Case of the Month – July 2016 Cystic mass in posterior cranial fossa presenting with sudden onset of trigeminal neuralgia by Luciano Mastronardi, MD, PhD, Ettore Carpineta, MD, Raffaelino Roperto, MD, San Filippo Neri Hospital, Rome, Italy Case Presentation A 62 years old female, with a sudden onset of left trigeminal neuralgia (mainly 1st and 2nd branches) caused by a large cystic lesion of the left posterior cranial fossa, at the level of the root entry zone (REZ) of the 5th nerve. On neurological examination she showed a slight gait ataxia and diminished sensation on the left hemiface (except for the third trigeminal branch). Other cranial nerves were in order. Question Title * 1. What are the possible lesional locations? Right basal ganglia Gasserian ganglion Cerebellar hemisphere Cerebellopontine angle Next