery.
The effects of stroke depend on how much brain tissue is affected and in what part of the brain it occurs. For example, if stroke occurs in the right side of the brain, this may lead to problems such as vision loss and paralysis on the left side of the body. If stroke occurs in the left side of the brain, this may lead to paralysis on the right side of the body and speech and language problems. Around a third of people who survive a stroke experience loss of speech, known as aphasia, and this almost always occurs in those who have experienced left-hemisphere strokes; around 70% of left-hemisphere stroke survivors have language problems.
Some individuals who experience speech loss after stroke may recover gradually in subsequent months, although most never fully recover. Over the past decade, studies have suggested the right side of the brain impairs the speech recovery process; the GUMC team set out to investigate this theory further.
What is more, the researchers found that stroke survivors with better-than-expected speech abilities also had larger gray matter volume in the right hemisphere of the brain than control participants.
According to the investigators, these findings indicate that growth of gray matter in the right hemisphere of the brain compensates for loss of gray matter in the left hemisphere to improve speech.
Dr Turkeltaub said that “Over the past decade, researchers have increasingly suggested that the right hemisphere interferes with good recovery of language after left hemisphere strokes. Our results suggest the opposite - that right hemisphere compensation improves recovery.”
The team notes that the area in the right hemisphere of the brain they identified only aids in use of speech, not understanding of speech. As such, the team plans to conduct further research to determine whether there are other areas of the right hemisphere that may compensate for speech comprehension.
The researchers hope their findings pave the way to new treatments for individuals who experience loss of speech after stroke.
Sleepwalkers ‘feel no pain’
in accidents
Although sleepwalkers have an increased risk for headaches and migraines when awake, while sleepwalking, they are unlikely to feel pain even after suffering an injury. The researchers said that Sleepwalkers reported headaches four times more frequently than non-sleepwalkers, and migraines 10 times more often, as well as higher levels of chronic pain, daytime sleepiness, and depressive and insomnia symptoms. After adjustments, however, sleepwalking was associated with increased risk for headache and migraine only. But most surprising was the assessment of pain perception during injuries sustained while asleep. Of the sleepwalkers, 47 reported having experienced at least one injurious sleepwalking episode. Only 10 reported waking immediately due to pain; the other 37 perceived no pain during the episode but felt pain later in the night or in the morning.
One patient sustained severe fractures after jumping out of a third-floor window while sleepwalking but did not feel the pain until after waking up later in the night.
Another broke his leg during a sleepwalking episode in which he climbed onto the roof of his house and fell down, but he did not wake up until morning.
Dr. Lopez said that “Our most surprising result was the lack of pain perception during the sleepwalking episodes. We report here, for the first time, an analgesia phenomenon associated with sleepwalking.”
He adds that, while the relationship between sleep and pain remains unclear, the results may help to understand why sleepwalking happens.
Regarding what causes sleepwalking, he says that many patients report “some disturbance that compels movement.” Howell suggests that sleepwalking could be related to motor restlessness, like restless leg syndrome.
Limitations of the study include the fact that sleepwalking episodes are generally associated with lack of conscious awareness and memory of the event; the absence of perceived pain during parasomnia episodes could be due to a recall bias.