Morphological correlates of hemodynamic changes in peripheral nerves after high-energy injury

Introduction. Given the high frequency of neurological complications after mine-blast injuries, the most common trauma in contemporary armed conflicts, we aimed to characterize the time-dependent morphological and functional changes in the blood vessels of the central segment of a peripheral nerve following traumatic limb amputation caused by mine-blast injury. Materials and methods. We examined 50 segments of tibial nerves obtained on days 1–30 after mine-blast injury using histology, histochemistry (orcein), and immunohistochemistry (antibodies to CD31, α-SMA, and Ki-67). Morphometry was performed in three zones of the central nerve fragment: A, 1–2 cm from the amputation level; B, 5–7 cm; and C, 8–30 cm (within the same segment). Wagenvoort and Kernohan perfusion indices were calculated. Statistical analysis employed the Kruskal–Wallis test and linear mixed-effects models. Results. On days 1–2, we observed hemorrhages, traumatic edema, multiple fibrinous and hyaline thrombi, air/fat/tissue emboli, and a patchy arteriolar spasm. A peak of vasodilation was detected on days 3–7: the mean arteriolar luminal diameter approximately doubled (p<0.001), while the Wagenvoort and Kernohan indices decreased by 25.9±4.3 and 1.46±0.31, respectively (p<0.001). Between days 8 and 30, numerous CD31+ thin-walled vessels of granulation tissue formed across all nerve compartments; by day 13, perfusion metrics increased despite persistent luminal dilatation; and by day 30, they approached baseline values against the background of tunica intima and tunica media thickening. Conclusion. Following mine-blast injury, a triphasic vascular response is mediated by both local and systemic factors: initial spasm of the vasa nervorum, subsequent vasodilation corresponding to the hypodynamic (torpid) phase of traumatic shock, and delayed perfusion decline accompanied by focal neoangiogenesis and reorganization of granulation tissue. Keywords: mine-blast injury, peripheral nerve, vasa nervorum, Wagenvoort index, Kernohan index