Electronic Theses and Dissertations

Identifier

6059

Date

2017

Date of Award

11-18-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Comm Sciences and Disorders

Concentration

Hearing Sciences & Disorders

Committee Chair

Lisa Lucks Mendel

Committee Member

Shaum P. Bhagat

Committee Member

Gavin M. Bidelman

Committee Member

Vikki Nolan

Abstract

Patients treated with cranial radiation therapy (RT) are at risk for developing sensorineural hearing loss (SNHL). The two manuscripts included in the dissertation prospectively reported auditory outcomes in pediatric patients treated with cranial RT for a brain tumor. The first paper examined the incidence of SNHL in children treated with photon-RT, including the onset and progression of SNHL. The study found that SNHL was prevalent in 14% of patients with a median time from RT initiation to SNHL onset of 3.6 years. Among 29 patients with follow-up evaluations after onset, 65.5% experienced progressive SNHL in either ear and 34.5% had no change. Younger age at RT initiation [hazard ratio (HR): 2.32; 95% confidence interval (CI): 1.21, 4.46], higher cochlear radiation dose (HR: 1.07; CI: 1.03, 1.11), and cerebrospinal shunting (HR: 2.02; CI: 1.07, 3.78) were associated with SNHL. The second paper assessed auditory outcomes in patients treated with proton radiotherapy (PRT) for craniopharyngioma, including the incidence, onset, and severity of SNHL. Additionally, changes in hearing and cochlear function were described by comparing distortion-product otoacoustic emission (DPOAE) levels, pure-tone audiometric thresholds for the conventional frequency (CF: 0.25 through 8.0 kHz) and extended high-frequency (EHF: 9.0 through 16 kHz) ranges, and speech-in-noise (SIN) perception scores from baseline to last evaluation. The study revealed that zero of 74 evaluable patients had clinically relevant SNHL in the CF range with no decline in SIN perception scores (P = 0.65).; 2.7% of the patients had mild SNHL in the EHF range. A decrease in hearing was observed in 32.4% of patients in either or both the CF and EHF ranges with a median time to onset of 24.6 months. DPOAE amplitude decreased at a much faster rate at higher versus lower frequencies. Overall, SNHL is a late effect of photon-RT that likely worsens over time. Conversely, clinical SNHL in children treated with PRT for craniopharyngioma was minimal and was observed in the EHF range only, suggesting that PRT may reduce the risk for significant SNHL when compared to photon-RT. However, subtle decreases in auditory function were observed, warranting long-term audiological follow-up post-RT.

Comments

Data is provided by the student.

Library Comment

dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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