Imaging findings in patients with X-linked nonsyndromic deafness and a POU3f4 mutation

Gong Wuxian; Gong Ruozhen; Zhao Bin

Abstract：Objective The aim of this study was to analyze HRCT and MRI findings in patients with X-linked nonsyndromic deafness and a POU3f4 mutation. Methods HRCT and MRI data of four patients (males, 2~19 years old) with a POU3f4 mu-tation were collected and a retrospective review was performed. Cochlea, internal auditory canal ( IAC) , vestibule, semicircular canals, vestibular aqueduct, nerve canals in the IAC fundus, stapes and cochlear nerve were evaluated on 2D images (multi-plan-ner reformation, MPR) and cochlear foramen on 3D images (CT virtual endoscopy, CTVE). Ten cases with normal hearing sub-jected to CT and MR exams were served as controls. Results Inner ear malformations were bilateral and symmetrical. Cochlear malformation was shown to consist of as a relatively normal outer coat shape, absence of a cochlear modilous, and a direct inter-communication between the IAC and cochlear inner cavity. The lateral portion of the IAC was dilated. A spiral cochlear inner cav-ity was observed with CTVE images versus a helical cochlear nerve foramen as seen in controls. The labyrinthine facial nerve canal and superior vestibular nerve canal were enlarged. The Bill' s bar was hypertrophic and partially pneumatized. A thickened stapes footplate was present and a fissura ante fenestram was absent in seven ears examined. A column shaped stapes was observed in one ear. Conclusion The absence of acochlear modilous with a dilatedlateral IAC and thickened stapes footplate were the remarka-ble features observed with imaging these in X-linkednon-syndromicdeafness patients with a POU3F4 mutation. Preoperative recog-nition of the image features in these patients is important because it precludes stapedectomy and indicates the risks in the surgery of cochlear implantation including CSF gusher and electrode insertion into IAC.