RESUMEN

Hearing loss may affect all age groups from the newborn to the elderly, impacting speech and language development in children and causing social and vocational problems for adults. Hearing loss can arise from anywhere in the auditory circuit including the external auditory canal, sound conduction mechanism, cochlea, cochlear nerve, and central auditory pathways. Rehabilitation options exist for all types of hearing loss, regardless of cause or location within the auditory system. Awareness of symptoms, signs, and rehabilitative measures aids primary care physicians in early identification and treatment of hearing loss.

Asunto(s)

Pérdida Auditiva/diagnóstico , Pruebas Auditivas , Implantes Cocleares , Pérdida Auditiva/etiología , Pérdida Auditiva/terapia , Humanos , Emisiones Otoacústicas Espontáneas , Factores de Riesgo

RESUMEN

Stereotactic neurosurgery originated from the pioneering work of Horsley and Clarke, who developed a stereotactic apparatus to study the monkey brain in 1908. Spiegel and Wycis applied this technology to the human brain in 1947, which ultimately lead to the development of multiple stereotactic neurosurgical devices during the 1950s. It was Lars Leksell of Sweden, however, who envisioned stereotactic radiosurgery. Leksell developed the gamma knife to treat intracranial lesions in a noninvasive fashion. His work stimulated worldwide interest and created the field of stereotactic radiosurgery.

Asunto(s)

Radiocirugia/historia , Radioterapia/historia , Historia del Siglo XX , Humanos , Neurocirugia/historia

RESUMEN

OBJECTIVE: To evaluate the hearing outcomes for a group of unilateral vestibular schwannoma patients treated with gamma knife radiosurgery and to determine if the cochlear radiation dose affects hearing outcome measures. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Vestibular schwannoma patients (n = 33) treated with gamma knife with complete audiometric follow-up. INTERVENTION: Gamma knife radiosurgery and audiometry. MAIN OUTCOME MEASURES: Pure-tone average (PTA), speech discrimination score (SDS), and cochlear radiation dose. RESULTS: The median audiometric follow-up was 24 months, with a range of 6 to 51 months (mean, 24.6 mo; standard deviation [SD], 13.9). Thirty-one patients received a maximum radiation dose of 26 Gy, and 2 received 24 Gy (mean, 25.9 Gy; SD, 0.48). All patients were treated to the 50% isodose line, and the prescription isodose was 13 Gy in 31 patients and 12 Gy in 2 patients (mean, 12.9 Gy; SD, 0.24). Mean pretreatment PTA and SDS were 55.86 dB and 45.70%, respectively. Mean PTA and SDS at last follow-up were 66.55 dB and 39.15%, respectively. The PTA at 6 months (p = 0.003), 12 months (p = 0.004), and last follow-up (p = 0.001) was significantly poorer than the pretreatment PTA. There was no significant difference between pretreatment and follow-up SDS at any time interval. The mean cochlear radiation dose was 5.2 Gy (range, 2.6-8.5 Gy). The median cochlear dose was 4.75 Gy. Fifteen patients received less than the median cochlear dose, and 18 received greater than or equal to the median cochlear dose. The change in PTA from baseline was significantly poorer at 12 months for those patients whose cochlea received 4.75 Gy (p = 0.02) or greater. Stepwise linear regression analysis using the variables of minimum SDS subsequent to baseline SDS versus total cochlear dose revealed a negative correlation (p = 0.012)-as total cochlear dose increased, SDS decreased. CONCLUSION: The PTA was significantly worse after gamma knife radiosurgery, with a mean follow-up of 24.6 months. Higher radiation doses to the cochlear volume negatively impacted hearing outcomes after radiosurgery for this group of vestibular schwannoma patients.

Asunto(s)

Cóclea/patología , Audición/fisiología , Neuroma Acústico/cirugía , Radiocirugia/métodos , Adulto , Anciano , Anciano de 80 o más Años , Audiometría , Cóclea/efectos de la radiación , Cóclea/cirugía , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Dosis de Radiación , Análisis de Regresión , Estudios Retrospectivos , Pruebas de Discriminación del Habla , Percepción del Habla , Factores de Tiempo , Resultado del Tratamiento

