Development of objective balance tests in newborns and young children

Postural control is a dynamic process involving the integration of visual, vestibular and somatosensory input information to the cerebellum. These sensory systems acquire their ultimate function in various ages. The vestibular organ is the first sensory organ to develop in humans, and the vestibular nerve is the first cranial nerve to complete myelination, making the vestibular system functional at birth. The vestibular function maintains spatial orientation and gaze stabilisation during motion, and it is essential for normal motor development in babies and toddlers. Vestibular failure in early life is associated with decreased muscle tone and suboptimal motor proficiency later in life. It is also associated to unprecedented falls, decreased spatial awareness and reading difficulties. In children with profound sensorineural hearing loss, vestibular impairment is common, and the demand for vestibular assessment has increased in various clinical contexts. Although we have sophisticated methods to assess the vestibular system in the adult population, the clinical approach to the vestibular system in infants and young children has been hampered by the lack of a structured, age- appropriate methodology. The aim of this thesis was to develop, apply and evaluate reliable test protocols for vestibular impairment in newborns and young children because this is a patient group which tends to be underrepresented due to the challenges in their clinical management. This PhD project includes four studies conducted at the Audiology and Neurotology Department of Karolinska University Hospital between 2019 and 2025. Study I established the feasibility of Bone-Conducted cervical Vestibular- Evoked Myogenic Potentials (BCcVEMP) in infants, alongside the universal hearing screening programme of our hospital. Fifty infants who did not pass the hearing screening were recruited and tested with BCcVEMP. Outcomes showed high test completion (87%) and measurable responses in 73% of the tested ears. Study II investigated the vestibular function in young children with a radiologically confirmed vestibulocochlear nerve aplasia or hypoplasia before cochlear implantation (CI). The patients were tested with BCcVEMP, video Head Impulse Test (vHIT) and mini-ice-water caloric tests. Residual function with present vestibular responses were found in 57% of the tested ears. This predicts a better auditory outcome following CI and indicates a link between auditory and vestibular pathway integrity. Study III investigated the long-term vestibular function in 38 CI recipients. These patients were operated early in life with bilateral Cis. The study focusing on the vestibular function was part of the Teenage and Young Adults with Cochlear Implants (TAYACI). All five parts of the vestibular system were tested: three canals and two sacs in each ear; vHIT and BC cervical and ocular VEMPs showed the most robust responses. Vestibular impairment was detected in approximately half of the tested ears (46%- 55%). Study IV explored the reliability of BCcVEMP in 53 infants tested early after birth and retested at one year of age. Reproducible responses were obtained in 73% of the tested ears in infancy and in 94% at the follow-up with a positive predictive value of 95%. Across all studies the BCcVEMP was shown to be feasible, reliable and well tolerated. The combination of BCcVEMP and vHIT of lateral canals (at the earliest age compatible with reliable testing) assessed the vestibular end-organ function and provided additional information on the vestibular nerve pathway integrity. The findings show that vestibular function can be measured from birth onwards by employing the method or methods best suited to the patient's age. Long- term vestibular follow-up confirmed that impairment persists in certain diagnostic groups for example Usher syndrome and patients affected by congenital cytomegalovirus. The dissertation thesis establishes the feasibility and reliability of BCcVEMP as a test method for vestibular screening in newborns at risk for vestibular impairment. In conclusion, BCcVEMP and vHIT form an effective test battery for the comprehensive evaluation of the vestibular system in children. List of scientific papers I. Methodological aspects of testing vestibular evoked myogenic potentials in infants at universal hearing screening program. Verrecchia L, Karpeta N, Westin M, Johansson A, Aldenklint S, Brantberg K, Duan M. Sci Rep. 2019;9(1):17225. https://doi.org/10.1038/s41598-019-53143-z II. Vestibular function in children with vestibulocochlear nerve aplasia/hypoplasia. Karpeta N, Asp F, Edholm K, Bonnard Å, Wales J, Karltorp E, Duan M, Verrecchia L. Acta Otolaryngol. 2023;143(10):861-6. https://doi.org/10.1080/00016489.2023.2285453 III. Long-Term Follow-Up of Vestibular Function in Cochlear-Implanted Teenagers and Young Adults. Karpeta N, Karltorp E, Verrecchia L, Duan M. Audiol Res. 2025;15(2). https://doi.org/10.3390/audiolres15020042 IV. Reliability of Bone-conducted cervical Vestibular-Evoked Myogenic Potentials in newborns: a prospective study. Karpeta N., Verrecchia L., Duan M. [Submitted]