Amy P. Olund

C. Lane Anzalone

Matthew L. Carlson

Sarah Nuhanovic

Case Reports in Medicine

Introduction. Charcot-Marie-Tooth (CMT) disease is a peripheral hereditary neuropathy associated with motor and sensory impairment and can result in profound sensorineural hearing loss (SNHL). Currently, the role of cochlear implantation in the setting of CMT and other progressive peripheral neurodegenerative disorders is not well established. Methods. Case report and review of the English literature. Results. A 70-year-old male with CMT was referred for evaluation of progressive asymmetric SNHL and reported a 15-year duration of deafness involving the left ear. Audiometric testing confirmed profound SNHL in the left ear, while the right ear exhibited moderate-to-severe SNHL. Left-sided cochlear implantation was performed using a conventional length lateral wall electrode. Intraoperative device testing found normal impedance levels throughout the array; however, electrically evoked auditory potentials were absent on all electrodes. Upon initial activation 3 weeks after surgery, the patient reported excellent access to sound in the cochlear implant-only condition. He has made good progress at each subsequent visit; speech perception testing after seven months showed improvement from 0% to 32% on AzBio sentence and 53% on CNC phoneme testing in the cochlear implant-only condition. Conclusion. We report the third case of cochlear implantation in a patient with CMT. SNHL in CMT is hypothesized to result from disruption of synchronous activity of the cochlear nerve. In patients with CMT, cochlear implantation may reconstitute synchronous neural activity by way of supraphysiological electrical stimulation. Our results corroborate two earlier reports that cochlear implantation is a viable option for rehabilitation of SNHL in this unique subset of patients.</jats:p