RESUMEN

OBJECTIVE: To evaluate the long-term hearing outcomes of neurofibromatosis type 2 (NF2) patients with cochlear implants. METHODS: Retrospective analysis of cochlear implant performance in NF2 patients using open- and closed-set speech perception testing. RESULTS: Patients with NF2-associated bilateral vestibular schwannomas frequently become profoundly deaf. The aim of surgical resection should be to preserve serviceable hearing in at least one ear; however, this goal can be difficult to achieve. Frequently, tumor size or poor preoperative hearing status can require a surgical approach that leaves the patient with a profound, bilateral sensorineural hearing loss. If the cochlear nerve is preserved anatomically after vestibular schwannoma surgery, and if promontory stimulation confirms the functionality of the cochlear nerve, then cochlear implantation is an excellent option to restore hearing. We present six cochlear implant patients with NF2 who attained a significant improvement in open- and closed-set speech understanding with a mean follow-up of 7.9 (range: 5-13) years after surgery. In all but one case, the hearing results did not deteriorate over the follow-up period. CONCLUSION: Early surgical intervention for vestibular schwannomas in NF2 patients when the cochlear nerve can be spared is an important consideration to allow for possible cochlear implantation. A 6- to 8-week recovery period for the anatomically intact cochlear nerve may be necessary to obtain a positive promontory stimulation response following tumor resection and should be performed prior to cochlear implantation.

Asunto(s)

Implantación Coclear , Pérdida Auditiva Sensorineural/etiología , Pérdida Auditiva Sensorineural/cirugía , Neurofibromatosis 2/complicaciones , Neuroma Acústico/etiología , Adolescente , Adulto , Nervio Coclear/cirugía , Femenino , Estudios de Seguimiento , Pérdida Auditiva Sensorineural/diagnóstico , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Factores de Tiempo

RESUMEN

We performed a retrospective review of 44 patients with middle ear injury incurred through the external auditory canal. Twenty-two of the 44 patients had presented to our center within 1 month of their injury (early group), and 22 presented later (delayed group); the mean interval from the time of the trauma to presentation was 6 days in the early group and 7 years in the delayed group. The causes of injury were penetrating trauma (70% of cases), thermal insults (20%), and explosive and nonexplosive blasts (9%). Purulent otorrhea, cholesteatoma, and ossicular discontinuity were more common in the delayed group. Otologic surgery was required in 9 early-group patients (41%) and in all 22 delayed-group patients (100%). Two patients in the early group developed a dead ear. The mean pure-tone averages (PTAs) at presentation were 30.7 and 52.2 dB in the early and delayed groups, respectively; after management, the corresponding mean PTAs were 21.0 and 42.5 dB. The respective mean air-bone gaps in the two groups were 14.6 and 28.2 dB at presentation and 8.0 and 17.2 dB after management. We conclude that middle ear injury incurred as a result of trauma sustained through the external auditory canal is associated with considerable morbidity. Patients who present in a delayed fashion have significantly poorer hearing at presentation and after management. Patients who do not develop a dead ear generally derive benefit from reconstruction of the middle ear sound-conduction mechanism.

Asunto(s)

Traumatismos por Explosión , Quemaduras , Conducto Auditivo Externo , Oído Medio/lesiones , Heridas Penetrantes , Pruebas de Impedancia Acústica , Adulto , Audiometría de Tonos Puros , Traumatismos por Explosión/complicaciones , Traumatismos por Explosión/diagnóstico , Traumatismos por Explosión/terapia , Quemaduras/complicaciones , Quemaduras/diagnóstico , Quemaduras/terapia , Colesteatoma del Oído Medio/etiología , Traumatismos del Nervio Facial/etiología , Femenino , Pérdida Auditiva Conductiva/etiología , Humanos , Masculino , Estudios Retrospectivos , Factores de Tiempo , Resultado del Tratamiento , Perforación de la Membrana Timpánica/etiología , Vértigo , Heridas Penetrantes/complicaciones , Heridas Penetrantes/diagnóstico , Heridas Penetrantes/terapia

Asunto(s)

Trombosis de las Arterias Carótidas/diagnóstico , Disección de la Arteria Carótida Interna/diagnóstico , Angiografía por Resonancia Magnética , Imagen por Resonancia Magnética , Arteria Carótida Interna/patología , Humanos , Aumento de la Imagen , Procesamiento de Imagen Asistido por Computador

