Intracranial mass lesions can lead to transtentorial uncal herniation, and pupillary asymmetry is a well-recognized sign of impending cerebral herniation. Impending uncal herniation can lead to ipsilateral, bilateral, or uncommonly the contralateral pupillary dilatation. We report a case of a 22-year old, who had contralateral pupillary dilatation due to expanding intracranial mass lesion and recovered well after neurosurgical intervention. This case illustrates contralateral pupillary dilatation (“false-localizing” sign) in a sub-group of patients, and if untreated and ICP continues to rise, this is followed by ipsilateral pupil dilatation.

中文翻译：

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对侧瞳孔扩张和偏瘫：重新审视Kernohan的切口

颅内块状病变可导致跨膜不全疝，瞳孔不对称是即将发生脑疝的公认标志。即将发生的非标定性疝会导致同侧，双侧或不常见的对侧瞳孔扩张。我们报告了一例22岁，由于扩大颅内肿块病变而对侧瞳孔扩张，并在神经外科手术后恢复良好。该病例说明了亚组患者的对侧瞳孔扩张（“假定位”征象），如果未经治疗且ICP继续升高，则继之以同侧瞳孔扩张。