BACKGROUND Neurogenic orthostatic hypotension (nOH) causes pathological falls in standing blood pressure that may or may not be symptomatic. nOH also raises the risk of poor neurological outcomes irrespective of symptom presence, possibly reflecting subclinical cerebral hypoperfusion. Dynamic changes in cerebral blood flow velocity (CBFv) help infer how blood pressure fluctuations influence CBFv and cerebral autoregulation. Whether CBFv is impacted in nOH relative to related conditions without nOH and healthy controls (HC) remains unresolved. Whether nOH symptoms reflect greater CBFv falls is also unclear. This review aimed to compare CBFv between nOH and HC, nOH and disease-matched controls (eg, Parkinson disease±nOH), and between symptomatic and asymptomatic nOH. METHODS Embase and MEDLINE were searched up to April 2024. Means, SDs, and sample sizes for supine and upright CBFv were extracted to generate standardized effect sizes (Hedge g). Random-effects modeling compared postintervention between-group effect sizes. RESULTS Seventeen studies were included for review. Thirteen studies were suitable for meta-analysis comparing nOH to HC, 2 comparing disease-matched controls to nOH and to HC, and 3 for symptomatic comparisons. Compared with HC, nOH had larger drops in CBFv (Hedge g, -0.64 [95% CI, -0.85 to -0.44]; P<0.001). CBFv falls between nOH and disease-matched controls were similar (P=0.17). Symptomatic nOH had larger CBFv drops (Hedge g, 0.84 [95% CI, 0.212-1.461]; P=0.009) than asymptomatic nOH. CONCLUSIONS nOH causes significant orthostatic reductions in CBFv compared with HC, and symptomatic patients experience greater falls in CBFv than asymptomatic patients. Recognizing the clinical implications of CBFv in nOH is crucial for mitigating adverse outcomes.

中文翻译：

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神经源性直立性低血压的脑血流动力学：系统评价和荟萃分析。


背景 神经源性直立性低血压 （nOH） 会导致站立血压的病理性下降，这可能是也可能不是症状。无论症状是否存在，nOH 都会增加神经系统结局不良的风险，这可能反映了亚临床脑灌注不足。脑血流速度 （CBFv） 的动态变化有助于推断血压波动如何影响 CBFv 和脑自动调节。相对于没有 nOH 和健康对照 （HC） 的相关疾病，CBFv 是否在 nOH 中受到影响仍未解决。nOH 症状是否反映 CBFv 下降幅度更大也尚不清楚。本综述旨在比较 nOH 和 HC、nOH 和疾病匹配对照 （例如，帕金森病±nOH） 以及有症状和无症状 nOH 之间的 CBFv。方法 检索 Embase 和 MEDLINE 截至 2024 年 4 月。提取仰卧位和直立位 CBFv 的均值、SD 和样本量以生成标准化效应量 （Hedge g）。随机效应模型比较了干预后组间效应大小。结果 纳入 17 项研究以供综述。13 项研究适合将 nOH 与 HC 进行比较的荟萃分析，2 项研究将疾病匹配的对照与 nOH 和 HC 进行比较，3 项研究用于症状比较。与 HC 相比，nOH 的 CBFv 下降幅度更大（对冲 g，-0.64 [95% CI，-0.85 至 -0.44];P<0.001）。CBFv 在 nOH 和疾病匹配的对照之间下降相似 （P=0.17）。有症状的 nOH 的 CBFv 下降幅度较大 （Hedge g，0.84 [95% CI，0.212-1.461];P=0.009）比无症状的 nOH 多。结论与 HC 相比，nOH 导致 CBFv 的直立性显着降低，有症状患者的 CBFv 下降幅度大于无症状患者。认识到 CBFv 在 nOH 中的临床意义对于减轻不良结局至关重要。