Cochlear Osteoneogenesis After Meningitis in Cochlear Implant Patients

Abstract

Cochlear implants are the treatment of choice for auditory rehabilitation of patients with sensory deafness. They restore the missing function of Thomas Lenarz 1 inner hair cells by transforming the acoustic signal into electrical stimuli 1 Department of Otolaryngology, Head & Neck for activation of auditory nerve fibers. Due to the very fast technology development, cochlear implants provide open-set speech understanding Surgery, Hannover Medical School, Hannover, Germany in the majority of patients including the use of the telephone. Children can achieve a near to normal speech and language development provided their deafness is detected early after onset and implantation is performed quickly thereafter. The diagnostic procedure as well as the surgical technique have been standardized and can be adapted to the individual anatomical and physiological needs both in children and adults. Special cases such as cochlear obliteration might require special measures and re-implantation, which can be done in most cases in a straight forward way. Technology upgrades count for better performance. Future developments will focus on better electrode-nerve interfaces by improving electrode technology. An increased number of electrical contacts as well as the biological treatment with regeneration of the dendrites growing onto the electrode will increase the number of electrical channels. This will give room for improved speech coding strategies in order to create the bionic ear, i.e. to restore the process of natural hearing by means of technology. The robot-assisted surgery will allow for high precision surgery and reliable hearing preservation. Biological therapies will support the bionic ear. Methods are bio-hybrid electrodes, which are coded by stem cells transplanted into the inner ear to enhance auto-production of neurotrophins. Local drug delivery will focus on suppression of trauma reaction and local regeneration. Gene therapy by nanoparticles will hopefully lead to the preservation of residual hearing in patients being affected by genetic hearing loss. Overall the cochlear implant is a very powerful tool to rehabilitate patients with sensory deafness. More than 1 million of candidates in Germany today could benefit from this high technology auditory implant. Only 50,000 are implanted so far. In the future, the procedure can be done under local anesthesia, will be minimally invasive and straight forward. Hearing preservation will be routine.

Contralateral Implantation in Children Affected by Postimplant Meningitis

“…When meningitis is the cause of profound deafness, ossification has been reported in 34% of patients, of whom 67% were bilateral, and 13% had an asymmetric involvement and a variable timing of presentation [Durisin et al, 2010]. Cochlear ossification can start as early as 21 days after infection [Philippon et al, 2009] and continues over time with unpredictable speed [Durisin et al, 2010;Caye-Thomasen et al, 2012].…”

“…When meningitis is the cause of profound deafness, ossification has been reported in 34% of patients, of whom 67% were bilateral, and 13% had an asymmetric involvement and a variable timing of presentation [Durisin et al, 2010]. Cochlear ossification can start as early as 21 days after infection [Philippon et al, 2009] and continues over time with unpredictable speed [Durisin et al, 2010;Caye-Thomasen et al, 2012]. These outcomes have led to a general consensus that, once deafness has been confirmed, cochlear implantation should be performed bilaterally and immediately after the onset of meningitis [Cohen et al, P1 100 100 0 100 --100 -P2 100 50 60 10 70 50 10 50 P3 85 50 60 80 80 5 30 50 Recognition of bisyllabic phonetically balanced words in quiet and SNR +10, assessed prior to and after an average of 11.33 months postcontralateral implantation performed after piM.…”

“…Cochleostomy might require more extensive basal turn drilling [Rauch et al, 1997;Durisin et al, 2010] and cochlear fibrosis or ossification might prevent full electrode insertion [Mylanus and van den Broek, 2003;Philippon et al, 2009;Nichani et al, 2011]. Outcomes are less predictable, owing to local or central problems such as the following: incomplete depth of insertion or need of short/double arrays due to partial or complete cochlear ossification [Nichani et al, 2011]; direct damage to the spiral ganglion cells which might result in failure of the neuronal response even in full electrode insertions Nadol, 1997]; increased distance from neural structures due to fibrosis and ossification with unstable electric-neural interface [Nichani et al, 2011], and residua of the central nervous system with damage to the auditory pathways and cortex [Francis et al, 2004;Garcia et al, 2009;Nichani et al, 2011].…”

“…The role of meningitis on CI outcomes is recognized by some [Gantz et al, 1988;Cohen and Waltzman, 1993;Rauch et al, 1997;Rotteveel et al, 2005;Durisin et al, 2010;Nichani et al, 2011] but not all authors [Nikolopoulos, 2006]. In those studies where the degree of cochlear ossification was taken into account as one of the variables, poorer outcomes were described, mainly associated with partial insertion or use of alternative surgical procedures or electrodes [Gantz et al, 1988;Cohen and Waltzman, 1993;Rauch et al, 1997;Rotteveel et al, 2005;Nichani et al, 2011].…”

Cochlear Implants in Children: A Review

“…A significant difference between children with deafness caused by meningitis and that caused by the other viruses is that while CMV, toxoplasmosis and rubella are contracted perinatally, children who have had meningitis will have experienced sound prior to infection and may have developed some spoken language skills. A further complication of meningitis is ossification (bone growth) within the cochlea, which is usually bilateral and can commence within four weeks of the illness (Durisin et al, 2010). This makes it imperative that children who have had meningitis are diagnosed with hearing loss and receive cochlear implants as soon as possible, before ossification limits both the potential for a full insertion and for benefit.…”