Neuroimaging Insights into the Pathophysiology of Sleep Disorders

Abstract

Neuroimaging methods can be used to investigate whether sleep disorders are associated with specific changes in brain structure or regional activity. However, it is still unclear how these new data might improve our understanding of the pathophysiology underlying adult sleep disorders. Here we review functional brain imaging findings in major intrinsic sleep disorders (i.e., idiopathic insomnia, narcolepsy, and obstructive sleep apnea) and in abnormal motor behavior during sleep (i.e., periodic limb movement disorder and REM sleep behavior disorder). The studies reviewed include neuroanatomical assessments (voxel-based morphometry, magnetic resonance spectroscopy), metabolic/functional investigations (positron emission tomography, single photon emission computed tomography, functional magnetic resonance imaging), and ligand marker measurements. Based on the current state of the research, we suggest that brain imaging is a useful approach to assess the structural and functional correlates of sleep impairments as well as better understand the cerebral consequences of various therapeutic approaches. Modem neuroimaging techniques therefore provide a valuable tool to gain insight into possible pathophysiological mechanisms of sleep disorders in adult humans.

Midlife migraine and late-life parkinsonism

“…[30][31][32][33] Iron deposition may itself be pathogenic, a marker of tissue damage due to other processes, or a reversible epiphenomenon. 7,28,31 If the increased iron deposition observed in migraineurs in these few studies reflects (directly or indirectly) neuronal damage, this would be consistent with the late-life symptoms observed in our study population.…”

Impact of obstructive sleep apnea on cognitive performance

“…Despite that researchers still fail to reach a consensus on the issue EDS versus neuronal damage, the mere possibility of irreversible brain damage associated with a highly prevalent and often underestimated medical problem is an alarming feature. The latest observations on neuronal death associated with intermittent hypoxia in animal models of OSA and functional neuroimaging studies in humans help to understand the nature of injuries, leading to speculation about strategies to halt or even to reverse this process 26,27 . A better understanding of the mechanisms of neuronal dysfunction or cell death that may occur in OSA might bring benefits to these patients.…”

The Sleeping Cerebellum

“…Patients suffering from primary sleep disorders such as chronic insomnia, fatal familial insomnia, or obstructive sleep apnea accompanied by daytime sleepiness [65] show a decreased cerebellar volume [11,66]. Likewise, patients with REM sleep behavior disorder, which generates dream-enacting motor activity during REM, show a volumetric decrement in the anterior lobes of the cerebellar cortex and cerebellar nuclei [67,68].…”