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Kumar R, Pham TT, Macey PM, Woo MA, Yan-Go FL, Harper RM. Abnormal myelin and axonal integrity in recently diagnosed patients with obstructive sleep apnea. Sleep 2014; 37:723-32. [PMID: 24899761 DOI: 10.5665/sleep.3578] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Patients with obstructive sleep apnea (OSA) show significant white matter injury; whether that injury represents myelin or axonal damage is unclear. The objective was to examine myelin and axonal changes in patients with newly diagnosed OSA over control subjects. DESIGN Cross-sectional study. SETTING University-based medical center. PARTICIPANTS Twenty-three newly-diagnosed, treatment-naïve OSA and 23 age- and sex-matched control subjects. INTERVENTIONS None. MEASUREMENTS AND RESULTS Radial and axial diffusivity maps, calculated from diffusion tensor imaging data (3.0 Tesla MRI scanner), indicating diffusion perpendicular (myelin status) or parallel (axonal status) to fibers, respectively, were normalized, smoothed, and compared between groups (analysis of covariance; covariate: age). Global brain radial and axial diffusivity values, and global brain volume with myelin and axonal changes were determined, and region-of-interest analyses performed in areas of significant differences between groups based on voxel-based procedures. Global radial and axial diffusivity values were significantly reduced in OSA versus control subjects (radial, P = 0.004; axial, P = 0.019), with radial (myelin) diffusivity reduced more than axial (axonal), and more left-sided reduction for both measures. Localized declines for myelin and axonal measures appeared in the dorsal and ventral medulla, cerebellar cortex and deep nuclei, basal ganglia, hippocampus, amygdala, corpus callosum, insula, cingulate and medial frontal cortices, and other cortical areas (P < 0.005), all regions mediating functions affected in OSA. CONCLUSIONS Fiber injury appears in critical medullary respiratory regulatory sites, as well as cognitive and autonomic control areas. Myelin is more affected in newly diagnosed OSA than axons, and primarily on the left side, possibly from the increased myelin sensitivity to hypoxia and asymmetric perfusion.
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Affiliation(s)
- Rajesh Kumar
- Department of Anesthesiology ; Department of Radiological Sciences ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA
| | - Tiffany T Pham
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Paul M Macey
- UCLA School of Nursing, Los Angeles, CA ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA
| | | | - Frisca L Yan-Go
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Ronald M Harper
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA
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Kumar R, Farahvar S, Ogren JA, Macey PM, Thompson PM, Woo MA, Yan-Go FL, Harper RM. Brain putamen volume changes in newly-diagnosed patients with obstructive sleep apnea. NEUROIMAGE-CLINICAL 2014; 4:383-91. [PMID: 24567910 PMCID: PMC3930100 DOI: 10.1016/j.nicl.2014.01.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 01/17/2014] [Accepted: 01/21/2014] [Indexed: 11/24/2022]
Abstract
Obstructive sleep apnea (OSA) is accompanied by cognitive, motor, autonomic, learning, and affective abnormalities. The putamen serves several of these functions, especially motor and autonomic behaviors, but whether global and specific sub-regions of that structure are damaged is unclear. We assessed global and regional putamen volumes in 43 recently-diagnosed, treatment-naïve OSA (age, 46.4 ± 8.8 years; 31 male) and 61 control subjects (47.6 ± 8.8 years; 39 male) using high-resolution T1-weighted images collected with a 3.0-Tesla MRI scanner. Global putamen volumes were calculated, and group differences evaluated with independent samples t-tests, as well as with analysis of covariance (covariates; age, gender, and total intracranial volume). Regional differences between groups were visualized with 3D surface morphometry-based group ratio maps. OSA subjects showed significantly higher global putamen volumes, relative to controls. Regional analyses showed putamen areas with increased and decreased tissue volumes in OSA relative to control subjects, including increases in caudal, mid-dorsal, mid-ventral portions, and ventral regions, while areas with decreased volumes appeared in rostral, mid-dorsal, medial-caudal, and mid-ventral sites. Global putamen volumes were significantly higher in the OSA subjects, but local sites showed both higher and lower volumes. The appearance of localized volume alterations points to differential hypoxic or perfusion action on glia and other tissues within the structure, and may reflect a stage in progression of injury in these newly-diagnosed patients toward the overall volume loss found in patients with chronic OSA. The regional changes may underlie some of the specific deficits in motor, autonomic, and neuropsychologic functions in OSA. Global and regional putamen volumes were examined in newly-diagnosed OSA. Global volumes are higher, but subareas showed increases and decreases. The volume increases suggest transient tissue swelling from hypoxic action. Altered sites likely contribute to motor and other functional deficits in OSA.
