van Santbrink H, Schouten J W, Steyerberg E W, Avezaat C J J, Maas A I R
Department of Neurosurgery, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
Acta Neurochir (Wien). 2002 Nov;144(11):1141-9. doi: 10.1007/s00701-002-1012-8.
Cerebral ischemia is considered a key factor in the development of secondary damage after Traumatic Brain Injury (TBI). Studies on Cerebral Blood Flow (CBF) have documented decreased flow in over 50% of patients with TBI, studied in the acute phase. Transcranial Doppler (TCD) sonography is a non-invasive technique, permitting frequent or continuous measurements of blood flow velocity in the basal cerebral arteries.
To investigate the potential of TCD to detect decreased blood flow velocity in the early phase after TBI;To investigate whether flow velocity differs between hemispheres in patients with focal lesions versus those with more diffuse injuries;To investigate if decreased blood flow velocity is indicative of cerebral ischemia, as evidenced by measurements of brain tissue pO(2).
TCD examinations were performed in 57 patients with severe TBI (GCS<or=8) daily over a period of 10 days, with particular attention focused on the first 72 hours, during which period examinations were performed more frequently. A low flow velocity state (LFVS) was defined as a flow velocity<or=35 cm/sec in one or both MCA's within 72 hours after trauma. PbrO(2) was measured in 33 patients with an intraparenchymal Clark type electrode (Licox).Patients were differentiated into those with primarily unilateral pathology on the admission CT scan versus those with primarily more diffuse or bilateral pathology. Outcome was evaluated at six months after injury, according to the Glasgow Outcome Scale (GOS).
A low flow velocity state was observed in 63% of patients studied. Decreased flow was most pronounced during the first eight hours after injury and was accompanied by high pulsatility indices, especially at the side of the lesion. Flow velocity increased significantly after this time period. Initial Vmca values had a strong correlation with ipsilateral measured PbrO(2) values (R=0.73). The occurrence of a LFVS was associated with poorer outcome (odds ratio 3.9).
TCD studies show reduction of cerebral blood flow velocity in the acute phase after traumatic brain injury. Decreased flow velocity is most pronounced ipsilateral to focal pathology. A low flow velocity state is probably due to high peripheral resistance, and is indicative of ischemia, as demonstrated by the association with decreased PbrO(2). A low flow velocity state is of prognostic value and identifies patients at increased risk for ischemia. Early TCD studies are recommended in TBI.
脑缺血被认为是创伤性脑损伤（TBI）后继发性损伤发展的关键因素。关于脑血流量（CBF）的研究表明，在急性期对超过50%的TBI患者进行研究时发现血流量降低。经颅多普勒（TCD）超声检查是一种非侵入性技术，可对大脑基底动脉的血流速度进行频繁或连续测量。
研究TCD检测TBI后早期血流速度降低的潜力；研究局灶性病变患者与弥漫性损伤患者半球间的血流速度是否存在差异；通过测量脑组织pO₂来研究血流速度降低是否表明存在脑缺血。
对57例重度TBI（格拉斯哥昏迷评分≤8分）患者在10天内每天进行TCD检查，特别关注前72小时，在此期间检查更为频繁。低血流速度状态（LFVS）定义为创伤后72小时内一侧或双侧大脑中动脉（MCA）的血流速度≤35 cm/秒。对33例患者使用实质内Clark型电极（Licox）测量脑组织氧分压（PbrO₂）。根据入院时CT扫描结果，将患者分为主要为单侧病变和主要为弥漫性或双侧病变两组。根据格拉斯哥预后量表（GOS）在伤后6个月评估预后。
在63%的研究患者中观察到低血流速度状态。伤后最初8小时内血流减少最为明显，并伴有高搏动指数，尤其是在病变侧。在此时间段后血流速度显著增加。初始大脑中动脉平均血流速度（Vmca）值与同侧测量的PbrO₂值密切相关（R = 0.73）。LFVS的出现与较差的预后相关（优势比为3.9）。
TCD研究表明创伤性脑损伤后急性期脑血流速度降低。血流速度降低在局灶性病变同侧最为明显。低血流速度状态可能是由于外周阻力高所致，并且如与PbrO₂降低相关所表明的那样，提示存在缺血。低血流速度状态具有预后价值，并可识别缺血风险增加的患者。建议对TBI患者尽早进行TCD研究。
