[Role of modern imaging (tomodensitometry and MRI) in cochlear implantation in children]

Since 1989, 40 patients have received implants in the O.R.L. ward of the Hôpital d'Enfants Armand Trousseau (Paris). Over the past 2 years, 17 children have undergone radiological assessment combining M.R.I. anf high resolution C.T scanning. Imagery is not the essential stage, and is only used after assessment by a multidisciplinary team. However, the imagery results influence the choice of implant, and sometimes the side to be implanted. C.T is always the first stage as it detects congenital abnormalities, and, for children with a history of bacterial meningitis, it can detect signs of labyrinthine ossification which contraindicate cochlear implantation. These signs are not always visible using tomodensitometry, especially when fibrosis within the canal has not yet ossified. This examination also provides for post-operative confirmation of implant position in case of failure or complication. Over the past 3 years, Magnetic Resonance Imagery has been combined with tomodensitometry, especially with children having a past medical history of meningitis. This examination provides a basis for evaluating the liquid nature of the labyrinth. A G.E. Sygna 1.5 T was used by the authors, employing sequences of volumetric acquisition (S.S.F.P. with 1.5 mm image slices and an angle of 15 to 35 degrees). Hence, modern imagery plays an important role when the decision to implant has already been taken, particularly in the case of profoundly deaf children. M.R.I. is always used in combination with a scanner in cases involving children with a past medical history of meningitis.