A 1H magnetic resonance spectroscopy study in patients with obstructive sleep apnea.
OBJECTIVE
Repeated episodes of hypoxia, hypercapnia and transient blood pressure elevation in obstructive sleep apnea syndrome (OSAS) may damage neutral structures and induce cerebral metabolic impairment. This study aimed to determine the impact of OSAS on cerebral metabolites measured by (1)H magnetic resonance spectroscopy ((1)H -MRS).


METHODS
Twenty OSAS patients underwent standard overnight polysomnography and (1)H-MRS separately. Proton volumes of interest (VOIs) were placed in frontal and midtemporal regions bilaterally.


RESULTS
Significantly lower values of the N-acetylaspartate (NAA)/creatine (Cr) ratio were found in frontal regions (P < 0.004) compared with 20 age-matched control subjects. A significant increase in the myo-inositol (Ins)/Cr ratio was evident bilaterally in temporal and frontal regions (P < 0.00002 and P < 0.04). Choline (Cho)/Cr ratio values were also significantly greater in temporal regions (P < 0.00001). A significant negative correlation (r = -0.51, P < 0.03) was found between the apnea-hypopnea index (AHI) and NAA/Cr ratio in the frontal regions of OSAS patients.


CONCLUSIONS
Reduction in the NAA/Cr ratio in frontal regions of OSAS patients could be related to neural loss. Increase in the Cho/Cr ratio in temporal regions and Ins/Cr ratio in both frontal and temporal regions could be interpreted as evidence of membrane breakdown and reactive gliosis, respectively, consequent to repeated episodes of hypoxia in OSAS.
Sarchielli
P
P
Neurologic Clinic, University of Perugia, Perugia, Italy.
Presciutti
O
O
Alberti
A
A
Tarducci
R
R
Gobbi
G
G
Galletti
F
F
Costa
C
C
Eusebi
P
P
Calabresi
P
P
D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001923:Brain Chemistry; D016923:Cell Death; D002794:Choline / Q000032:analysis*; D015897:Comorbidity; D003404:Creatinine / Q000032:analysis*; D005260:Female; D005625:Frontal Lobe / Q000737:chemistry; D005911:Gliosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D002534:Hypoxia, Brain / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D007294:Inositol / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D013702:Temporal Lobe / Q000737:chemistry
D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003404:Creatinine; D002794:Choline