Is there a change in P300 evoked potential after 6 months in cochlear implant users?

Abstract Objective: There are few studies on long-latency auditory evoked potential (P300) in people with hearing loss who use a cochlear implant. Central auditory system evaluation with behavioral and electrophysiological tests is believed to help understand the neuroplasticity mechanisms involved in auditory functioning after cochlear implant surgery. This study investigated the electrophysiological processing of cortical level acoustic signals in a group of 21 adult individuals with postlingual bilateral severe-to-profound hearing loss who were submitted to cochlear implant surgery. Methods: Data were collected in three phases: pre-cochlear implant surgery, at cochlear implant activation, and 6 months after surgery. P300 measures were also registered during all phases. Tone-burst and speech stimuli were used to elicit P300 and were presented in free field. Results: Mean P3 component latency with tone-burst and speech stimuli were 352.9 and 321.9 ms in the pre-cochlear implant phase, 364.9 and 368.7 ms in the activation phase, 336.2 and 343.6 ms 6 months after the surgery. The P3 component mean latency values using tone-burst at activation were significantly different from those 6 months after cochlear implant. They were also significantly different using speech, between pre-cochlear implant and activation phases. Lower P3 component latency occurred 6 months after cochlear implant activation with tone-burst and pre-cochlear implant with speech stimulus. There was a weak correlation between mean P3 component latency with speech stimulus and time of hearing loss. There was no difference in amplitude between phases or in the comparison with the other variables. Conclusion: There were changes in P3 component latency during the period assessed, for both speech and pure-tone stimuli, with increased latency in the activation phase and similar lower results in the two other phases, Pre-CI and 6 months after CI use. Mean amplitude measures did not vary in the three phases.

Surgical and audiological results of bone-anchored hearing aids: comparison of two surgical techniques / Resultados cirúrgicos e audiológicos de próteses ancoradas no osso: comparação de duas técnicas cirúrgicas

Abstract Introduction: The bone-anchored hearing system has become the most viable treatment option for subjects with conductive or mixed hearing loss, who are unable to benefit from conventional hearing aids or middle ear surgery. Objective: To compare the surgical and audiological outcomes between the minimally-invasive Ponto surgery and a linear incision with soft tissue preservation techniques in bone-anchored hearing system recipients. Methods: A retrospective study was carried out from January 2017 to June 2018. Forty-two adult patients eligible for unilateral bone-anchored hearing system surgery with the Ponto system were included in the study. The implant and abutment lengths used varied from 3 to 4 mm and from 6 to 14 mm, according to the bone and skin thickness of the participants, respectively. Results: Twenty-two surgeries were performed using the minimally invasive Ponto surgery technique (52.4%) and 20 (47.6%) using the linear incision. The mean age of the subjects implanted with minimally invasive Ponto surgery and linear incision techniques were 42.0 and 33.3 years old, respectively. Ten male (45,5%) and 14 (70%) female patients were implanted using minimally invasive Ponto surgery and the linear incision techniques, respectively. There were no differences between pure tone audiometric thresholds and monosyllabic word recognition scores of the subjects, when comparing both surgical techniques. The minimally invasive Ponto surgery technique significantly reduced the surgical time compared to the linear incision technique. There were no differences between both surgical techniques for skin-related complications; (Holgers 3 and 4) which occurred in 18.8% for MIPS and in 25% for linear incision. Subjects included in the minimally invasive Ponto surgery technique group showed a superior cosmetic outcome, with no surgical scar or additional sutures. Conclusion: The surgical and audiological outcomes were satisfactory and were not correlated to the surgical technique selected in all subjects. When compared to the linear incision, the minimally invasive Ponto surgery technique showed reduced surgical time and superior esthetic outcomes in the postoperative follow-up.

