The latest medical research on Otolaryngology

Studies investigating the relationship between initial electrophysiological thresholds and subsequent behavioural hearing thresholds have demonstrated uncertainty as to whether initial results can provide an accurate estimation of an infant's functional hearing. This estimation must be accurate if a cochlear implant (CI) is to be considered before behavioural audiometry.This study aims to explore the variance between initial electrophysiological thresholds and subsequent behavioural hearing thresholds in infants to determine under which conditions electrophysiological results can be used to support a CI recommendation before behavioural audiology.

This is a prospective cohort study of 63 infants with suspected severe to profound hearing loss, referred to the Cochlear Implant Clinic, Melbourne, before 12 months of age. The assessment protocol includes auditory brainstem response, auditory steady state response, tympanometry, and behavioural audiometry.

For most infants undergoing CI candidacy evaluation, initial electrophysiological thresholds are an accurate reflection of their subsequent behavioural thresholds. An alternative CI candidacy pathway is recommended for infants who show profound sensorineural hearing loss on initial electrophysiological testing, in the absence of middle ear effusion, prematurity, or auditory neuropathy features, to provide CI recommendations before behavioural thresholds are obtained. This would lead to reduced delay to implantation and improved oral language outcomes.

We report an unusual case of cochlear implant complication and eventual explantation secondary to an allergic reaction to silicone.

A 62-year-old man who underwent cochlear implantation for asymmetric hearing loss developed an allergic response to the implant within a few weeks of the surgery. This led to subsequent explantation. Patch testing using the various parts of the implant revealed a hypersensitive response to the silicone component of the receiver stimulator. There have only been 6 reported cases of cochlear implant explantation secondary to allergic reactions to cochlear implants. The inflammatory reaction has been to the silicone component of the cochlear implant found in the silicone used in Cochlear America's implants.

Although rare, it's important to be aware of delayed hypersensitivity reactions to the silicone component of a cochlear implant. Attention should be made to associate symptoms such as pruritis, urticaria and loss of hair as symptoms and signs of possible allergic reaction to the implanted component. Steroids may help to alleviate symptoms; however, symptoms have been shown to recur after cessation of steroids. Treatment requires the removal of the device.

Hearing implants often limit the assessment of magnetic resonance examinations due to susceptibility artefacts. Our aim was to evaluate the impact of artefacts attributed to the Osia®2 implant system in terms of utility in visualizing selected cranial structures.

A BI300 implant and an OSI200 actuator were implanted into a human cadaver head in the audiologically most favourable position according to the manufacturer's guidelines. Scanning was accomplished using the institutional head and inner ear protocol with a General Electric 1.5 Tesla scanner with retained and removed implant magnet, extended with T1 and T2 weighted sequences with metal-artefact reduction (MAVRIC SL). Image quality was evaluated by three radiologists.

The Osia®2 produced significant artefacts in most of the series of standard imaging sequences predominantly on the ipsilateral side of the head. The majority of the artefacts were caused by the implant magnet. Even without removing the magnet, MAVRIC SL improved image quality to such an extent that it became comparable with that after magnet removal.

The standard sequences suffer considerable quality loss due to the artefacts, attributed predominantly to the magnetic component. Metal-artefact reduction sequences are effective in obtaining sufficient-to-good quality images without surgical magnet removal.

The implantation of biohybrid electrodes was introduced a few years ago in our clinic. These electrodes coated with autologous mononuclear cells releasing anti-inflammatory and neuroprotective factors are thought to reduce insertion trauma and maintain the vitality of surviving spiral ganglion neurons. The clinical feasibility of this approach has already been demonstrated. In the present retrospective study, the four-year results of the two sides (classical electrode and biohybrid electrode) in the bilaterally implanted patients were compared in order to investigate possible adverse long-term effects.

All patients received a complete audiological diagnosis which also included a speech audiogram and impedance measurement. The measurements were carried out 1 month, 3 months, 6 months, 1 year, 2 years, 3 years and 4 years after implantation. The hearing results were assessed by pure tone audiometry.

All patients showed satisfactory speech understanding and similar impedances on both sides although they had a long-term deafness before implantation of the side provided with a biohybrid electrode array. The results of speech understanding and impedance measurements were stable for years. Cone beam computed tomography was performed in 4 patients three years after implantation and could rule out cochlear ossification. Other complications were also not registered in any of the patients.

Due to satisfactory outcomes and lack of complications, the biohybrid electrode is considered to be a safe option in cochlear implantation. The simplicity of application of autologous cells as a source of anti-inflammatory and neuroprotective factors via a biohybrid electrode array is a key step for cell-based, regenerative therapies for deafness.