Bilateral globus pallidus internus deep brain stimulation for dyskinetic cerebral palsy supports success of cochlear implantation in a 5-year old ex-24 week preterm twin with absent cerebellar hemispheres.

BACKGROUND: Early onset dystonia (dyskinesia) and deafness in childhood pose significant challenges for children and carers and are the cause of multiple disability. It is particularly tragic when the child cannot make use of early cochlear implantation (CI) technology to relieve deafness and improve language and communication, because severe cervical and truncal dystonia brushes off the magnetic amplifier behind the ears. Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) neuromodulation can reduce dyskinesia, thus supporting CI neuromodulation success. METHODS: We describe the importance of the order of dual neuromodulation surgery for dystonia and deafness. First with bilateral GPi DBS using a rechargeable ACTIVA-RC neurostimulator followed 5 months later by unilateral CI with a Harmony (BTE) Advanced Bionics Hi Res 90 K cochlear device. This double neuromodulation was performed in series in a 12.5 kg 5 year-old ex-24 week gestation-born twin without a cerebellum. RESULTS: Relief of dyskinesia enabled continuous use of the CI amplifier. Language understanding and communication improved. Dystonic storms abated. Tolerance of sitting increased with emergence of manual function. Status dystonicus ensued 10 days after ACTIVA-RC removal for infection-erosion at 3 years and 10 months. He required intensive care and DBS re-implantation 3 weeks later together with 8 months of hospital care. Today he is virtually back to the level of functioning before the DBS removal in 2012 and background medication continues to be slowly weaned. CONCLUSION: This case illustrates that early neuromodulation with DBS for dystonic cerebral palsy followed by CI for deafness is beneficial. Both should be considered early i.e. under the age of five years. The DBS should precede the CI to maximise dystonia reduction and thus benefits from CI. This requires close working between the paediatric DBS and CI services.

Cochlear implantation in children with sickle cell disease.

Sickle cell disease (SCD) is associated with sensorineural hearing loss (SNHL). Although the hearing loss is usually mild, some develop severe-to-profound hearing loss, in whom cochlear implants (CI) may be an option. We present the cases of two children with SCD who developed bilateral severe-to-profound SNHL and underwent cochlear implantation. One patient became profoundly deaf after an acute episode of dizziness. Imaging indicated bilateral cochlear ossification, making subsequent cochlear implant surgery challenging. The second patient developed bilateral severe-to-profound SNHL following acute vaso-occlusive crises. She went on to have uncomplicated cochlear implant surgery. These cases illustrate the variable manner in which children with SCD may develop SNHL, and the difficulties associated with managing such cases. We recommend that children with SCD should undergo regular audiological assessment. Furthermore, clinicians should be aware of the risk of cochlear fibrosis and ossification and ensure prompt assessment following an acute vaso-occlusive crisis or unexplained vestibulocochlear event.

Inner ear energy exposure while drilling a cochleostomy.

CONCLUSION: Drilling a cochleostomy exposes the cochlea to acoustic and mechanical trauma, particularly during the final stage when the running burr is in contact with an intact membranous labyrinth that is then breached. To minimize cochlear damage we recommend avoidance of prolonged contact of the running burr with the membranous labyrinth. The promontory should be drilled until a thin eggshell of bone remains that can be removed with microinstruments, thus allowing the atraumatic opening of the membranous labyrinth with a sharp instrument. OBJECTIVES: To determine the energy transmitted to the inner ear while drilling a cochleostomy. METHODS: Eight human cadaveric temporal bones were used. Stapes velocity as measured with the laser Doppler vibrometer was used as a reflection of energy input to the cochlea. Measurements were taken during the different stages of cochleostomy formation using a 1 mm diamond burr: drill on promontory, edge of the fenestration, blue-lined fenestration, membranous labyrinth and through the membranous labyrinth. RESULTS: Drilling the promontory in preparation for the cochleostomy causes minimal energy transmission into the cochlea. There is significant and marked cochlea energy transfer when the running burr touches the membranous labyrinth and enters the scala tympani of a magnitude similar to touching the incus.

European multi-centre study of the Nucleus Hybrid L24 cochlear implant.

