Imaging Analysis In X-linked Non-syndromic Deafness Patients With A POU3F4Mutation

Imaging analysis of in X-linked non-syndromic deafness patients with a POU3F4mutationPart1. Imaging analysis of inner ear malformations in X-linked non-syndromic deafness patients with a POU3F4mutationObjective:The aim of this study was to analyze HRCT and MRI findings of inner ear in patients with X-linked non-syndromic deafness and a POU3f4mutation.Methods:HRCT and MRI data of6patients (males,2-19years old) with a POU3f4mutation were collected and a retrospective review was performed.2cases were from the same family and other cases from different families. Images data of3causative gene carriers from different families were also evaluated. Cochlea, IAC, vestibule, semicircular canals, vestibular aqueduct, nerve canals in the IAC fundus, stapes and cochlear nerve were evaluated on2D images (MPR), cochlear foramen on CTVE images, shape of inner ear on VRT images.30cases with normal hearing subjected to CT and MR exams served as controls.Results:1. Patients group:inner ear malformations were bilateral and symmetrical in every patient.(1) Cochlear malformation in6patients (12ears) was shown to consist of as a relatively normal outer coat shape, absence of a cochlear modilous, and a direct intercommunication between the IAC and cochlear inner cavity. Both interscalar septa between the basal/middle turn and middle/apical turn were present. Cochlear modiolus and bony spiral lamina were absent, which resulted in a cochlear spiral canal opening MR images revealed that a fluid rilled cavity replaced the cochlear modiolus and spiral lamina. No bony or soft septum were present between the cochlear inner cavity and IAC. Cochlear nerve canal was enlarged.(2)The lateral portion of the IAC was dilated in6patients (12ears).(3) The labyrinthine facial nerve canal and superior vestibular nerve canal were enlarged in6patients (12ears). The Bill’s bar between the facial nerve canal and superior vestibular nerve canal was hypertrophic and partially pneumatized. The singular canal was opened in medial portion of IAC. In one case (2ears), the singular canal was enlarged. The other canals in IAC fundus had normal shapes.(4) The semicircular canals shapes were normal in all patients. In3cases (6ears), the lateral and posterior semicircular canals were enlarged, the bony island in lateral semicircular canal was smaller. Bony wall of posterior semicircular was partially absent in one case (2ears).(5) The first part of vestibular aqueduct was enlarged in2cases (4ears). In other cases, the shape of vestibular aqueduct was normal. The endolymphatic sac was normal in all cases.(6) The vestibule of two patients (4ears) contained a cystic bulge located in the superior margin as observed with both coronal CT and MR. The small sac protruding upward, located between the superior semicircular canal feet.(7) A helix-like shape was present in the6patients on CTVE image, but differed significantly from the control group. Due to the absence of the cochlear modiolus and spiral lamina, the helix in these patients was formed by the opening of the cochlear spiral canal. The distance between the facial nerve foramen and superior vestibular nerve foramen in the IAC fundus was enlarged.(8) As determined by MR, the cochlear nerve entered the inner cochlear cavity directly from the IAC in all patients(12ears).2. Causative gene carriers group:Dilated lateral portion of IAC was found in3causative gene carriers (9ears). In one of them (2ears), the labyrinthine facial nerve canal and superior vestibular nerve canal were enlarged. The other inner ear structures were normal in3causative gene carriers.Conclusions:1. There are similar image findings in6patients with different loci of POU3F4mutations. The cochlear malformation (a relative normal shape of outer coat, absence of a cochlear modilous and a direct intercommunication between the IAC and cochlear inner cavity), a dilated lateral IAC,enlarged labyrinthine facial nerve canal and superior vestibular nerve canal were the remarkable features observed with imaging these in X-linked non-syndromic deafness patients with a POU3F4mutation.2. Accompanied malformations including malformed vestibule, dilated first part on vestibular aqueduct, enlarged singular canal, enlarged lateral and posterior semicircular canals were found in some patiens.3. Dilated lateral portion of IAC was found in causative gene carriers. In some carriers, the labyrinthine facial nerve canal and superior vestibular nerve canal were enlarged. Part2. HRCT evaluation of stapes using MPR technique in X-linked non-syndromic deafness patients with a POU3F4mutationObjective:The aim of this study was to analyze the stapes conditions in patients with X-linked non-syndromic deafness and a POU3f4mutation on HRCT images.Methods:HRCT data of6patients (males,2-19years old) with a POU3f4mutation were collected and a retrospective review was performed.2cases were from the same family and other cases from different families. Images data of3causative gene carriers from different families were also evaluated.30cases with normal hearing subjected to CT exams served as controls. An oblique image to show all the structures of stapes was reconstructed using MPR technique. The morphological changes of stapes, thickness of stapes footplate and the display rate of fissura ante fenestram on the MPR image in three groups were evaluated and compared. The statistical analysis was performed in SPSS17.0program.Results:(1) There is significant difference in footplate thickness and the display rate of fissura ante fenestram between patient and control groups.(2) There is on significant difference in footplate thickness and the display rate of fissura ante fenestram between causative gene carriers and control groups.(3) Stapes malformations were found in6paitents (11ear), but it may be unsymmetrical in the same patient. Only a normal stapes was shown in one patient. The stapes footplate in the patients was more thickened and the display rate of fissura ante fenestram in patients was lower than control group. A column shaped stapes was observed in2ears. Hypoplastic anterior crus of stapes was found in1ear of one patients. Hypoplastic posterior crus of stapes was aslo found in1ear of another patient. Dysplastic anterior crus of stapes was found in1ear. Bilateral fistula of stapes footplate was found in one patient.Conclusions:(1) The stapes footplate in the patients with a mutation of POU3F4is more thickened than normal people.(2) The display rate of fissura ante fenestram n the patients with a mutation of POU3F4is more lower than normal people.(3) The absence of fissura ante fenestram and thickened stapes footplate were the remarkable features of congenital fixed stapes observed with imaging these in X-linked non-syndromic deafness patients with a POU3F4mutation. Perforation of stapes footplate and perilymph fistula was observed in2ears of one patient. Abnormalities of stapes structures above the footplate were also shown in the patients with a mutuation of POU3F4including column shaped stapes, dysplastic anterior or posterior crus of stapes.