Regional cerebral blood flow alterations in obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA) is a condition characterized by upper airway muscle atonia with continued diaphragmatic efforts, resulting in repeated airway obstructions, periods of intermittent hypoxia, large thoracic pressure changes, and substantial shifts in arterial pressure with breathing cessation and resumption. The hypoxic exposure and hemodynamic changes likely induce the structural and functional deficits found in multiple brain areas, as shown by magnetic resonance imaging (MRI) procedures. Altered cerebral blood flow (CBF) may contribute to these localized deficits; thus, we examined regional CBF, using arterial spin labeling procedures, in 11 OSA (age, 49.1±12.2 years; 7 male) and 16 control subjects (42.3±10.2 years; 6 male) with a 3.0-Tesla MRI scanner. CBF maps were calculated, normalized to a common space, and regional CBF values across the brain quantified. Lowered CBF values emerged near multiple bilateral brain sites in OSA, including the corticospinal tracts, superior cerebellar peduncles, and pontocerebellar fibers. Lateralized, decreased CBF appeared near the left inferior cerebellar peduncles, left tapetum, left dorsal fornix/stria terminalis, right medial lemniscus, right red nucleus, right midbrain, and midline pons. Regional CBF values in OSA are significantly reduced in major sensory and motor fiber systems and motor regulatory sites, especially in structures mediating motor coordination; those reductions are often lateralized. The asymmetric CBF declines in motor regulatory areas may contribute to loss of coordination between upper airway and diaphragmatic musculature, and lead to further damage in the syndrome.

Keywords: ASL; Arterial spin labeling; CBF; Cerebral hemodynamics; EPI; FA; FOV; Hypoxemia; MRI; Motor coordination; OSA; Sensory control; TE; TR; arterial spin labeling; cerebral blood flow; echo-planner-imaging; echo-time; field of view; flip-angle; magnetic resonance imaging; obstructive sleep apnea; repetition time.

Conflict of interest statement

Conflict of interest:

All authors have no conflict of interest to declare.

Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Figures

Fig. 1

(A) Regions of interest (ROIs) from different brain sites, overlaid onto T1-weighted images that showed significant bilateral and unilateral reduction of CBF in OSA. The bilateral areas included the corticospinal tracts (coronal; a, b), superior cerebellar peduncles (coronal; c, d), pontocerebellar fibers (coronal; e, f), and regions of unilateral CBF reduction, which included the right medial lemniscus (coronal; g), right red nucleus (axial; h), left tapetum (coronal; i), left dorsal fornix/stria terminalis (sagittal; j), left inferior cerebellar peduncle (coronal; k), midline pons (coronal; l), and right midbrain (coronal; m). All brain images are displayed in neurological convention, with the left side of brain represented on the left side of the image. (L = Left, R = right). (B) Examples of whole-brain CBF maps in an OSA (age, 55.7 years; male), and a control subject (age, 54.9 years; male). Warm colors indicate corresponding regional CBF values.