Radiology Quiz Case 3

A 15-YEAR-OLD GIRL PRESENTED WITH A 2-week history of progressive facial palsy on the right side. No other otologic symptoms were identified. Physical examination revealed only a facial palsy, which was classified as House-Brackmann scale grade V. There were no signs of involvement of other cranial nerves. The findings of otoscopy and palpation of the parotid gland were normal. Audiometry showed a normal hearing threshold and an absent stapedial reflex in the right ear. The patient was treated with oral dexamethasone acetate and acyclovir, with no clinical improvement. A reformatted coronal computed tomogram (Figure 1), axial (Figure 2) and coronal (Figure 3) enhanced T1-weighted magnetic resonance images (MRIs), and a coronal T2-weighted MRI (Figure4) were obtained. What is your diagnosis?