Resumo Introdução: As próteses auditivas ancoradas ao osso têm se tornado a opção de tratamento mais viável para indivíduos com perda auditiva condutiva ou mista, incapazes de se beneficiar de aparelhos auditivos convencionais ou cirurgia da orelha média. Objetivo: Comparar os resultados cirúrgicos e audiológicos entre as técnicas minimally invasive Ponto surgery e incisão linear com preservação de tecidos moles em usuários de próteses auditivas ancoradas ao osso. Método: Foi feito um estudo retrospectivo de janeiro de 2017 a junho de 2018. Foram incluídos no estudo 42 pacientes adultos candidatos para cirurgia de prótese auditiva ancorada ao osso unilateral com o sistema Ponto. Os comprimentos de implante e pilar usados variaram de 3-4 milímetros e de 6-14 milímetros, de acordo com a espessura óssea e subcutânea dos participantes, respectivamente. Resultados: Foram feitas 22 cirurgias com uso da técnica minimally invasive Ponto surgery (52,4%) e 20 (47,6%) com incisão linear. A idade média dos indivíduos implantados com técnicas minimally invasive Ponto surgery e incisão linear foi de 42 e 33,3 anos, respectivamente. Dez homens (45,5%) e 14 (70%) mulheres foram implantadas com técnicas minimally invasive Ponto surgery e incisão linear, respectivamente. Não houve diferenças entre os limiares audiométricos em campo livre e as pontuações de reconhecimento de palavras monossilábicas dos sujeitos, quando comparadas as duas técnicas cirúrgicas. A técnica minimally invasive Ponto surgery reduziu significantemente o tempo cirúrgico em comparação com a técnica de incisão linear. Não houve diferenças entre as duas tecnicas cirúrgicas para complicações cutâneas maiores (Holgers 3 e 4), que ocorreram em 18,18% para MIPS e em 25% para incisão linear. Os indivíduos incluídos no grupo da técnica minimally invasive Ponto surgery apresentaram aspecto cosmético superior, sem cicatriz cirúrgica ou sutura adicional. Conclusão: Os resultados cirúrgicos e audiológicos foram satisfatórios e não se correlacionaram com a técnica cirúrgica empregada em todos os indivíduos. Quando comparada à incisão linear, a técnica minimally invasive Ponto surgery apresentou tempo cirúrgico reduzido e resultados estéticos superiores no seguimento pós-operatório.

Cochlear Implant in Brown-Vialetto-Van Laere Syndrome Patient.

The Brown-Vialetto-Van Laere syndrome or the riboflavin transporter deficiency syndrome is a neurodegenerative disorder initially reported by Brown in 1894, by Vialetto in 1936, and by Van Laere in 1966. The syndrome has been described in more than 100 patients since then. Hearing loss is the most common symptom of the syndrome, as most individuals have it through the development of the disease. Although there is a variation between the onset of hearing loss and the other possible symptoms, hearing loss usually begins in early childhood. Nevertheless, there are some cases describing hearing loss starting in adults. Hereby, we present a case report of a patient who started having the symptoms at the age of 14 and who had a mutation in the SLC52A3 gene, presenting with sensorineural hearing loss associated with cerebellar ataxia, who also underwent successful cochlear implant surgery.

Surgical and audiological results of bone-anchored hearing aids: comparison of two surgical techniques.

INTRODUCTION: The bone-anchored hearing system has become the most viable treatment option for subjects with conductive or mixed hearing loss, who are unable to benefit from conventional hearing aids or middle ear surgery. OBJECTIVE: To compare the surgical and audiological outcomes between the minimally-invasive Ponto surgery and a linear incision with soft tissue preservation techniques in bone-anchored hearing system recipients. METHODS: A retrospective study was carried out from January 2017 to June 2018. Forty-two adult patients eligible for unilateral bone-anchored hearing system surgery with the Ponto system were included in the study. The implant and abutment lengths used varied from 3 to 4mm and from 6 to 14mm, according to the bone and skin thickness of the participants, respectively. RESULTS: Twenty-two surgeries were performed using the minimally invasive Ponto surgery technique (52.4%) and 20 (47.6%) using the linear incision. The mean age of the subjects implanted with minimally invasive Ponto surgery and linear incision techniques were 42.0 and 33.3 years old, respectively. Ten male (45,5%) and 14 (70%) female patients were implanted using minimally invasive Ponto surgery and the linear incision techniques, respectively. There were no differences between pure tone audiometric thresholds and monosyllabic word recognition scores of the subjects, when comparing both surgical techniques. The minimally invasive Ponto surgery technique significantly reduced the surgical time compared to the linear incision technique. There were no differences between both surgical techniques for skin-related complications; (Holgers 3 and 4) which occurred in 18.8% for MIPS and in 25% for linear incision. Subjects included in the minimally invasive Ponto surgery technique group showed a superior cosmetic outcome, with no surgical scar or additional sutures. CONCLUSION: The surgical and audiological outcomes were satisfactory and were not correlated to the surgical technique selected in all subjects. When compared to the linear incision, the minimally invasive Ponto surgery technique showed reduced surgical time and superior esthetic outcomes in the postoperative follow-up.

