On the relation between self-reported cognitive fatigue and the posterior hypothalamic-brainstem network.
BACKGROUND AND PURPOSE
Various causes have been suggested for multiple sclerosis (MS) related fatigue. Hypothalamus-brainstem fibres play a role in sleep-wake regulation and in hypothalamic deactivation during inflammatory states. Hence, they may play a role for experiencing fatigue by changing bottom-up hypothalamic activation.


METHODS
Multiple sclerosis patients with and without self-reported cognitive fatigue and healthy controls were analysed with respect to the integrity of hypothalamus-brainstem fibres using diffusion-tensor imaging based tractography, focusing on the anterior, medial and posterior hypothalamic areas, controlling for clinical impairment and excluding participants with depressive mood.


RESULTS
Multiple sclerosis patients without self-reported cognitive fatigue showed increased axial and radial diffusivity levels specifically for fibres connecting the right posterior hypothalamus with the right locus coeruleus, but not for the medial hypothalamus and the corpus callosum. Moreover, there were no differences between MS patients with and without fatigue in brain atrophy and lesion load, which could explain our results.


CONCLUSION
Multiple sclerosis patients not experiencing fatigue show increased axial and radial diffusivity for fibres connecting the posterior hypothalamus and the brainstem, which might prevent bottom-up activation of the posterior hypothalamus and therefore downregulation of structures responsible for wakefulness and exploratory states of mind.
['Hanken|K|K|', 'Manousi|A|A|', 'Klein|J|J|', 'Kastrup|A|A|', 'Eling|P|P|', 'Hildebrandt|H|H|']
D000328:Adult D001933:Brain Stem D056324:Diffusion Tensor Imaging D005260:Female D006801:Humans D007031:Hypothalamus D008297:Male D005222:Mental Fatigue D008875:Middle Aged D009103:Multiple Sclerosis D009415:Nerve Net D057566:Self Report
fatigue multiple sclerosis hypothalamus brainstem MRI diffusion tensor imaging