Diagnostic part for qualification to implantation and  verification  of the settings after implantation


Diagnostics for a cochlear implant :

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It is estimated that the problem of hearing disorder affects about 12 % of the population. This is a significant medical and social problem. Hearing loss leads to a process of communicative disorders, limitations in daily life and work.

When hearing loss involves a child, leads to a delay in speech development, and thus, to disorders of cognitive and emotional area and delays in the general development. Every year 1-3 per 1000 children are born with hearing damage requiring early intervention, because only this way provides them proper development. The lack of adequate auditory stimuli in the form of ambient sounds and sounds of human speech interferes with the normal development of auditory and verbal language development in these children, and their overall development.

The bilateral profound sensorinerual hearing loss and deafness hearing aids generally do not benefit. Profound sensorineural hearing loss prevents  proper processing of acoustic signal even strengthened by the hearing aid, the only chance to return to the world of sound is the direct stimulation of the auditory nerve through the use of a cochlear implant . Initially, cochlear implants were intended only for adults who have lost their hearing after a period of development. Since the treatment safety was demonstrated, candidates for cochlear implants have also become children with congenital deafness .

In Poland, the first cochlear implant surgery was carried out in 1992 in the Department of Otolaryngology, Medical University of Warsaw. The operation was performed in an adult patient with bilateral profound sensorineural hearing loss. Over time and growing experience implantations of cochlear implants to children with bilateral deafness has begun.


Since then, this type of operation has become one of the very important methods of treatment used in our clinic. In order to provide the best care for our young patients we have created in the Department Children's Ward specially adapted to the needs of children and infants and their caregivers who are with the child throughout his stay in the hospital. Each year number of implanted cochlear implants in the Department grows and now under permanent care of Department of Otolaryngology, are more than 500 patients treated by this method.

 

Every child with confirmation in audiological examination of bilateral sensorineural hearing loss should be provided with two hearing aids and start auditory- verbal rehabilitation therapy under audiological and logopedic control immediately after discovery of the defect. If your child has a significant or profound hearing loss and limited or no benefit from hearing aids after six-month period , it should be referred to the procedure of qualification for treatment using cochlear implants.


Preoperative evaluation is an extremely important part of the healing process . Each potential candidate for a cochlear implant, both children and adults will be referred to the detailed qualification procedure in the Department consisting of interview, a precise audiological, aural, speech therapy, psychological and radiation assessment. If necessary, there are held consultations with other specialists (such as a pediatrician or cardiologist ).

 

Audiological evaluation

 

Audiological evaluation is one of the most important stages of the qualification. We are using the subjective and objective hearing  tests , including

 

  • pure tone audiometry
  • speech audiometry
  • audiometry in free field ( tonal and verbal )
  • impedance audiometry
  • otoacoustic emissions
  • auditory evoked potentials from the brainstem


A set of tests needed for qualification is chosen depending on the patient's age and the possibility of cooperation in the tests.

 

Logopedic evaluation

 

In speech we evaluate intensity of speech therapy so far, stage of speech development, the patient's willingness to communicate, the dominant channel in the perception of speech, family participation in the rehabilitation process, and the existence of potential or suspected central disorders that may affect the development of language.

 

Psychological evaluation

 

Psychological evaluation shall be based on observation, interview and psychological testing.

 

Imaging studies

 

The minimum requirements for a cochlear implant of the inner ear are: preserved bone of cochlea and cochlea connection with the auditory nerve. In order to assess the feasibility and potential obstacles to the placement of the multi-channel cochlear implant electrodes in the inner ear usually computed tomography (CT) of temporal bones s proceeded. Magnetic Resonance Imaging (MRI) is an additional examination used to explore the potential of cochleo – vestibular nerve disorders, or central nervous system disorders.

 

General qualification criteria

 

Candidates for cochlea implant prosthesis are patients with deep or significant bilateral sensorineural hearing loss who have limited or no benefits from hearing aids fitted properly. There should be no contraindication for the operation. It is also required approval of long-term rehabilitation program.

For children, an additional criteria is used which is delayed speech development and disproportionately small effects of a properly conducted auditory – speech rehabilitation. It is also necessary approval for the long-term rehabilitation of the family and the closest environment and the lack of medical contraindications for the operation.

In the case of cochlear implants very important are realistic expectations of patients and their families as a result of this treatment, depending on the number of additional factors that are presented individually to each patient clearly and understandably in the process of qualification in the Department. In children, this information is presented to their parents who are involved in the whole process of qualification.

Cochlear implantation is an beginning to the subsequent intensive and long-term auditory-speech rehabilitation and regular visits for results evaluation and control of settings parameters of cochlear implant sound processor. Encoding the processor’s signal is dependent on speech coding strategies. These strategies define how the audio signal is converted into electrical signals to stimulate the cochlear implant electrodes. The method of stimulation has to, in the maximum possible way, imitate a healthy working cochlea.

The rehabilitation process after the cochlear implantation is long and requires a lot of work on both sides - medical team consisting of an audiologist, speech therapist and psychologist, as well as on the side of the patient and his family. The effects of the rehabilitation are assessed during control visits, also then depending on the findings evaluating the progress of therapy and auditory training, we modify the settings of the speech processor parameters in cochlear implant and verify hearing aid settings for the other ear. In the case of bilateral implantation settings parameters are verified in both cochlear implants .

A very important step is to evaluate the benefits of the method of prosthetic hearing. Audiometric testing is performed in a free field with the cochlear implant and without it. Given the primary purpose of prosthetics, which is the improvement of communication with the environment through verbal communication, it is important to perform speech audiometry in free field. After carried out examinations verification of settings of cochlear implant parameters is performed.

 

Summation


Persons who are candidates for cochlear implantation should be referred to detailed examination undertaken by a multidisciplinary and experienced team and each patient should be treated individually, as it happens in Department of Otolaryngology Medical University of Warsaw. Only this allows for proper selection of patients in whom this method of treatment will achieve the expected auditory-speech benefits.

Cochlear implantation is an introduction to the subsequent intensive and long-term auditory-speech rehabilitation and regular visits for evaluation and control of the settings of cochlear implant sound processor parameters. After implantation of a cochlear implant patient remains under the care of the Cochear implants team in our clinic.

 

Magdalena Lachowska PhD, MD