Audiological correlates of cone beam computed tomography (CBCT) in cochlear implant recipients

Abstract

Objectives: To evaluate the role of Cone beam CT (CBCT) regarding the intracochlear electrode position, the exact localization of the electrode in either the Scala tympani or Scala vestibuli and any accompanying inner ear trauma to the delicate intracochlear structures and furthermore correlate these findings with the hearing thresholds and speech tests in patients with unilateral cochlear implant (CI).Method: A total number of 20 subjects were examined in this study, 6 males and 14 females, their ages ranged from 3 to 10 years who underwent cochlear implantation. CBCT was done to the entire study group 3 months after surgery. After one year, audio logical evaluation was done in the form of aided warble tone response, aided speech reception threshold and early speech perception test (ESP) both in quiet and in noise. The study group was subdivided according to the degree of inner ear trauma into four groups: grade 0 trauma (9 subjects), grade I trauma (3 subjects), grade II trauma (3 subjects), grade III trauma (5 subjects).Results: There was a significant difference among no trauma patients and trauma patients regarding the insertion angle, aided threshold at 250 Hz, percentage of working electrodes and ESP in noise test. Moreover, significant inverse correlation was present between the grade of trauma and both ESP in noise and the percentage of working electrodes.Conclusions: The optimal image quality and the small radiation dose renders CBCT as an optimal and secure imaging tool for the assessment of the CI electrode location and evaluation of inner ear trauma as it affects postoperative programing and hearing perspectives.