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Case ReportCochlear Implantation in Charcot-Marie-Tooth Disease:Case Report and Review of the LiteratureC. Lane Anzalone ,1 Sarah Nuhanovic,2 Amy P. Olund,3 and Matthew L. Carlson11Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN, USA2Department of Laboratory and Research, Mayo Clinic, Rochester, MN, USA3Department of Audiology, Mayo Clinic, Rochester, MN, USACorrespondence should be addressed to C. Lane Anzalone; anzalone.charles@mayo.eduReceived 18 October 2017; Accepted 8 March 2018; Published 26 March 2018Academic Editor: Andre´ Me ́garbane ́Copyright © 2018 C. Lane Anzalone et al.'is is an open access article distributed under theCreative CommonsAttribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Introduction. Charcot-Marie-Tooth (CMT) disease is a peripheral hereditary neuropathy associated with motor and sensoryimpairment and can result in profound sensorineural hearing loss (SNHL). Currently, the role of cochlear implantation in thesetting of CMT and other progressive peripheral neurodegenerative disorders is not well established. Methods. Case report andreview of the English literature. Results. A 70-year-old male with CMT was referred for evaluation of progressive asymmetricSNHL and reported a 15-year duration of deafness involving the left ear. Audiometric testing conﬁrmed profound SNHL in theleft ear, while the right ear exhibited moderate-to-severe SNHL. Left-sided cochlear implantation was performed using a con-ventional length lateral wall electrode. Intraoperative device testing found normal impedance levels throughout the array;however, electrically evoked auditory potentials were absent on all electrodes. Upon initial activation 3 weeks after surgery, thepatient reported excellent access to sound in the cochlear implant-only condition. He has made good progress at each subsequentvisit; speech perception testing after seven months showed improvement from 0% to 32% on AzBio sentence and 53% on CNCphoneme testing in the cochlear implant-only condition. Conclusion. We report the third case of cochlear implantation ina patient with CMT. SNHL in CMT is hypothesized to result from disruption of synchronous activity of the cochlear nerve. Inpatients with CMT, cochlear implantation may reconstitute synchronous neural activity by way of supraphysiological electricalstimulation. Our results corroborate two earlier reports that cochlear implantation is a viable option for rehabilitation of SNHL inthis unique subset of patients.1. IntroductionCharcot-Marie-Tooth (CMT) disease is a clinically andgenetically heterogeneous group of disorders aﬀecting theperipheral nervous system. 'e disease can manifest inprofound SNHL, hypothesized to result from disruption ofsynchronous activity of the cochlear nerve. Given that CMTaﬀects the retrocochlear auditory pathway, there have beentheoretical concerns that CI is incapable of providingmeaningful auditory stimulation. Two previous cases of CIin patients with CMT have been described in the worldliterature; thus, the role of cochlear implants in auditoryrehabilitation of CMT-associated SNHL is poorly deﬁned[1, 2]. We present a patient with CMT-associated deafnesssuccessfully treated with cochlear implantation.2. Case PresentationA 70-year-old male with CMT was referred for evaluation ofprogressive asymmetric SNHL and reported a 15-year du-ration of deafness involving the left ear. He was initiallya bilateral hearing aid user but subsequently stopped using hishearing aid in the left ear several years prior due to experi-encing progressive audiometric decline. Audiometric testingconﬁrmed profound SNHL in the left ear, while the right earexhibited moderate-to-severe SNHL. Information regardingthe subtype of his CMT is unavailable at our tertiary carefacility; prior workup was performed at another institution.Left-sided cochlear implantation was performed usinga conventional length lateral wall electrode. 'e electrodeswere introduced without resistance, and a full insertion wasHindawiCase Reports in MedicineVolume 2018, Article ID 1760978, 3 pageshttps://doi.org/10.1155/2018/1760978achieved using the MED-EL™ Synchrony Flex® 28 cochlearimplant. Intraoperative device testing found normal im-pedance levels throughout the array; however, electricallyevoked auditory potentials were absent on all electrodes.Upon initial activation 3 weeks after surgery, the patientreported excellent access to sound in the cochlear implant-only condition. He has made good progress at each sub-sequent visit; speech perception testing after seven monthsshowed improvement from 0% preoperatively to 32% onAzBio sentence and 53% on CNC phoneme testing in thecochlear implant-only condition. At an 18-month phonefollow-up, he reports improving subjective beneﬁt andconsistent usage of the device.3. DiscussionCharcot-Marie-Tooth disease is the most commonly oc-curring hereditary motor and sensory neuropathy. CMTcanbe classiﬁed as types 1 to 7, X, and intermediate, with manysubtypes. CMT is genetically heterogeneous with more than30 genes identiﬁed to date. Despite this, the vast majority ofcases are attributed to mutations in just four of these genes:PMP22, MPZ, GJB1, and MFN2. CMT types 1 and 2 rep-resent by far the largest proportion of patients; these clas-siﬁcations are based oﬀ features of demyelinating (CMT1) oraxonal (CMT2) dysfunction. Motor weakness is the pre-dominant symptom, typically arising in the ﬁrst or seconddecade of life.'emajority of treatment options are directedtowards alleviation of motor deterioration; there have beenfew reports describing the management of hearing loss inpatients with CMT [3].Hearing loss in patients with CMT is associated withpoint mutations or deletions in the peripheral myelinprotein (PMP) 22 gene, a myelin regulatory gene [4]. Neuralconduction abnormalities in the auditory pathway lead tothe auditory deﬁcits seen in individuals with CMT. Whilethe exact pathogenesis of deafness in CMT patients is un-certain, it has been proposed that the resultant SNHL isa consequence of retrocochlear dysfunction. 