Departments of Medicine, All India Institute of Medical Sciences, New Delhi, India.
Indian J Med Res. 2010 Sep;132:278-86.
BACKGROUND & OBJECTIVES: Repeated apnoeic/hypoapnoeic episodes during sleep may produce cerebral damage in patients with obstructive sleep apnoea (OSA). The aim of this study was to determine the absolute concentration of cerebral metabolites in apnoeic and non-apnoeic subjects from different regions of the brain to monitor the regional variation of cerebral metabolites.
Absolute concentration of cerebral metabolites was determined by using early morning proton magnetic resonance spectroscopy ((1)H MRS) in 18 apnoeic patients with OSA (apnoeics) having apnoea/hypopnoea index (AHI) >5/h, while 32 were non-apnoeic subjects with AHI< 5/h.
The absolute concentration of tNAA [(N-acetylaspartate (NAA)+N-acetylaspartylglutamate (NAAG)] was observed to be statistically significantly lower (P<0.05) in apnoeics in the left temporal and left frontal gray regions compared to non-apnoeics. The Glx (glutamine, Gln + glutamate, Glu) resonance showed higher concentration (but not statistically significant) in the left temporal and left frontal regions of the brain in apnoeics compared to non-apnoeics. The absolute concentration of myo-inositol (mI) was significantly high (P<0.03) in apnoeics in the occipital region compared to non-apnoeics.
INTERPRETATION & CONCLUSIONS: Reduction in the absolute concentration of tNAA in apnoeics is suggestive of neuronal damage, probably caused by repeated apnoeic episodes in these patients. NAA showed negative correlation with AHI in the left frontal region, while Cho and mI were positively correlated in the occipital region and Glx showed positive correlation in the left temporal region of the brain. Overall, our results demonstrate that the variation in metabolites concentrations is not uniform across various regions of the brain studied in patients with OSA. Further studies with a large cohort of patients to substantiate these observations are required.
睡眠中反复出现的呼吸暂停/低通气事件可能导致阻塞性睡眠呼吸暂停（OSA）患者的脑损伤。本研究的目的是确定来自大脑不同区域的呼吸暂停和非呼吸暂停受试者的脑代谢物绝对浓度，以监测脑代谢物的区域变化。
使用清晨质子磁共振波谱（1H MRS）对 18 例呼吸暂停/低通气指数（AHI）>5/h 的 OSA 呼吸暂停患者（呼吸暂停组）和 32 例 AHI<5/h 的非呼吸暂停患者进行脑代谢物绝对浓度的测定。
与非呼吸暂停组相比，呼吸暂停组左侧颞叶和左侧额叶灰质区的 tNAA（N-乙酰天冬氨酸（NAA）+N-乙酰天门冬氨酸谷氨酸（NAAG））绝对浓度明显降低（P<0.05）。脑 Glx（谷氨酰胺、Gln+谷氨酸、Glu）共振在呼吸暂停组的左侧颞叶和左侧额叶脑区的浓度较高（但无统计学意义）。与非呼吸暂停组相比，呼吸暂停组枕叶区的肌醇（mI）绝对浓度显著升高（P<0.03）。
呼吸暂停患者 tNAA 的绝对浓度降低提示神经元损伤，可能是由于这些患者反复出现呼吸暂停事件所致。在左侧额叶区，NAA 与 AHI 呈负相关，而 Cho 和 mI 呈正相关，Glx 则在左侧颞叶区呈正相关。总的来说，我们的研究结果表明，在 OSA 患者的不同脑区，代谢物浓度的变化并不均匀。需要进一步进行更大规模的队列研究以证实这些观察结果。