Is there a change in P300 evoked potential after 6 months in cochlear implant users?

OBJECTIVE: There are few studies on long-latency auditory evoked potential (P300) in people with hearing loss who use a cochlear implant. Central auditory system evaluation with behavioral and electrophysiological tests is believed to help understand the neuroplasticity mechanisms involved in auditory functioning after cochlear implant surgery. This study investigated the electrophysiological processing of cortical level acoustic signals in a group of 21 adult individuals with postlingual bilateral severe-to-profound hearing loss who were submitted to cochlear implant surgery. METHODS: Data were collected in three phases: pre-cochlear implant surgery, at cochlear implant activation, and 6 months after surgery. P300 measures were also registered during all phases. Tone-burst and speech stimuli were used to elicit P300 and were presented in free field. RESULTS: Mean P3 component latency with tone-burst and speech stimuli were 352.9 and 321.9 ms in the pre-cochlear implant phase, 364.9 and 368.7 ms in the activation phase, 336.2 and 343.6 ms 6 months after the surgery. The P3 component mean latency values using tone-burst at activation were significantly different from those 6 months after cochlear implant. They were also significantly different using speech, between pre-cochlear implant and activation phases. Lower P3 component latency occurred 6 months after cochlear implant activation with tone-burst and pre-cochlear implant with speech stimulus. There was a weak correlation between mean P3 component latency with speech stimulus and time of hearing loss. There was no difference in amplitude between phases or in the comparison with the other variables. CONCLUSION: There were changes in P3 component latency during the period assessed, for both speech and pure-tone stimuli, with increased latency in the activation phase and similar lower results in the two other phases, Pre-CI and 6 months after CI use. Mean amplitude measures did not vary in the three phases.

Comprehensive evaluation of risk factors for neonatal hearing loss in a large Brazilian cohort.

OBJECTIVES: To determine the incidence and risk factors of hearing loss (HL) in Brazilian neonates. STUDY DESIGN: 11,900 neonates were screened for hearing and congenital CMV (cCMV). Low and high-risk babies who did not pass their hearing screening and infants with cCMV were scheduled for a diagnostic audiologic evaluation. RESULTS: The incidence of HL was 2 per 1000 live-born infants (95% CI: 1-3). HL was higher in high-risk neonates than in low risk babies (18.6 vs. 0.3/1000 live births, respectively). Among infants exposed to isolated risk factors, association of HL with craniofacial abnormalities/syndromes (RR = 24.47; 95% CI: 5.9-100.9) and cCMV (RR = 9.54; 95% CI: 3.3-27.7) were observed. HL was 20 to 100-fold more likely in neonates exposed to ototoxic drugs in combination with cCMV or craniofacial/congenital anomalies. CONCLUSIONS: Strategies for the prevention of cCMV and exposure to ototoxic drugs may decrease the incidence of HL in this population.

Contribution of Congenital Cytomegalovirus Infection to Permanent Hearing Loss in a Highly Seropositive Population: The Brazilian Cytomegalovirus Hearing and Maternal Secondary Infection Study.

BACKGROUND: The exact contribution of congenital cytomegalovirus infection (cCMVI) to permanent hearing loss (HL) in highly seropositive populations is unknown. We determined the contribution of cCMVI to HL and estimated the effectiveness of newborn hearing screening (HS) in identifying neonates with CMV-related HL. METHODS: A total of 11 900 neonates born from a population with ≥97% maternal seroprevalence were screened for cCMVI and HL. cCMVI was confirmed by detection of CMV-DNA in saliva and urine at age <3 weeks. RESULTS: Overall, 68 (0.6%; 95% confidence interval [CI], 0.4-0.7) neonates were identified with cCMVI. Of the 91 (0.8%) newborns who failed the HS, 24 (26.4%) were confirmed with HL, including 7 (29.2%; 95% CI, 17.2-59.3) with cCMVI. Another newborn with cCMVI passed the HS but was confirmed with HL at age 21 days. Of the 62 neonates with cCMVI who underwent a complete hearing evaluation, 8 (12.9%; 95% CI, 6.7-23.4) had HL and most (7/8; 87.5%; 95% CI, 46.6-99.7) were identified by HS. The rate of CMV-related HL was 8 per 11 887 neonates (0.7 per 1000 live births). The prevalence ratio of HL among neonates with cCMVI compared to CMV-uninfected neonates was 89.5 (95% CI, 39.7-202.0). No late-onset cCMVI-related HL was detected during a median follow-up of 36 months. CONCLUSIONS: cCMVI is an important cause of HL in childhood in all settings. Integrating targeted cCMVI screening among neonates who fail a HS could be a reasonable, cost-effective strategy to identify newborns with early-onset cCMVI-related HL.

