Epineurial Pseudocyst of the Intratemporal Facial Nerve: A Case Series Study.

The goal of this case series was to describe the clinical and radiological characteristics of epineurial pseudocysts of the intratemporal facial nerve (EPIFs) and to discuss the relevance in clinical practice. A retrospective case series of 10 consecutive patients with EPIFs identified through computed tomography (CT), between 2009 and 2018. Morphological characteristics, coexisting pathology, facial nerve function, and evolution over time were analyzed. A unilateral EPIF was found in 5 patients (50%) and a bilateral EPIF was found in the other 5 (50%). The largest dimensions were observed in the coronal plane, with an average craniocaudal length of 6.0 mm (range, 3-9 mm). None of the patients presented with facial nerve dysfunction. Growth could not be observed in any of the patients. In 5 cases (33.3%), CT imaging showed a reduced transmastoid access to the facial recess caused by the EPIF. All EPIFs in this study were incidental findings. Facial nerve function was normal in all patients. Knowledge of EPIFs is important to perform safe cholesteatoma and cochlear implant surgery and to prevent unnecessary follow-up imaging.