Thalamic activation in the Kleine-Levin syndrome.

STUDY OBJECTIVES

The objective of this study was to investigate if combined measures of activation in the thalamus and working memory capacity could guide the diagnosis of Kleine-Levin Syndrome (KLS). A second objective was to obtain more insight into the neurobiological causes of KLS.

DESIGN

Matched group and consecutive recruitment.

SETTING

University hospital neurology department and imaging center.

PATIENTS OR PARTICIPANTS

Eighteen patients with KLS diagnosed according to the International Classification of Sleep Disorders and 26 healthy controls were included.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Working memory capacity was assessed by the listening span task. A version of this task (reading span) was presented to the participants during functional magnetic resonance imaging (fMRI). Activation in the thalamus was measured in a region of interest analysis. A combination of the working memory capacity and the thalamic activation measures resulted in 80% prediction accuracy, 81% sensitivity, and 78% specificity regarding the ability to separate KLS patients from healthy controls. The controls had an inverse relation between working memory capacity and thalamic activation; higher performing participants had lower thalamic activation (r = -0.41). KLS patients showed the opposite relationship; higher performing participants had a tendency to higher thalamic activation (r = -0.35).

CONCLUSIONS

This study shows that functional neuroimaging of the thalamus combined with neuropsychological assessment of working memory function provides a means to guide diagnosis of Kleine-Levin Syndrome. Results in this study also indicate that imaging of brain function and evaluation of cognitive capacity can give insights into the neurobiological mechanisms of Kleine-Levin Syndrome.