A widened subarachnoid space might be pathologic, potentially pathologic, or simply a normal developmental variant. However, the definition of a normal subarachnoid space width in infants remains unclear, especially on computed tomography (CT) images. To determine the physiological subarachnoid space width among infants aged 1-24 months, its upper limit, and changes with age, we measured the cerebrospinal fluid width on 538 CT images. Measurements were obtained at fixed planes and fixed positions to prevent variance and increase comparability between patients. We observed an asymmetry in the cerebrospinal fluid width of the temporal region. The width increased in all positions until 4-6 months of age, after which it began to decrease, reaching a relatively stable range in infants aged 13-24 months. We suggest considering the 95th percentile of the cerebrospinal fluid width as the upper limit. The correlation between age and the subarachnoid space width should be considered during clinical diagnosing.

扩大的蛛网膜下腔可能是病理性的、潜在的病理性或仅仅是正常的发育变异。然而，婴儿正常蛛网膜下腔宽度的定义仍不清楚，尤其是在计算机断层扫描 (CT) 图像上。为了确定 1-24 个月婴儿的生理蛛网膜下腔宽度、其上限和随年龄的变化，我们在 538 幅 CT 图像上测量了脑脊液宽度。在固定平面和固定位置获得测量值以防止差异并增加患者之间的可比性。我们观察到颞区脑脊液宽度不对称。所有体位的宽度都增加，直到4-6个月大，之后开始减少，在13-24个月大的婴儿中达到一个相对稳定的范围。我们建议将脑脊液宽度的第 95 个百分位作为上限。临床诊断时应考虑年龄与蛛网膜下腔宽度的相关性。