Background

There are no reported cases of negative CT head in the first six hours after a thunderclap headache in a patient found to have an aneurysmal subarachnoid hemorrhage (SAH).

Methods

We present a case of an anemic patient who experienced aneurysmal SAH with a negative head CT within the first 6 h following thunderclap headache.

Results

A 47-year-old woman presented with a thunderclap headache and examination showed somnolence and marked meningismus. After a negative CT head was obtained within the first 6 hours of symptom onset, a non-traumatic lumbar puncture (LP) showed consistently bloody collection tubes, prompting repeat imaging that demonstrated a tiny amount of intraventricular hemorrhage. CT angiography revealed an intradural carotid artery aneurysm, and pipeline embolization was successfully performed.

Conclusion

Non-contrast head CT may be falsely negative within the first 6 hours of aneurysmal SAH in the setting of anemia. In our case, the cause may not have been determined if an LP had not been performed. LP still has a role in diagnosing SAH, particularly in the setting of significant anemia, despite the high sensitivity of non-contrast head CT.

中文翻译：

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前六个小时CT阴性蛛网膜下腔出血

背景

未发现有动脉瘤性蛛网膜下腔出血（SAH）的患者发生雷击性头痛后的头六个小时内，CT头阴性的病例。

方法

我们介绍了一例贫血患者，该患者在发生雷声击伤后的头6 h内出现动脉瘤SAH，头部CT阴性。

结果

一名47岁的妇女出现了雷声般的头痛，经检查显示有嗜睡和明显的脑膜炎。在症状发作的前6个小时内获得的CT头阴性后，非创伤性腰穿（LP）始终显示采集管充满血迹，从而促使重复成像显示少量脑室内出血。CT血管造影显示硬膜内颈动脉瘤，并成功进行了管道栓塞术。

结论

在贫血的情况下，在动脉瘤性SAH的前6个小时内，非对比头CT可能会假阴性。在我们的情况下，如果未执行LP，则可能无法确定原因。尽管无对比头颅CT的敏感性很高，但是LP在SAH的诊断中仍具有重要作用，特别是在严重贫血的情况下。