Pediatric Cochlear implant soft failure.

PURPOSE

Hard cochlear implant failures are diagnosed by objective tests whereas soft failures are suspected on the basis of clinical signs and symptoms. This study reviews our experience with children in tertiary pediatric medical center who underwent revision cochlear implantation, with emphasis on soft failures.

MATERIALS AND METHODS

Children (age<18years) who underwent revision cochlear implantation from 2000 to 2012 were identified by database search. Pre- and post-explantation data were collected.

RESULTS

Twenty-six revision surgeries were performed, accounting for 7.4% of all cochlear implant surgeries at our center during the study period. The pre-explantation diagnosis was hard failure in 7 cases (27%), soft failure in 12 (46%), and medical failure in 7 (27%). On post-explantation analysis, 7/12 devices from the soft-failure group with a normal integrity test had abnormal findings, yielding a 63% false-negative rate (12/19) for the integrity test. All children regained their initial performance. Compared to hard failures, soft failures were associated with a shorter median time from first implantation to symptom onset (8 vs 25months) but a significantly longer time from symptom onset to revision surgery (17.5 vs 3months; P=0.004).

CONCLUSIONS

Soft cochlear implant failure in young patients poses a diagnostic challenge. A high index of suspicion is important because a delayed diagnosis may have severe consequences for language development. A normal integrity test does not unequivocally exclude device failure and is unrelated to functional outcome after revision surgery. Better education of parents and rehabilitation teams is needed in addition to more accurate diagnostic tests.