Perry Jeffrey J, Sivilotti Marco L A, Stiell Ian G, Wells George A, Raymond Jenny, Mortensen Melodie, Symington Cheryl
Department of Emergency Medicine, University of Ottawa, ON, Canada.
Stroke. 2006 Oct;37(10):2467-72. doi: 10.1161/01.STR.0000240689.15109.47. Epub 2006 Aug 31.
The absence of xanthochromia in the cerebrospinal fluid (CSF) is often used to exclude subarachnoid hemorrhage (SAH). Authorities advocate spectrophotometry to measure xanthochromia, but most North American hospitals use visual inspection. We studied the diagnostic accuracy of spectrophotometry for SAH, and its potential impact on current practice.
This was a prospective cohort study comparing the diagnostic accuracy of tests. The study was set in 3 university-affiliated tertiary care emergency departments. We enrolled consecutive neurologically intact adults with nontraumatic headache undergoing lumbar puncture (LP) to rule out SAH. CSF was centrifuged, frozen and analyzed later in batch. SAH was defined by (1) subarachnoid blood on CT, (2) >5x10(6) red blood cells/L in the final CSF tube and positive angiography, or (3) visible xanthochromia in CSF and positive angiography. All subjects lacking a normal CT and LP were telephoned at 30 days.
We enrolled 220 patients (mean age 42+/-16 years; CT rate 87.7%; angiography rate 5.9%). Two SAHs were identified: 1 with red blood cells without xanthochromia in the CSF and 1 with visibly xanthochromic CSF. The specificity of xanthochromia was 97% (95% CI: 92% to 99%) for visual inspection, but as low as 29% (95% CI: 23% to 35%) for 2 of the spectrophotometric definitions. Introducing spectrophotometry could lead to angiography in as many as 11% to 71% of patients undergoing LP.
Spectrophotometric definitions of xanthochromia have only moderate to low specificity for SAH. Using spectrophotometry could increase angiography rates, thereby identifying more incidental aneurysms, increasing patient anxiety and exposing patients to unnecessary surgical or investigational complications without benefit.
脑脊液（CSF）中无黄变常被用于排除蛛网膜下腔出血（SAH）。权威机构提倡采用分光光度法测定黄变，但北美大多数医院仍采用目视检查。我们研究了分光光度法对SAH的诊断准确性及其对当前实践的潜在影响。
这是一项比较检测诊断准确性的前瞻性队列研究。该研究在3家大学附属三级护理急诊科进行。我们纳入了连续的无创伤性头痛且神经系统完好的成年人，他们接受腰椎穿刺（LP）以排除SAH。脑脊液经离心、冷冻后分批进行分析。SAH的定义为：（1）CT显示蛛网膜下腔出血；（2）最后一管脑脊液中红细胞计数>5×10⁶/L且血管造影阳性；或（3）脑脊液中可见黄变且血管造影阳性。所有CT和LP结果异常的受试者在30天时接受电话随访。
我们纳入了220例患者（平均年龄42±16岁；CT检查率87.7%；血管造影检查率5.9%）。确诊2例SAH：1例脑脊液中有红细胞但无黄变，1例脑脊液明显黄变。目视检查黄变的特异性为97%（95%CI：92%至99%），但分光光度法的2种定义的特异性低至29%（95%CI：23%至35%）。采用分光光度法可能导致多达11%至71%接受LP的患者接受血管造影检查。
分光光度法对SAH的黄变定义特异性仅为中度至低度。采用分光光度法可能会提高血管造影检查率，从而发现更多偶然的动脉瘤，增加患者焦虑，并使患者遭受不必要的手术或检查并发症而无益处。
