ИСТИНА

Objective: to evaluate the association between brain injury localization and type of sympathetic system reaction at acute phase of severe TBI. Background: A number of scientific studies points at sympathetic nervous system dysregulation after severe traumatic brain injury (TBI). The acute period of brain trauma is often characterized by hyperactivation of this system. It is well known that sympathetic nervous system has two chains: central (norepinephrinergic sympathetic fibers) and epinephrinergic fibers of adrenal medulla. This is the study of “norepinephrine / epinephrine” (NE/EN) and “norepinephrine / dopamine” (NE/DA) ratios in in acute period of severe TBI and their correlations with the localization of damaged regulative brain structures: brainstem, subcortical structures, frontal lobes. Design/Methods: 34 patients (9 women and 25 men; 31,8±13,8 y.o.) with severe TBI (GCS<8) were enrolled in this study. All patients underwent brain MRI scan (T1, T2, FLAIR, SWAN). Plasma levels of catecholamines were measured in acute period of TBI (1-3 days) by HPLC method. Sympathetic nervous system activation type was evaluated by NE/EN ratio: NE/EN ratio >5 pointed to central hyperactivation type, NE/EN ratio <2 witnessed to peripheral hyperactivation one. Results: Intact brainstem after TBI, as opposed to injured one, was associated with hyperactivity of central (norepinephrine) part of the sympathetic system in acute period. Damage of two main central regulatory structures of the sympathetic nervous system (frontal lobes and brainstem) lead to peripheral type of sympathetic nervous system activation with increased levels of epinephrine and decreased NE/EN ratio. Conclusions: brainstem damage can influence the response of SNS to traumatic brain injury and can modify the stress reaction process, which may have a crucial role for autoregulation, hemodynamics and neuroendocrine status of TBI patients.