Progress in cochlear implantation programs allows a better understanding of speech development in children with prelingual profound hearing loss. Less understood is the impact of vestibular receptor disorders which can be associated with congenital deafness. These disorders can be congenital or result from the surgical procedure. Sensory preservation surgical techniques are effective for residual hearing1-4 and have recently been proposed for preserving vestibular function. (CI Surgery Blog 12.5.16).
Also, measurements of vestibular function5-7, posture, and gait in these children has created a new area of interest, generating other questions, such as:
Recent studies from the Laboratory of Otoneurology, British Hospital, Department of Electrical Engineering, University Catolica Del Uruguay and Facultad de Medicina, Montevideo, Uruguay, demonstrate vestibular dysfunction in prelingual cochlear implant users and its impact on posture and gait. Postural control has been studied in a sample of children of different ages and times of implantation. Differences were found between cochlear implant users and children with normal hearing, in whom posture in different sensory conditions showed better performance when compared to the first group. Using regression curves related to both age and time of use of the cochlear implant, postural control showed a significant improvement with age and time of implant use.
Explaining these findings under the laws of the closed-loop control system was proposed as a first step, in which there is a re-weighting of sensory input, having visual and somatosensory information serving a major role in maintaining accurate posture. Over time and with use of the implant, the central nervous system modifies the gain of the sensory input (visual, vestibular, and somatosensory) to achieve a definitive adaptation process.8
Gait performance in implanted children was also assessed in conditions with the implant turned on and off.9 Impaired gait (lower gait velocity) was found with the implant turned on. This suggests that hearing works as a “dual task” for them. However, when the sample was divided into two groups of children, those who were implanted before and after 3 years old, the gait performance in the earlier implanted children was similar to that of the children with normal hearing. These findings suggest that auditory input is not neutral in the progress of motor skills, and like in speech production, the interaction between auditory information and motor performance during the first years of childhood are crucial for a suitable neurodevelopment.
The new findings seem to confirm the importance of less traumatic surgical procedures to avoid vestibular damage and implantation at the earliest stages of neurodevelopment are precise strategies to improve both speech and motor skills development in children with profound prelingual deafness.
1. Boggess WJ, Baker JE, Balkany TJ. Loss of residual hearing after cochlear implantation. Laryngoscope. 1989 Oct;99(10 Pt 1):1002-5.
2. Kautzky M, Susani M, Hübsch P, Kürsten R, Zrunek M. Holmium: YAG laser surgery in obliterated cochleas: an experimental study in human cadaver temporal bones. Eur Arch Otorhinolaryngol. 1994;251(3):165-9.
3. Klenzner T, Knapp FB, Schipper J, Raczkowsky J, Woern H, Kahrs LA, Werner M, Hering P. High precision cochleostomy by use of a pulsed CO2 laser - an experimental approach. Cochlear Implants Int. 2009;10 Suppl 1:58-62.
4. Eze N, Jiang D, Fitzgerald, O'Connor A. Inner ear energy exposure while drilling a cochleostomy. Acta Otolaryngol. 2014 Nov;134(11):1109-13.
5. Frounlund J, Harder H,Maki-Torkko E, Ledin T. Vestibular Function after Cochlear Implantation: A Comparison of Three Types of Electrodes.Otol Neurotol 2016 37(10)1535-1540.
6. Wolter NE, Cushing SL,MadrigalLD,James Al,Campos J, Papsin BC,Gordon KA.Unilateral Hearing Loss Is Associated With Ipaired Balance in Children.: A PIlot Study. Otol Neurotol 2016.37(10) 1589-1595.
7. Inoue A, Iwasaki S, Ushio M, Chihara Y, Fujimoto C, Egami N, Yamasoba T. Effect of Vestibular Dysfunction on the development of gross motorfunction in children with profound hearing loss. Audiol Neurotol 2013: 18(3) :143-151.
8. Suarez H, Ferreira E, Alonso R, Arocena S, San Roman C,Herrera T,Lapilover V.Acta Otolaryngol. 2016; 136(4):344-350.
9. Suarez H, Alonso R, Arocena S, Ferreira E, San Roman C, Suarez A, Lapilover V. Sensorymotor interaction in deaf children.Relationship between gait performance and hearing input during childhood assessed in prelingual cochlear implant users. Acta Otolaryngol.2016.15:1-6.
Guest Author: Hamlet Suarez, MD
Chairman, Laboratory of Otoneurology
British Hospital, Biomedical Engineering Program