Cochlear implant revision surgeries in children / Cirurgias revisionais de implante coclear em crianças

Abstract Introduction: The surgery during which the cochlear implant internal device is implanted is not entirely free of risks and may produce problems that will require revision surgeries. Objective: To verify the indications for cochlear implantation revision surgery for the cochlear implant internal device, its effectiveness and its correlation with certain variables related to language and hearing. Methods: A retrospective study of patients under 18 years submitted to cochlear implant surgery from 2004 to 2015 in a public hospital in Brazil. Data collected were: age at the time of implantation, gender, etiology of the hearing loss, audiological and oral language characteristics of each patient before and after cochlear implant surgery and any need for surgical revision and the reason for it. Results: Two hundred and sixty-five surgeries were performed in 236 patients. Eight patients received a bilateral cochlear implant and 10 patients required revision surgery. Thirty-two surgeries were necessary for these 10 children (1 bilateral cochlear implant), of which 21 were revision surgeries. In 2 children, cochlear implant removal was necessary, without reimplantation, one with cochlear malformation due to incomplete partition type I and another due to trauma. With respect to the cause for revision surgery, of the 8 children who were successfully reimplanted, four had cochlear calcification following meningitis, one followed trauma, one exhibited a facial nerve malformation, one experienced a failure of the cochlear implant internal device and one revision surgery was necessary because the electrode was twisted. Conclusion: The incidence of the cochlear implant revision surgery was 4.23%. The period following the revision surgeries revealed an improvement in the subject's hearing and language performance, indicating that these surgeries are valid in most cases.

Resumo Introdução: A cirurgia para a implantação do dispositivo interno do implante coclear não é inteiramente livre de riscos e pode apresentar problemas que exigem cirurgias revisionais. Objetivo: Verificar a incidência das indicações de cirurgias revisionais para a implantação do dispositivo interno do implante coclear, sua efetividade e correlacionar às variáveis relacionadas às categorias de linguagem e audição. Método: Estudo retrospectivo de pacientes menores de 18 anos submetidos à cirurgia de implante coclear de 2004 a 2015 em um hospital público no Brasil. Os dados coletados foram: idade no momento da implantação, sexo, etiologia da surdez, características audiológicas e da linguagem oral de cada paciente no pré e pós-operatório, necessidade de revisão cirúrgica e razão para ela. Resultados: Foram feitas 265 cirurgias em 236 pacientes. Oito pacientes foram submetidos ao implante coclear bilateral e 10 necessitaram de cirurgia de revisão. Foram necessárias 32 cirurgias para essas 10 crianças (um implante coclear bilateral), das quais 21 foram cirurgias de revisão. Em duas crianças, a remoção do implante coclear foi necessária, sem realização de reimplante; uma delas apresentava malformação coclear, por partição incompleta tipo I; e a outra, devido a trauma. Quanto à causa da necessidade da cirurgia revisional, das oito crianças que permaneceram com implante coclear, quatro apresentaram calcificação coclear após meningite, seguida de trauma (1), malformação do nervo facial (1), falha do dispositivo interno da IC (1) e torção do feixe de eletrodos (1). Conclusão: A incidência de cirurgias revisionais foi de 4,23%. O pós-operatório das cirurgias revisionais permite uma melhoria no desempenho de audição e na linguagem dos pacientes, indicando que essas cirurgias são válidas na maioria dos casos.

Cochlear implant revision surgeries in children.