RESUMEN

BACKGROUND: Vestibular schwannomas are known to harbor mutations in the neurofibromatosis type 2 tumor suppressor gene, but the mechanism of the neurofibromatosis type 2 tumor suppressor gene action is not well understood. Identification of genes differentially expressed in normal and diseased tissues through the use of a large-scale, cDNA microarray approach may lead to increased understanding of pathways that lead to tumor formation. OBJECTIVE: The objectives of this study were to evaluate the gene expression profiles in vestibular schwannomas in comparison with normal vestibular nerve tissues and to identify pathways that may be altered in schwannomas. METHODS: Total RNA was extracted from one normal vestibular nerve and seven vestibular schwannomas. The normal vestibular nerve was from one of the seven patients with small vestibular schwannomas. Radiolabeled cDNA was synthesized and hybridized to cDNA microarray filters that contained 25,920 known genes or expressed sequence tags. Expression profiles were imaged and analyzed. Selected genes that showed three-fold or greater difference in the intensity between the normal nerve and the schwannomas were further examined by real-time polymerase chain reaction and by immunohistochemical staining. RESULTS: Forty-two genes (0.2%) were upregulated 3-fold or more in at least 5 of the 7 tumors when the filter images were compared with a normal adjacent vestibular nerve. Among them, osteonectin, an angiogenesis mediator, and RhoB GTPase, which is important in cell signaling, were significantly upregulated in 5 of 7 tumors. Among genes that were downregulated, an apoptosis-related LUCA-15 gene was highly underexpressed in 6 of 7 schwannomas when compared with the normal nerve. Also, ezrin, a relative of the NF2 protein, was significantly downregulated in 5 of 7 tumors. Real-time PCR and immunohistochemistry data support the cDNA microarray findings. CONCLUSION: Our cDNA microarray analysis of schwannomas suggested several interesting and potentially important tumorigenesis pathways associated with vestibular schwannoma formation. Further in vivo study is necessary to define the roles of these identified genes and their potential relationships with the neurofibromatosis type 2 tumor suppressor gene.

Asunto(s)

ADN Complementario/genética , Neuroma Acústico/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Mutación Puntual/genética , Adulto , Anciano , Análisis Mutacional de ADN , Regulación hacia Abajo/genética , Femenino , Perfilación de la Expresión Génica , Genes de la Neurofibromatosis 2 , Genes Supresores de Tumor , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Neurofibromatosis 2/genética , Neurofibromatosis 2/metabolismo , Neuroma Acústico/metabolismo , Neuroma Acústico/patología , Reacción en Cadena de la Polimerasa , ARN Mensajero/genética , Nervio Vestibular/metabolismo , Nervio Vestibular/patología

RESUMEN

OBJECTIVES: The purpose of the study was to identify genes of the retinoblastoma protein (pRb)-cyclin-dependent kinase (CDK) pathway that are deregulated in vestibular schwannomas when compared with normal vestibular nerve tissues. STUDY DESIGN: Expression profiles in eight vestibular schwannomas (four sporadic tumors, one neurofibromatosis type 2 tumor, and three cystic tumors) and a paired normal vestibular nerve from one of the eight patients were chosen. Genes examined included the retinoblastoma susceptibility gene (Rb-1); cyclins D1, D2, A, and E; the CDK inhibitors p18, p19, and p27; CDK2 and CDK6; transcription factors E2F-4, E2F-5, and DP-1; and the neurofibromatosis type 2 gene. METHODS: Total RNA samples were extracted from normal vestibular nerve and vestibular schwannoma tissues and used to generate radiolabeled complementary DNA (cDNA) samples. Labeled cDNA probes were then hybridized to cDNA microarray filters. The hybridization signal was captured and quantified. Differential gene expression profiles between the normal vestibular nerve and vestibular schwannoma were compared. Real-time polymerase chain reaction and immunohistochemistry were used to further confirm the cDNA microarray data. RESULTS: Among genes in the pRb-CDK pathway, CDK2 was substantially underexpressed in seven of the eight vestibular schwannoma tumors examined. Quantitative RNA expression analysis using real-time polymerase chain reaction also showed consistent downregulation of CDK2 in the tumors. Anti-CDK2 antibody stained predominantly in the vestibular nerve and ganglion cells but only weakly in the vestibular schwannoma tissues. CONCLUSIONS: The pRb-CDK pathway was altered in all vestibular schwannoma tumors examined, with CDK2 significantly downregulated in seven of the eight tumors. Further investigation into the regulatory mechanisms governing CDK2 expression may lead to a better understanding of vestibular schwannoma tumorigenesis.

Asunto(s)

Quinasas Ciclina-Dependientes/genética , Expresión Génica , Neurofibromatosis 2/genética , Neuroma Acústico/genética , Adulto , Anciano , Análisis Mutacional de ADN , Regulación hacia Abajo , Femenino , Humanos , Técnicas para Inmunoenzimas , Masculino , Persona de Mediana Edad , Mutación , Reacción en Cadena de la Polimerasa , Proteína de Retinoblastoma/genética , Transducción de Señal