Preoperative integrated imaging in paediatric cochlear implantation

Sensorineural hearing loss affects one to two children out of 1000 born apparently healthy and 9% approximately of those born with the risk of different pathologies. The origin of premature deafness is unknown in 25% of children whereas it is genetic in some cases. Prevention and early diagnosis, possibly within six to eight months, aim to avoid deafness becoming a cause of disability. The aim of the present study was to establish the optimal preoperative assessment with a diagnostic imaging protocol involving the integrated use of CT and MRI in the selection of the candidates for cochlear implantation. Twenty children were assessed, divided into three different groups: A) those who had CT only; B) those who had only MR; C) those who had both CT and MRI. The purpose was to estimate diagnostic accuracy in preoperative planning and the role of imaging in the diagnostic protocol for children's deafness. The petrous pyramid was studied with a CT Picker PQ 6000 system to high resolution in the axial and coronal planes, and with an MR Intera Philips 0.5 T device by means of acquisition of sequences B-TFE T2 3D and MIP reconstructions on radial coronal plans. This study was completed successfully for morphological brain MRI examination to complete the diagnosis. The following abnormalities were found in six patients (30%): one case of incomplete partition (Mondini malformation); two cases of vestibular aqueduct enlargement; two cases with anomalous jugular bulb positioning; one case with cochlear ossification. In the remaining 70%: eight patients had no anatomical anomalies; CT and MRI imaging were normal in six patients with minor abnormalities disclosed at surgery (one case of the stapedial artery emerging from the promontory); three anatomical variants of the round window, and two abnormal course of the facial nerve). We emphasize the importance of integrated CT and MRI imaging in the study of children with sensorineural hearing loss. The combination of CT and MRI has been shown to be superior to either modality used alone in view of "risk-free" cochear implantation. High resolution computed tomography and magnetic resonance images obtained by B-TFE T2-weighted 3D sequences help the surgeon in planning the operation and predict operative difficulty and potential complications in paediatric cochlear implant candidates.