Optimization of Cochlear Implant MAP-parameters in Children
Condition: Cochlear Implants; Evoked Potentials, Auditory; Child; Disabilities Hearing; Deafness; Hearing
MeSH terms: Deafness
Study type: Interventional

Summary: 
      This project will complete a long-term follow up for children that have received cochlear
      implants (CI) early in life and had their CI's programmed based on objective measurements.

      At Sahlgrenska University Hospital in Gothenburg, generally, all younger children (0-3
      years), the last ten years, had their CI's programmed based on objective measurements. The
      programming of the CI carried out during the first year after the surgical insertion is done
      on the foundation of the objective measurements and is generally what the child will live
      with thereafter. This method also seem to be close to other clinics in Sweden and the rest of
      the world, however, there are no specific guidelines regarding the how the programming of the
      CI is to be carried out on small children. To this date there are no studies, to our
      knowledge, that have confirmed the validity of using these objective measurements and if it
      is the best for the child. We therefore aim to do a long term follow up on children that have
      received CI and programmed this way, and study if there would be beneficial to redo the
      programming when the child is old enough to actively participate.

      The aim with this project is evaluate how suitable it is to mainly use objective measurements
      when programming the cochlear implant and, in addition to this, examine if the children's
      hearing can be improved if the programming is based on the behavioral measurements of sound
      when the children are old enough to participate in such. It will examine what happens with
      the end result if the programming foundation differentiates from one another; if there are
      any measurable differences in hearing skills.

      The result from this project expects to generate knowledge that is highly important for those
      working with small children receiving CI's, and by extension it will benefit the children
      that rely on this device in there every day life.
    

Detailed description: 
      Cochlear implants (CI) enable hearing for persons who otherwise would have been deaf. A CI
      substitutes the sensory cells in the cochlea and stimulates the auditory nerve directly with
      weak electrical pulses. For children born deaf, or become deaf at an early age, prompt
      detection of this condition is important to since it enables the possibility of an early
      implantation of the CI and facilitates the child's development of a spoken language. When it
      comes to detecting deafness in newborns, Sweden has a well-functioning and widespread hearing
      screening program for infants, permitting children born deaf, or with severe hearing
      impairments, to be discovered very early. In general, children that are born deaf can get a
      CI implanted at about one year of age, if there are no other contraindications.
      Internationally it has become increasingly common for implants to be inserted at even lower
      ages, sometimes even as young as five months of age.

      For small children who receive CI's at an early age it is not possible to perform
      measurements based on the child making subjective assessments of how the sound is perceived
      when the electrical stimulation is altered through the implant. Also, small children cannot
      judge and report back the quality of the sound. Instead, objective measurements are commonly
      used since they do not require the active participation of the child, along with observations
      of the child and how it spontaneously reacts to the sound stimulation. A common objective
      measurement is to find the lowest level of electrical stimulation required to obtain a
      response from the auditory nerve, i.e. the electrically evoked action potential (ECAP)
      threshold. The CI manufacturer Cochlear Ltd has developed an automatic system for this
      measurement. Based on such measurements, as the automatic ECAP-measurement, the electrical
      stimulation from the implant can adjusted to the so-called MAP, where the minimum and maximum
      stimulation levels (T- respectively C-levels) are set for each individual electrode on the
      implant to create the dynamic range of electrical stimulation. This MAP then becomes the
      basis for the child's ability to perceive sound.

      Clinically, today (at Sahlgrenska University Hospital, Gothenburg, Sweden) a basic
      programming of the MAP is performed based on ECAP measurements, after which adjustment of
      only the overall level is carried out based on the child's reactions. However, no subjective
      measurement is made regarding threshold levels of stimulation through the implant or that the
      child actually perceives medium sound equally across the different channels. When the child
      can participate in sound field audiometry, adjustments of the MAP settings are made to get a
      straight audiogram, but basically, the children continue to use the setting based on the ECAP
      measurement. Adult patients with acquired deafness receiving CI are managed in a different
      manner than the children. The programming of the implant for adults is based on subjective
      measurements of how stimulation via individual electrodes is perceived. By measuring
      thresholds for individual electrodes, i.e. minimum audible stimulation (T-levels) and levels
      where stimulation is immediately below unpleasant strong (C-levels), then the MAP is
      programmed with an individual dynamic range for each electrode.

      To our knowledge no previous study have explored how the MAP based on an ECAP measurement
      endures over time or if a re-programming should be carried out when the child reliably can
      participate in behavioral measurements, which is about seven years of age in terms of
      measuring T-levels. Studies have shown that there is a correlation between ECAP-thresholds
      and T- and C-levels for people who can participate actively. However, the relationship is
      relatively weak and some researchers have even considered it too weak for ECAP thresholds to
      be the basis for programming the implant. However, in most clinics, these thresholds are used
      as a basis for programming CI to small children.

      Several of those who work with programming the MAP in small children claims to witness an
      adaptation in sensitivity of the auditory nerve to the applied stimulation; indicating that
      the results of the objective measurement could gradually change if there is an alternation in
      stimulation levels. However, there are no studies at this time that neither confirm nor deny
      this.

      The aim of this project is to investigate and clarify how children who receive CI at an early
      age should be monitored and to evaluate the objective ECAP measurement as a basis for setting
      stimulation levels. It also aims to investigate if there is any change in the result of the
      ECAP measurement after adjustment has been made in the MAP. After completion of the study,
      the goal is to offer a better and more knowledge-based (re-) habilitation for children who
      receive CI's, for whom there are currently no definite guidelines for programming and
      follow-up.
    

Intervention name(s): Re-programming of cochlear implant
Intervention type(s): Other
Intervention description(s): New MAP based on behavioral T- and C-levels
Intervention model: Single Group Assignment
Intervention model description: Single-case research design
Masking: None (Open Label)
Primary purpose: Supportive Care