OBJECTIVES: To investigate the preservation of residual hearing in subjects who received the Nucleus Hybrid L24 cochlear implant. To investigate the performance benefits up to one year post-implantation in terms of speech recognition, sound quality, and quality of life. DESIGN: Prospective, with sequential enrolment and within-subject comparisons. Post-operative performance using a Freedom Hybrid sound processor was compared with that of pre-operative hearing aids. STUDY SAMPLE: Sixty-six adult hearing-impaired subjects with bilateral severe-to-profound high frequency hearing loss. RESULTS: Group median increase in air-conduction thresholds in the implanted ear for test frequencies 125-1000 Hz was < 15 dB across the population; both immediately and one year post-operatively. Eighty-eight percent of subjects used the Hybrid processor at one year post-op. Sixty-five percent of subjects had significant gain in speech recognition in quiet, and 73% in noise (≥ 20 percentage points/2 dB SNR). Mean SSQ subscale scores were significantly improved (+ 1.2, + 1.3, + 1.8 points, p < 0.001), as was mean HUI3 score (+ 0.117, p < 0.01). Combining residual hearing with CI gave 22-26 %age points mean benefit in speech recognition scores over CI alone (p < 0.01). CONCLUSIONS: Useful residual hearing was conserved in 88% of subjects. Speech perception was significantly improved over preoperative hearing aids, as was sound quality and quality of life.

Evaluation of round window accessibility to cochlear implant insertion.

Emphasis on hearing preservation has led to recognition of the round window membrane (RWM) as a portal for the cochlear implant electrode array. The St Thomas' Hospital (STH) classification was devised to evaluate the accessibility of RWM electrode insertion. The objectives of this study were: (1) to prospectively evaluate the STH classification in selecting the appropriate cochlear insertion route in "RWM-intentioned" cases, and (2) to ascertain if RWM accessibility differs from adults to children. This was a prospective cohort study of consecutive patients (adult and paediatric) undergoing cochlear implantation at a specialist auditory implant centre. Visibility of the RWM was graded according to the STH classification after an "optimal" posterior tympanotomy had been performed and any overhang of the bony round window niche removed without breaching the RWM. Most adult (89 %) and paediatric (78 %) cases had more than 50 % of the RWM exposed (Types I and IIa). Cases having less than 50 % of RWM exposed (Types IIb) or none exposed (Type III) were twice as common in children (p = 0.004). 96 % of Type I and 63 % of Type IIa cases underwent RWM insertion through a membranous cochleostomy. 71 % of Type IIb necessitated an extended membranous cochleostomy. All Type III cases required a conventional bony cochleostomy. When more than 50 % of RWM was visible (Types I and IIa), 88 % underwent a membranous cochleostomy. For "RWM-intentioned" cases, the STH classification can be a sensible method of relating RWM visibility/accessibility to the optimal route for insertion. This study also demonstrates that RWM insertion is more challenging in children.

Round window electrode insertion potentiates retention in the scala tympani.

CONCLUSIONS: The round window membrane (RWM)-intentioned approach is superior to the traditional bony cochleostomy (BC) approach in obtaining electrode placement within the scala tympani (ST). OBJECTIVE: Cochlear implant outcome is influenced by several factors, including optimal placement and retention of the electrode array within the ST. The present study aimed to assess whether the RWM route is superior to a traditional BC for placement and retention of the electrode array in the ST. METHODS: This was a prospective consecutive non-randomized comparison study. All patients were implanted with the Advanced Bionics 1J electrode array. The RWM approach (n = 32) was compared with a traditional BC group (n = 33). The outcome measure was the electrode position as judged within the scalar chambers at four points along the basal turn using postoperative computed tomography (CT). RESULTS: When the mean position scores were compared, the RWM-intentioned group had significantly more electrodes directed towards the ST compartment than the BC group (p < 0.001). The RWM electrodes achieved 94% ST retention compared with 64% for the BC group (p < 0.05). All electrodes stayed in the ST in the RWM group, whereas in the BC group 9% crossed from the ST to the scala vestibuli.

Hearing preservation surgery: current opinions.

BACKGROUND/AIMS: Although the indications and surgical technique for cochlear implantation are well formalized, the introduction of hearing preservation surgery and electric acoustic stimulation have posed new questions for the cochlear implant clinician. This study was designed to crystallize the contemporary views of the implant community on how best to implement these new strategies. METHOD: An anonymized questionnaire was made available to members of the Politzer Society and a selected group of implant surgeons via the Internet. Five questions required the respondent to choose a specific answer from the text on technique and 17 questions assessed the relative importance attached to the statements relating to the surgical process. A final question inquired on what basis the opinions were derived. The country of origin was also identified. RESULTS: The questionnaire was sent to 180 clinicians of whom 62 replied (34%). Tacit agreement was obtained in 2 of the specific questions and in 10 of the relative importance inquiries. There were varying degrees of opinions on the remaining questions. CONCLUSION: It is clear that there is still limited consensus between surgeons when considering ways of maximizing outcomes in hearing preservation surgery and electric acoustic stimulation. More protocol-driven studies are required before an accepted gold standard approach can be achieved.