RESUMEN
Sustained local delivery of drugs to the inner ear may be required for future regenerative and protective strategies. The round window is surgically accessible and a promising delivery route. To be viable, a delivery system should not cause hearing loss. This study determined the effect on hearing of placing a drug-delivery microcatheter on to the round window, and delivering either artificial perilymph (AP) or brain-derived neurotrophic factor (BDNF) via this catheter with a mini-osmotic pump. Auditory brainstem responses (ABRs) were monitored for 4 months after surgery, while the AP or BDNF was administered for the first month. The presence of the microcatheter - whether dry or when delivering AP or BDNF for 4 weeks - was associated with an increase in ABR thresholds of up to 15 dB, 16 weeks after implantation. This threshold shift was, in part, delayed by the delivery of BDNF. We conclude that the chronic presence of a microcatheter in the round window niche causes hearing loss, and that this is exacerbated by delivery of AP, and ameliorated temporarily by delivery of BDNF.
Asunto(s)
Factor Neurotrófico Derivado del Encéfalo/administración & dosificación , Cateterismo/instrumentación , Catéteres de Permanencia , Catéteres Venosos Centrales , Sistemas de Liberación de Medicamentos/instrumentación , Pérdida Auditiva/tratamiento farmacológico , Audición/efectos de los fármacos , Ventana Redonda/efectos de los fármacos , Estimulación Acústica , Animales , Audiometría de Tonos Puros , Fatiga Auditiva/efectos de los fármacos , Modelos Animales de Enfermedad , Potenciales Evocados Auditivos del Tronco Encefálico/efectos de los fármacos , Cobayas , Pérdida Auditiva/diagnóstico por imagen , Pérdida Auditiva/etiología , Pérdida Auditiva/fisiopatología , Bombas de Infusión Implantables , Microscopía Confocal , Perilinfa/química , Recuperación de la Función , Ventana Redonda/diagnóstico por imagen , Ventana Redonda/fisiopatología , Factores de Tiempo , Tomografía de Coherencia ÓpticaRESUMEN
OBJECTIVE: Although adenotonsillectomy is the accepted treatment for obstructive sleep apnea (OSA) in the pediatric population, tonsillectomy has not been widely adopted in adults, and its success in this group has not been well reported. Despite the lack of current evidence, there may be an important role for tonsillectomy in selected adult cases, and further study is required. This is a pilot study from a larger group of subjects currently enrolled and awaiting surgery and repeat polysomnography. STUDY DESIGN: Retrospective series with chart review. SETTING: Tertiary referral teaching hospitals. SUBJECTS AND METHODS: Thirteen consecutive eligible subjects with tonsillar hypertrophy and OSA were identified after treatment. These patients had undergone pre- and postoperative polysomnography for assessment of the severity of sleep-disordered breathing. Post hoc analysis of key parameters was performed by Wilcoxon signed rank and paired t tests. Tonsillectomy was performed on all subjects, using the diathermy dissection technique. Nasal surgery was performed simultaneously in 11 subjects for symptomatic nasal blockage unresponsive to medical treatment. RESULTS: There was a statistically significant improvement in the severity of OSA after surgery. The total Respiratory Disturbance Index (RDI) was significantly decreased from median values of 31.7 to 5.5 (P = .0002). The RDI in rapid eye movement and non-rapid eye movement sleep and the arousal index were also significantly decreased. CONCLUSION: In selected adult subjects, tonsillectomy with intercurrent nasal surgery should be considered an effective treatment for OSA and may reduce the requirement for continuous positive airway pressure, oral appliances, or further therapeutic intervention.
