Prospective Long-term Auditory Results of Cochlear Implantation in Prelinguistically Deafened Children: The Importance of Early Implantation MANUEL MANRIQUE, FRANCISCO JAVIERCERVERA-PAZ, ALICIA HUARTE and MAITE MOLINA From the Department of Otorhinolaryngology, Head and Neck Surgery, University of Navarra Hospital and Medical School, Pamplona, Spain Manrique M, Cervera-Paz FJ, Huarte A, Molina M. Prospective long-term auditory results of cochlear implantation in prelinguistically deafened children: the importance of early implantation . Acta Otolaryngol 2004 Suppl 552: 55  /63. The objectives of this study were to report the long-term auditory results of prelinguistically deafened children with bilateral profound hearing impairment treated with a cochlear implant (CI); to analyze the role of auditory stimulation in the development of communicating abilities in early implanted children; and to define the limits of the auditory critical period. It was designed as a prospective cohort single-subject repeated-measures study of children with bilateral profound hearing impairment treated with a CI at a tertiary referral center with a pediatric CI program since 1991. A total of 182 children with bilateral prelinguistic hearing impairment of profound degree treated with a Nucleus CI were enrolled in the study. Eighty-six children received a Nucleus 22 CI and 74 received a Nucleus 24. For data analyses the children were categorized by ages: 0  /3 years of age (n /94); 4  /6 years (n /36); 7  /10 years (n /30); 11 /14 years (n /22). The children were evaluated with a protocol that included tests of audition and speech perception, with closed-set (Vowel Confusion test, Series of Daily Words) and open-set tests (e.g. bisyllables, CID Sentences, CID Sentences adapted for children). Pure-tone averages significantly improved for all children in all groups with the CI comparedwith preoperative values. Nevertheless, only children implanted before the age of 6 years developed a high ability for recognition of bisyllables and sentences in an open-set. Results show that the earlier the implantation is undertaken, the better the performance outcome. Children implanted outside of the auditory critical period demonstrated significantly poorer performance, suggesting the occurrence of irreversible changes in the central auditory system. In conclusion, eligible children should receive a CI as soon as bilateral profound hearing impairment is diagnosed. This usually permits them to achieve high-performance levels on speech and language measures and potentially integration into an oral communication environment. Key words: auditory critical period, hearing impairment, inner ear surgery , neural plasticity , treatment outcome . INTRODUCTION Clinical experiences, particularly in the last 10 years, have shown the importance of early implantation in order to take advantage of the higher degree of auditory plasticity in infancy. Cochlear implantation is currently one of the possible choices for the rehabilitation of profound sensorineural hearing im- pairment in children, regardless of a prelinguistic or postlinguistic onset (1  /6). It has also been shown that early implantation is technically possible without increasing the occurrence of complications (7  /12). In addition, technical advances such as neural response telemetry have greatly facilitated the program of speech processors for non-cooperative patients, especially in the case of children under the age of 2 years (13). These and other aspects will be addressed in this paper, following the experience in our cochlear implant program with more than 400 implantees since 1989, two-thirds of whom are pediatric patients. METHODOLOGY Patients A prospective study was undertaken in a consecutively implanted group of 182 congenitally or prelinguisti- cally deaf children. Prelinguistic hearing impairment is defined as that occurring before the age of 2 years. The children were grouped by age at implantation: group 1: 0  /3 years (n /94); group 2: 4  /6 years (n /36); group 3: 7  /10 years (n /30); and group 4: 11 /14 years (n /22). Demographic and relevant data for the groups are shown in Table I. In addition, as indicated in the results, subgroups of children from groups 1 and 2 will be studied further separately. Preoperativeevaluation All children were evaluated according to a preopera- tive protocol that consisted of the following. (i) History, physical and otorhinolaryngological ex- amination. (ii) Neuropediatric examination and family evaluation. Psychological assessment was completed to evaluate the children’s cognitive abilities, and to rule out patients with other neurological conditions that may compromise postoperative performance. (iii) Auditory evaluation and speech perception testing (see further). (iv) Auditory brainstem responses (ABRs): ABRs were recorded, at least twice, in all infants and children before surgery. To determine the auditory threshold, the wave V latency was evaluated at consecutive intensities of stimulation up to 120 dB. (v) High-resolution computed tomography (HRCT) of the temporal bones. (vi) Counseling and informed consent: parents and older patients were extensively informed of the potential advantages, disadvantages and risks associated with implantation to establish Acta Otolaryngol 2004; Suppl 552: 55  /63 # Taylor & Francis 2004. ISSN 0365-5237 DOI 10.1080/03655230410017148