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Key Words
- 3D surface morphometry
- 3D, Three dimensional
- AHI, Apnea–hypopnea index
- Autonomic
- BAI, Beck Anxiety Inventory
- BDI-II, Beck Depression Inventory II
- Basal ganglia
- CSF, Cerebrospinal fluid
- Cognition
- ESS, Epworth Sleepiness Scale
- FA, Flip angle
- FOV, Field of view
- GRAPPA, Generalized autocalibrating partially parallel acquisition
- Intermittent hypoxia
- MNI, Montreal Neurological Institute
- MPRAGE, Magnetization prepared rapid acquisition gradient-echo
- MRI, Magnetic resonance imaging
- Magnetic resonance imaging
- Motor
- OSA, Obstructive sleep apnea
- PD, Proton density
- PSQI, Pittsburgh Sleep Quality Index
- TE, Echo time
- TIV, Total intracranial volume
- TR, Repetition time
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Affiliation(s)
- Rajesh Kumar
- Department of Anesthesiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA ; Department of Radiological Sciences, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Salar Farahvar
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Jennifer A Ogren
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Paul M Macey
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, USA ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Paul M Thompson
- Department of Neurology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA ; Department of Psychiatry, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Mary A Woo
- UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Frisca L Yan-Go
- Department of Neurology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Ronald M Harper
- Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA ; The Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA
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Abstract
In cases with suspected brain anoxia/ischemia and hypoxia/hypoxemia a neuropathological investigation should give additional information to elucidate the cause of death and its pathophysiological mechanisms. Primary ischemic brain damage is associated with morphological and biochemical alterations. While acute ischemic neuronal injury reveals axon sparing and selective neuronal lesions due to the release of large quantities of glutamate, late neuronal death is associated with antiapoptotic growth factors, and decreased expression of microtubule-associated proteins and tubulin. On the morphological level ischemia can be detected by necrosis of neurons, proliferation of microglia, and astrocytes in vulnerable regions of the brain. In cases of permanent ischemia the so-called pale nervous cell injury is observed, in cases of partial perfusion the so-called dark nerve cell injury and apoptosis are detectable. In spite of the considerable advantages of recent research, presently there is no reliable qualitative marker to ascertain death due to acute hypoxic or ischemic events.
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Affiliation(s)
- Manfred Oechmichen
- Insitute of Legal Medicine, University of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 12, D-24105 Kiel, Germany.
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Oehmichen M, Meissner C, von Wurmb-Schwark N, Schwark T. Methodical approach to brain hypoxia/ischemia as a fundamental problem in forensic neuropathology. Leg Med (Tokyo) 2003; 5:190-201. [PMID: 14602162 DOI: 10.1016/s1344-6223(03)00077-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A review is given summarizing different methods that have been applied to the specific forensic neuropathological question of brain hypoxia/ischemia. On the microscopic level the authors applied routine stains and immunohistochemistry (MAP2, ALZ 50, GFAP, CD68, beta-APP) for characterization of the functional activity of neurons as well as of different cell types in various brain areas. Moreover, using molecular techniques for evaluation of the mitochondrial 4977-bp deletion in correlation to hypoxia and to age brain tissue and single cell analyses are described. The demonstrated scope of methods and results give evidence of the wide spectrum of possibilities to visualize hypoxic brain injuries for determining the cause (and matter) of death and for reconstructing the time-dependent process.
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Affiliation(s)
- Manfred Oehmichen
- Institute of Forensic Medicine, University Hospital of Schleswig-Holstein, Campus Lübeck, Kahlhorststrasse 31-35, D-23562 Lübeck, Germany.
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