弥漫性轴突损伤早期超微结构改变

目的通过观察弥漫性轴突损伤(DAI)患者伤后早期轴突的超微结构变化以探索DAI的发生机理.方法对12例DAI患者的14份活体脑组织标本进行透射电镜检查.结果 DAI患者在伤后早期可发生多方面的轴突改变,包括(1)轴突的细胞骨架破坏;(2)轴膜改变;(3)膜性细胞器的变化;(4)髓鞘的改变;(5)轴突出现肿胀和离断,轴突近侧断端呈现球状.结论在DAI的发生中,可能有多种机理参与.推测,在受到足够强的外力作用时,一些管径较细的轴突可能会立即断裂;其它受损轴突则会出现进行性的延迟性轴突断裂.在此演化过程中,细胞骨架破坏和轴膜受损继而通透性改变可能是造成轴突局灶性轴浆转运障碍最终离断的最重要的因素.

Early ultrastructural changes of diffuse axonal injury in patients with severe head injury

Objective To obtain more knowlege about the pathogenesis of diffuse axonal injury(DAI) via observing the ultrastructural axonal changes in the patients with DAI after traumatic brain injury. Methods 14 bioptic samples of the cerebral white matter in 12 patients with DAI were examined with transmission electratic microscope. Results We found that traumatically induced axonal pathological changes in humans may be summarized as follows: (1) cytoskeletal abnormalities; (2) disruption and infolding of the axolemma; (3) swelling and focal accumulation of mitochondria and endoplasmic reticula; (4) infolding and blebbing of myelin sheath and separation of myelin lamellae; (5) axonal swellings and disconnection giving rise to proximal axonal bulbs. Conclusion Possibly, there are differing patterns of mechanism involved in the pathogenesis of traumatically induced axonal injury. It is suggested that fragmentation of small calibre axons can occur immediately after the time of injury and then progressive axonal swelling and delayed axotomy takes place in the other injured axons, in which focal cytoskeletal perturbation and axolemmal disruption followed by permeabilization possibly are the most important factors resulting in impairment of axoplasmic transport and secondarily axonal disconnection.