Sex-Related Differences in the Interhemispheric Asymmetry of Cerebral Energy Metabolism in Young People Living in the Arctic Zone of the Russian Federation

In the Arctic region, adaptive reactions of the body put pressure on its functional systems and are accompanied by changes in cerebral energy metabolism in the central nervous system. Despite the fact that patterns of interhemispheric asymmetry and interaction are part of the brain’s essential, fundamental mechanism, no data is currently available on the neurometabolic features of interhemispheric asymmetry in men and women living in the Arctic zone of the Russian Federation. The aim of this paper was to identify the differences in cerebral energy metabolism in men and women born and living in the Arctic zone of the Russian Federation with different types of interhemispheric asymmetry according to the distribution of DC-potential level. Materials and methods. The study involved 63 subjects (30 men and 33 women) aged 30–34 years born and living in Arkhangelsk. Cerebral energy metabolism was assessed using the 5-channel Neuro-KM hardware and software complex. Distribution of DC-potential level was analysed by mapping the monopolar values and calculating their gradients. To calculate interhemispheric asymmetry of cerebral energy metabolism, an interhemispheric gradient was used, i.e. the potential difference between the right and left temporal leads (Td-Ts). The obtained DC-potential level results were compared with average standard values. The results of the study indicate differences in the distribution of the processes of cerebral energy metabolism in men and women with different types of hemispheric dominance. The most balanced cerebral metabolism was identified in men with right hemisphere dominance and in women with left hemisphere dominance. The presence of sex-related differences in the hemispheric asymmetry of cerebral energy metabolism may reflect different strategies of adaptation to the climatic conditions of northern latitudes in men and women.

Arterial Oxygenation in Traumatic Brain Injury—Relation to Cerebral Energy Metabolism, Autoregulation, and Clinical Outcome

Background: Ischemic and hypoxic secondary brain insults are common and detrimental in traumatic brain injury (TBI). Treatment aims to maintain an adequate cerebral blood flow with sufficient arterial oxygen content. It has been suggested that arterial hyperoxia may be beneficial to the injured brain to compensate for cerebral ischemia, overcome diffusion barriers, and improve mitochondrial function. In this study, we investigated the relation between arterial oxygen levels and cerebral energy metabolism, pressure autoregulation, and clinical outcome. Methods: This retrospective study was based on 115 patients with severe TBI treated in the neurointensive care unit, Uppsala university hospital, Sweden, 2008 to 2018. Data from cerebral microdialysis (MD), arterial blood gases, hemodynamics, and intracranial pressure were analyzed the first 10 days post-injury. The first day post-injury was studied in particular. Results: Arterial oxygen levels were higher and with greater variability on the first day post-injury, whereas it was more stable the following 9 days. Normal-to-high mean pO2 was significantly associated with better pressure autoregulation/lower pressure reactivity index ( P = .02) and lower cerebral MD-lactate ( P = .04) on day 1. Patients with limited cerebral energy metabolic substrate supply (MD-pyruvate below 120 µM) and metabolic disturbances with MD-lactate-/pyruvate ratio (LPR) above 25 had significantly lower arterial oxygen levels than those with limited MD-pyruvate supply and normal MD-LPR ( P = .001) this day. Arterial oxygenation was not associated with clinical outcome. Conclusions: Maintaining a pO2 above 12 kPa and higher may improve oxidative cerebral energy metabolism and pressure autoregulation, particularly in cases of limited energy substrate supply in the early phase of TBI. Evaluating the cerebral energy metabolic profile could yield a better patient selection for hyperoxic treatment in future trials.