1 Department of Electrical & Computer Engineering, COMSATS University Islamabad, Sahiwal, Pakistan.
2 International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
J Neurotrauma. 2019 May 1;36(9):1487-1490. doi: 10.1089/neu.2018.5931. Epub 2019 Jan 8.
The capacity of the cerebrovasculature to buffer changes in blood pressure (BP) likely plays an important role in the prevention of stroke, which is three- to fourfold more common after spinal cord injury (SCI). Although the directional relationship between BP and cerebral blood flow (CBF) has traditionally been thought to travel solely from BP to CBF, a Cushing-like mechanism functioning in the inverse direction, in which changes in CBF influence BP, has recently been revealed using Granger causality analysis. Although both CBF buffering of BP and the Cushing-like mechanism are influenced by the sympathetic nervous system, we do not understand the impact of disruption of descending sympathetic pathways within the spinal cord, caused by cervical SCI on these regulatory systems. We hypothesized that people with cervical SCI would have greater BP to CBF transmission, as well as a reduced Cushing-like mechanism. The directional relationships between mean arterial BP (MAP; Finometer PRO) and middle cerebral artery blood velocity (MCAv; transcranial Doppler) were assessed at rest in 14 cervical SCI subjects and 16 uninjured individuals using Granger causality analysis, while also accounting for end-tidal CO tension. Those with SCI exhibited 66% increased forward MAP→MCAv information transmission as compared with the uninjured group ( 0.0003), indicating reduced cerebrovascular buffering of BP, and did not have a predominant backward Cushing-like MCAv→MAP phenotype. These results indicate that both forward and backward communication between BP and CBF are influenced by SCI, which may be associated with impaired cerebrovascular BP buffering after SCI as well as widespread BP instability.
脑血管对血压（BP）变化的缓冲能力可能在预防中风方面发挥着重要作用，而中风在脊髓损伤（SCI）后发生的概率要高出三到四倍。尽管传统上认为 BP 和脑血流（CBF）之间的方向关系仅从 BP 到 CBF 传递，但最近使用格兰杰因果分析揭示了一种相反方向的库欣样机制，其中 CBF 的变化会影响 BP。尽管 CBF 对 BP 的缓冲作用和库欣样机制都受到交感神经系统的影响，但我们并不了解颈 SCI 导致脊髓内下行交感神经通路中断对这些调节系统的影响。我们假设颈 SCI 患者的 BP 到 CBF 传递会增加，而库欣样机制则会减弱。使用格兰杰因果分析评估了 14 名颈 SCI 患者和 16 名未受伤个体在静息状态下平均动脉压（MAP；Finometer PRO）和大脑中动脉血流速度（MCAv；经颅多普勒）之间的方向关系，同时还考虑了呼气末 CO 张力。与未受伤组相比，SCI 组的正向 MAP→MCAv 信息传递增加了 66%（0.0003），表明 BP 的脑血管缓冲能力降低，并且没有明显的反向库欣样 MCAv→MAP 表型。这些结果表明，BP 和 CBF 之间的前向和后向通讯都受到 SCI 的影响，这可能与 SCI 后脑血管 BP 缓冲受损以及广泛的 BP 不稳定有关。
