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Nocturnal Limb Movements Linked to Impaired Cognitive Function

Nocturnal limb movements, which may lead to white matter hyperintensities, could be a potential vascular risk factor.


 

NEW ORLEANS—Nocturnal limb movements that are associated with poor sleep quality may contribute to cerebral white matter hyperintensities and could impair fronto-executive function, according to research presented at the 64th Annual Meeting of the American Academy of Neurology.

“Nocturnal limb movement counts strongly correlated with the presence of white matter hyperintensities, while sleep efficiency was negatively correlated with white matter hyperintensities,” stated study authors Mark I. Boulos, MD, a neurologist, and Brian Murray, MD, Associate Professor of Neurology and Sleep Medicine, both at Sunnybrook Health Sciences Centre in Toronto.

The researchers used polysomnography to assess 45 patients (69% male; mean age, 64) for sleep problems in a tertiary care behavioral neurology clinic. Patients’ white matter hyperintensity was rated with the Age Related White Matter Changes (ARWMC) score from fluid attenuated inversion recovery (FLAIR) MRI.

The study’s results showed a mean ARWMC score of 3.84 (range, 0 to 25), and the investigators found no differences in ARWMC scores between left and right brain hemispheres, though more limb movements were observed on the left side of the body (66.3), compared with the right side of the body (24.1). “This appears to be a fundamental asymmetry, much like handedness,” commented Dr. Murray.

After the researchers controlled for hypertension, total ARWMC scores were negatively correlated with sleep efficiency (r = –0.72) and positively correlated with total limb movements (r = 0.698) and total periodic limb movements (r = 0.544) per hour of sleep. Total periodic limb movements were negatively correlated with scores on the Trail Making A Test (r = –0.527), and this correlation remained even after controlling for age (r = –0.670), indicating difficulties with cognitive processing, said Dr. Murray.

“One can argue that limb movements give rise to white matter hyperintensities,” Dr. Murray told Neurology Reviews. “If this is the case, then limb movements can be considered a vascular risk factor, much like high blood pressure, diabetes, hyperlipidemia, etc, which are also associated with the development of white matter hyperintensities.

“Another way of looking at the findings is that white matter hyperintensities—that is, covert cerebrovascular disease—may cause limb movements in sleep. A few reports in the literature describe the development of nocturnal limb movements after clinically significant strokes. However, we are not aware of any reports describing white matter hyperintensities giving rise to nocturnal limb movements.”


—Lauren LeBano

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