INTRODUCTION: The surgery during which the cochlear implant internal device is implanted is not entirely free of risks and may produce problems that will require revision surgeries. OBJECTIVE: To verify the indications for cochlear implantation revision surgery for the cochlear implant internal device, its effectiveness and its correlation with certain variables related to language and hearing. METHODS: A retrospective study of patients under 18 years submitted to cochlear implant surgery from 2004 to 2015 in a public hospital in Brazil. Data collected were: age at the time of implantation, gender, etiology of the hearing loss, audiological and oral language characteristics of each patient before and after cochlear implant surgery and any need for surgical revision and the reason for it. RESULTS: Two hundred and sixty-five surgeries were performed in 236 patients. Eight patients received a bilateral cochlear implant and 10 patients required revision surgery. Thirty-two surgeries were necessary for these 10 children (1 bilateral cochlear implant), of which 21 were revision surgeries. In 2 children, cochlear implant removal was necessary, without reimplantation, one with cochlear malformation due to incomplete partition type I and another due to trauma. With respect to the cause for revision surgery, of the 8 children who were successfully reimplanted, four had cochlear calcification following meningitis, one followed trauma, one exhibited a facial nerve malformation, one experienced a failure of the cochlear implant internal device and one revision surgery was necessary because the electrode was twisted. CONCLUSION: The incidence of the cochlear implant revision surgery was 4.23%. The period following the revision surgeries revealed an improvement in the subject's hearing and language performance, indicating that these surgeries are valid in most cases.

The Relationship between Colonization by Moraxella catarrhalis and Tonsillar Hypertrophy.

We sought to investigate the prevalence of potentially pathogenic bacteria in secretions and tonsillar tissues of children with chronic adenotonsillitis hypertrophy compared to controls. Prospective case-control study comparing patients between 2 and 12 years old who underwent adenotonsillectomy due to chronic adenotonsillar hypertrophy to children without disease. We compared detection of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Pseudomonas aeruginosa, and Moraxella catarrhalis by real-time PCR in palatine tonsils, adenoids, and nasopharyngeal washes obtained from 37 children with and 14 without adenotonsillar hypertrophy. We found high frequency (>50%) of Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and Pseudomonas aeruginosa in both groups of patients. Although different sampling sites can be infected with more than one bacterium and some bacteria can be detected in different tissues in the same patient, adenoids, palatine tonsils, and nasopharyngeal washes were not uniformly infected by the same bacteria. Adenoids and palatine tonsils of patients with severe adenotonsillar hypertrophy had higher rates of bacterial coinfection. There was good correlation of detection of Moraxella catarrhalis in different sampling sites in patients with more severe tonsillar hypertrophy, suggesting that Moraxella catarrhalis may be associated with the development of more severe hypertrophy, that inflammatory conditions favor colonization by this agent. Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis are frequently detected in palatine tonsils, adenoids, and nasopharyngeal washes in children. Simultaneous detection of Moraxella catarrhalis in adenoids, palatine tonsils, and nasopharyngeal washes was correlated with more severe tonsillar hypertrophy.

Is there a best side for cochlear implants in post-lingual patients? / Existe um lado melhor para implantes cocleares em pacientes pós-linguais?

Abstract Introduction: Cochlear Implant is a sensory prosthesis capable of restoring hearing in patients with severe or profound bilateral sensorineural hearing loss. Objective: To evaluate if there is a better side to be implanted in post-lingual patients. Methods: Retrospective longitudinal study. Participants were 40 subjects, of both sex, mean age of 47 years, with post-lingual hearing loss, users of unilateral cochlear implant for more than 12 months and less than 24 months, with asymmetric auditor reserve between the ears (difference of 10 dBNA, In at least one of the frequencies with a response, between the ears), divided into two groups. Group A was composed of individuals with cochlear implant in the ear with better auditory reserve and Group B with auditory reserve lower in relation to the contralateral side. Results: There was no statistical difference for the tonal auditory threshold before and after cochlear implant. A better speech perception in pre-cochlear implant tests was present in B (20%), but the final results are similar in both groups. Conclusion: The cochlear implant in the ear with the worst auditory residue favors a bimodal hearing, which would allow the binaural summation, without compromising the improvement of the audiometric threshold and the speech perception.

