Sympathetic control of cutaneous blood flow and blood pressure in human spinal cord injury

虽然脊髓损伤会导致神经系统的破坏性变化，瘫痪和感觉丧失，但对交感神经系统的变化知之甚少。交感神经系统密切参与血压、血流和体温的持续控制。交感神经控制的丧失可能发生在脊髓损伤之后。下行通路的中断可导致胸腰段交感神经流出部分或完全丧失。完全去中心化可导致自主神经反射异常（自主神经反射亢进），其中源自病变下方的感觉刺激引起对血管的交感神经驱动的反射增加，导致血管收缩。正因为如此，血压可能会突然升高，并保持在如此高的水平，中风和（偶尔）心脏骤停可能会发生。这种现象，自主神经反射障碍，被认为是一种医疗紧急情况。自主神经反射异常的典型主观症状包括搏动性头痛、头部刺痛或鼻塞;病变部位上方的出汗和潮红是促使医务人员测量血压和定位感觉刺激源（通常是膀胱膨胀或结肠嵌塞，有时是压疮或嵌甲）的临床症状。然而，通常亚临床发作未被发现，这种无声反射障碍现象越来越受到关注。该项目将开发评估脊髓损伤患者病变下方交感神经系统的完整性和状态的方法，并表征反射激活交感神经元的放电特性。

While spinal cord injury can cause devastating changes in the nervous system paralysis and loss of sensation relatively little is known about changes to the sympathetic nervous system. The sympathetic nervous system is intimately involved in the ongoing control of blood pressure, blood flow and temperature control. Loss of sympathetic control can occur following spinal cord injury. Interruption of descending pathways can result in partial or complete loss of sympathetic outflow from the thoracolumbar segments. Complete decentralization can result in autonomic dysreflexia (autonomic hyperreflexia), in which sensory stimuli originating below the lesion evoke a reflex increase in sympathetic drive to the blood vessels, causing them to constrict. Because of this, blood pressure may rise suddenly and remain at such high levels that stroke and (occassionally) cardiac arrest may occur. This phenomenon, autonomic dysreflexia, is considered a medical emergency. The typical subjective signs of autonomic dysreflexia include a throbbing headache, tingling in the head or nasal congestion; sweating and flushing above the lesion are clinical signs that prompt medical staff to measure blood pressure and to locate the source of sensory irritation (usually a distended bladder or impacted colon, sometimes a pressure sore or ingrown toenail). Commonly, however, subclinical episodes go undetected, and this phenomenon of silent dysreflexia is of increasing concern. This project will develop means of assessing the integrity and state of the sympathetic nervous system below a lesion in patients with spinal cord injury and characterize the firing properties of reflexly activated sympathetic neurones.