CEREBRAL METABOLISM IN SLEEP-APNEA - EVALUATION BY MAGNETIC-RESONANCESPECTROSCOPY

Repeated apneic episodes during sleep may lead to cerebral damage in p atients with obstructive sleep apnea (OSA). We performed proton magnet ic resonance (MR) spectroscopic studies to examine cerebral metabolism in patients with OSA. We studied 15 healthy subjects and 23 patients with OSA who displayed no anatomical abnormalities on MR imaging, The patients were classified into two groups based on the results of polys omnography: mild OSA (11 patients) or moderate to severe OSA (12 patie nts). All the subjects were examined with two-dimensional chemical shi ft imaging. The N-acetylaspartate (NAA)/choline (Cho), NAA/creatine (C re), and Cho/Cre ratios for cerebral cortex and white matter were calc ulated separately, A statistically significant intergroup difference w as found for the NAA/Cho ratio in cerebral white matter (p < 0.005). T his ratio was significantly lower in patients with moderate to severe OSA than in patients with mild OSA (p < 0.01) and healthy subjects (p < 0.01). Our findings indicate that cerebral metabolic changes occur i n normal-appearing brain tissue in patients with moderate to severe OS A. The finding of a decreased NAA/Cho ratio suggests the presence of c erebral damage, probably caused by repeated apneic episodes. Proton MR spectroscopy may be useful for evaluating cerebral damage in patients with OSA.