Resumo Introdução: O implante coclear é uma prótese sensorial capaz de restaurar a audição em pacientes com perda auditiva neurossensorial bilateral severa ou profunda. Objetivo: Avaliar se há um melhor lado para o implante coclear em pacientes pós-linguais. Método: Estudo longitudinal retrospectivo; incluiu 40 indivíduos, de ambos os sexos, média de 47 anos, com perda auditiva pós-lingual, usuários de implante coclear unilateral por mais de 12 meses e menos de 24 meses, com perda auditiva assimétrica entre as orelhas (diferença de 10 dBNA, em pelo menos uma das frequências), divididos em dois grupos. O Grupo A foi composto por indivíduos com implante coclear na orelha com melhor audição residual e Grupo B com menor audição residual em relação ao lado contralateral. Resultados: Não houve diferença estatística entre o limiar auditivo tonal antes e depois do implante coclear. Uma melhor percepção da fala nos testes pré-implante coclear foi observada no grupo B (20%), mas os resultados finais foram semelhantes em ambos os grupos. Conclusão: O implante coclear na orelha com pior audição residual favorece uma audição bimodal, o que possibilitaria a somação binaural, sem comprometer a melhora do limiar audiométrico e a percepção da fala.

Is there a best side for cochlear implants in post-lingual patients?

INTRODUCTION: Cochlear Implant is a sensory prosthesis capable of restoring hearing in patients with severe or profound bilateral sensorineural hearing loss. OBJECTIVE: To evaluate if there is a better side to be implanted in post-lingual patients. METHODS: Retrospective longitudinal study. Participants were 40 subjects, of both sex, mean age of 47 years, with post-lingual hearing loss, users of unilateral cochlear implant for more than 12 months and less than 24 months, with asymmetric auditor reserve between the ears (difference of 10dBNA, In at least one of the frequencies with a response, between the ears), divided into two groups. Group A was composed of individuals with cochlear implant in the ear with better auditory reserve and Group B with auditory reserve lower in relation to the contralateral side. RESULTS: There was no statistical difference for the tonal auditory threshold before and after cochlear implant. A better speech perception in pre-cochlear implant tests was present in B (20%), but the final results are similar in both groups. CONCLUSION: The cochlear implant in the ear with the worst auditory residue favors a bimodal hearing, which would allow the binaural summation, without compromising the improvement of the audiometric threshold and the speech perception.

Cirurgia de reconstrução de orelha média / Middle ear reconstruction

A orelha média funciona como um amplificador sonoro. Utiliza para isso três mecanismos: o hidráulico, a alavanca dos ossículos e o jogo das janelas, sendo o mais importante o fato da energia mecânica captada pela membrana timpânica ser concentrada na área da janela oval, que é muitas vezes menor (mecanismo hidráulico). Podemos dividir o não funcionamento da cadeia ossicular em duas categorias: com diminuição da vibração da cadeia e com interrupção da cadeia. Neste artigo, o autor discorre sobre os problemas da cirurgia de reconstrução.

A new experimental model of acquired cholesteatoma.

OBJECTIVE: Cholesteatoma is a recurrent disease that is difficult control by otologists. This study aims to develop an experimental model of cholesteatoma that is easy to reproduce, using latex to induce the inflammatory reaction and propylene glycol as the foreign body in the middle ear. STUDY DESIGN: We used a new experimental model in which an intentional perforation was performed on the tympanic membrane of rats, followed by the introduction of a latex biomembrane. METHODS: A control group was submitted only to perforation of the tympanic membrane. Propylene glycol with latex was used in experimental group 1 and latex alone in experimental group 2. The rats were killed during the eighth week and their tympanic bullae were stained with hematoxylin and eosin. RESULTS: Eighty percent of the animals in group 1 and 90% in group 2 developed a cholesteatoma. No formation of cholesteatomas or inflammatory tissue occurred in the control group. CONCLUSION: The presence of inflammatory cells may provoke the production of cytokines (IL-1, IL-2, IL-6, IL-8) and growth factors, which, together with the latex biomembrane, which is known to contain a protein that favors vascular growth, may cause chemotactic migration of the squamous epithelium from the external auditory meatus to the middle year of the rat, causing a cholesteatoma. The induction of an experimental cholesteatoma in rats with latex and latex plus 50% propylene glycol was effective, representing an excellent experimental model. The theory of epithelial migration in the genesis of cholesteatomas was confirmed by our observations in rats. The latex induced an acute and chronic inflammatory reaction when in contact with the mucosa of the middle ear.