'e failure todetect auditory brainstem responses is theorized to resultfrom the loss of discharge synchrony secondary to de-myelination or axonal disruption of the cochlear nerve [5, 6].Traditionally, retrocochlear disease aﬀecting the auditorypathway has been considered a contraindication to CI. Inpatients with auditory neuropathy spectrum disorder(ANSD), there is an absence of auditory brainstem responsesdespite the intact outer hair cell function. ANSD results inpoor speech discrimination while general awareness of speechis often retained.'e resultant severe impairment in temporalprocessing ability was originally thought to be unchanged byCI; however, over the last decade, we have seen several diseaseprocesses that have challenged this notion. Speciﬁcally, it iswell documented that many patients with auditory nervehypoplasia, auditory neuropathy, and acoustic neuroma withan intact cochlear nerve gain signiﬁcant beneﬁt fromCI [7, 8].In patients with CMT, cochlear implantation may reconsti-tute synchronous neural activity by way of supraphysiologicalelectrical stimulation, thus improving speech discriminationscores.Two prior cases of cochlear implantation in patients withSNHL attributed to CMT have been reported in the worldliterature [1, 2]. Each demonstrated improvements in speechdiscrimination scores. 'e improvement progression wasnoted to be slower than in the typical subset of patients re-ceiving CI; however, signiﬁcant beneﬁt was eventually re-alized. Goswamy et al. described a 67-year-old male withCMT-attributed SNHL who underwent CI. Open-set speechdiscrimination (BKB sentences) scores were obtained at 1week, 3 months, 9 months, and 21months after activation andwere noted to be 0, 0, 53, and 54%, respectively. Postelmanset al. described a 53-year-old female with CMT who ﬁrstexperienced a progressive hearing loss at 8 years of age; shehad worn hearing aids for 25 years prior to undergoing CI. At6 months postoperatively, she had improved to 59% worddiscrimination at 60 dB from preoperative discrimination of50% at 75 dB. In our patient, similar ﬁndings were observed.We attribute his initial absent evoked auditory potentials tohis extent and duration of deafness. A gradual improvementhas been noted with each subsequent visit, and the patient hasbeen pleased with his progress to date. It is important to notethat his duration of deafness (15 years) should also be con-sidered when evaluating his rate of progress.4. ConclusionWe report the third case of cochlear implantation in a pa-tient with CMT. Improvement of speech discrimination inthis unique subset of patients has been shown to occur ata more gradual rate of progression. While no deﬁnitiverecommendations concerning the eﬃcacy of CI in patientswith CMT have been established, our results corroboratetwo earlier reports that cochlear implantation is a viableoption for rehabilitation of SNHL in CMT patients. Futurestudy should be performed in an attempt to further deﬁnethe role of CI in the setting of CMT.Conflicts of Interest'e authors declare that they have no conﬂicts of interest.References[1] J. Goswamy, I. A. Bruce, K. M. Green, and M. P. O’Driscoll,“Cochlear implantation in a patient with sensori-neuraldeafness secondary to Charcot-Marie-Tooth disease,” Co-chlear Implants International, vol. 13, no. 3, pp. 184–187, 2012.[2] J. T. Postelmans and R. J. Stokroos, “Cochlear implantation ina patient with deafness induced by Charcot-Marie-Toothdisease (hereditary motor and sensory neuropathies),” Jour-nal of Laryngology & Otology, vol. 120, no. 6, pp. 508–510, 2006.[3] G. T. Carter, J. D. England, and P. F. Chance, “Charcot-Marie-Tooth disease: electrophysiology, molecular genetics andclinical management,” IDrugs, vol. 7, no. 2, pp. 151–159, 2004.[4] N. Sambuughin, A. de Bantel, S. McWilliams, and K. Sivakumar,“Deafness and CMTdisease associated with a novel four aminoacid deletion in the PMP22 gene,” Neurology, vol. 60, no. 3,pp. 506–508, 2003.[5] E. Raglan, D. K. Prasher, E. Trinder, and P. Rudge, “Auditoryfunction in hereditary motor and sensory neuropathy2 Case Reports in Medicine(Charcot-Marie-Tooth disease),” Acta Oto-Laryngologica,vol. 103, no. 1-2, pp. 50–55, 1987.[6] F. G. Zeng, S. Oba, S. Garde, Y. Sininger, and A. Starr,“Temporal and speech processing deﬁcits in auditory neu-ropathy,” NeuroReport, vol. 10, no. 16, pp. 3429–3435, 1999.[7] M. C. Modest, M. L. Carlson, G. B. Wanna, and C. L. Driscoll,“Cochlear implantation in patients with superﬁcial siderosis:seven cases and systematic review of the literature,” Otology &Neurotology, vol. 36, no. 7, pp. 1191–1196, 2015.[8] M. L. Carlson, J. T. Breen, C. L. Driscoll et al., “Cochlearimplantation in patients with neuroﬁbromatosis type 2: vari-ables aﬀecting auditory performance,” Otology & Neurotology,vol. 33, no. 5, pp. 853–862, 2012.Case Reports in Medicine 3Stem Cells InternationalHindawiwww.hindawi.com Volume 2018Hindawiwww.hindawi.com Volume 2018MEDIATORSINFLAMMATIONofEndocrinologyInternational Journal ofHindawiwww.hindawi.com Volume 2018Hindawiwww.hindawi.com Volume 2018Disease MarkersHindawiwww.hindawi.com Volume 2018BioMed Research InternationalOncologyJournal ofHindawiwww.hindawi.com Volume 2013Hindawiwww.hindawi.com Volume 2018Oxidative Medicine and Cellular LongevityHindawiwww.hindawi.com Volume 2018PPAR ResearchHindawi Publishing Corporation http://www.hindawi.com Volume 2013www.hindawi.comThe Scientific World Journal8Immunology ResearchHindawiwww.hindawi.com Volume 2018Journal ofObesityJournal ofHindawiwww.hindawi.com Volume 2018Hindawiwww.hindawi.com Volume 2018 Computational and  Mathematical Methods in MedicineHindawiwww.hindawi.com Volume 2018Behavioural NeurologyOphthalmologyJournal ofHindawiwww.hindawi.com Volume 2018Diabetes ResearchJournal ofHindawiwww.hindawi.com Volume 2018Hindawiwww.hindawi.com Volume 2018Research and TreatmentAIDSHindawiwww.hindawi.com Volume 2018Gastroenterology Research and PracticeHindawiwww.hindawi.com Volume 2018Parkinson’s DiseaseEvidence-Based Complementary andAlternative MedicineVolume 2018Hindawiwww.hindawi.comSubmit your manuscripts atwww.hindawi.com

Cochlear Implantation in Charcot-Marie-Tooth Disease: Case Report and Review of the Literature

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Cochlear Implantation in Charcot-Marie-Tooth Disease: Case Report and Review of the Literature

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