Preliminary results in cochlear implant surgery without antromastoidectomy and with atraumatic electrode insertion: the endomeatal approach.

A surgical approach using the external auditory canal and the round window as a natural access pathway for cochlear implant positioning, the endomeatal approach, is described. This approach avoids performing an antromastoidectomy, the subsequent posterior tympanotomy and the promontorial cochleostomy. The endomeatal approach also allows an optimal insertion plane for electrode array atraumatic insertion through the round window.The technique was developed and practiced in 35 fresh temporal bones and then it was applied in ten patients. This surgery has an endomeatal first stage, which begins with a stapedectomy-like tympanomeatal flap. This flap allows an easy access to scala tympani via round window niche. The internal part of a groove is drilled on the posterior wall of the EAC. The groove is parallel to the EAC axis and starts in its inner border. Once the endomeatal stage is completed, a standard retroauricular approach is performed, in order to make the receptor-stimulator well and to complete the groove externally, until it connects the middle ear with the external mastoid surface. A flat second well is drilled in front of the first one to lodge the remaining electrode lead. In small children this well is deepened. The electrode array is introduced in the scala tympani through the RW and located into the groove. The electrode is covered and fixed inside the groove with bone paté. The extra length of the electrode lead is located in the second well and the receptor-stimulator is fixed in its well. The ground electrode is placed under the periosteum, the retroauricular incision is sutured, the tympanomeatal flap is restored and a dressing is placed into the EAC. Surgical time was significantly shorter than in standard approach. There were neither surgical nor healing complications. Electrode insertion was easy and complete and functional results were adequate. The goal of this approach is to avoid antromastoidectomy and posterior tympanotomy, which are replaced by the EAC groove. It is faster and safer, eliminating the risk of facial nerve injury. It also allows a better access to the round window, with a less traumatic electrode insertion, suitable for "soft surgery" performing. It may advantageously replace the classical transmastoideal approach.