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The lion's mane sign: surgical results using the bilateral fronto-orbito-nasal approach in large and giant anterior skull base meningiomas.

OBJECT
Concerns about extreme peritumoral edema and its ensuing surgical and perioperative complications led the authors to use the bilateral fronto-orbito-nasal approach to remove midline anterior skull base meningiomas that were larger than 4 cm. The authors hypothesize that extreme vasogenic edema exemplified by finger-like hyperintensities extending into the bifrontal white matter and external capsule and/or the extreme capsule, coined the lion's mane sign (LMS), would help identify patients with a challenging postoperative course. They hypothesize that the LMS would better predict symptomatic postoperative cerebral edema than the edema index (EI).


METHODS
This is an observational case series of 9 patients. The authors noted the grade, pathology, tumor volume, EI, and the presence or absence of the LMS in all tumors. They used the intensive unit care (ICU) length of stay as a nonspecific measure reflecting postoperative symptomatic cerebral edema. Comparisons of edema-related postoperative complications and the EI were made between patients with and without an LMS.


RESULTS
Bifrontal hyperintensities, extending into at least three-eighths of the length of the external capsules on T2-weighted MRI, seen in 4 of 9 patients, portended a longer postoperative ICU stay. The presence of an LMS better predicted postoperative complications related to cerebral edema than tumor grade, pathology, volume, or EI.


CONCLUSIONS
The LMS predicts an increased duration of stay in the ICU after a bilateral fronto-orbito-nasal approach for resection of large and giant anterior skull base meningiomas. Furthermore, the LMS better predicted increased length of stay in the ICU than did the EI.