Advancing Cochlear Implant Programming: X-ray Guided Anatomy-Based Fitting

BACKGROUND

Anatomy-based fitting (ABF) is a new research area in the field of cochlear implants (CIs). Despite the reported benefits and acceptable levels of ABF among CI recipients, some limitations remain, like the postoperative computed tomography (CT) scan, which is preferred for confirming electrode array insertion.

OBJECTIVE

This study aimed to investigate the feasibility of using plain film radiography (X-ray) for postoperative electrode detection and for building ABF as an alternative to CT.

METHODS

A total of 53 ears with CI were studied. All cases had routine post-insertion X-rays in the cochlear view and additionally underwent postoperative CT. The insertion angles and center frequencies measured by two independent observers were compared for each imaging modality. The angular insertion depth and center frequencies resulting from the X-ray and CT scans were then compared.

RESULTS

No significant differences were observed between the X-ray- and CT-measured angles for the electrode contacts. Radiographic measurements between the two readers showed an almost perfect (≥0.8) or substantial (0.71) intraclass correlation coefficient along the electrode contacts. X-ray images showed a mean difference of 4.7 degrees from CT. The mean semitone deviation of the central frequency between the CT and X-ray images was 0.6.

CONCLUSIONS

X-ray imaging provides a valid and easy-to-perform alternative to CT imaging, with less radiation exposure and lower costs. The radiographs showed excellent concordance with the CT-measured angular insertion depth and consequently with the central frequency for most electrode contacts. Therefore, plain X-ray could be a viable alternative in building ABF for the CI recipients.

Eustachian Tube Dysfunction Improvement Secondary to Moderate Weight Loss: Case Report

The Eustachian tube (ET) is an osteocartilaginous canal that connects the middle ear to the nasopharynx. It is one of the critical structures essential for middle ear functions. ET dysfunction causes discomfort in the affected ear and decreased hearing. This is the first case report of improving hearing and middle ear aeration and ET function secondary to body weight reduction. A 27-year-old male patient presented to the otology clinic complaining of decreased hearing for two years. Initial ear examination revealed retraction of TM on the left ear with two retraction pockets, and on the right ear, the TM was dull with one retraction pocket. The patient reported losing some of his body weight during those six months. Ear examination revealed improvement in the TM retraction in both ears. The improvement in hearing was evidenced by a serial audiogram, while the middle ear aeration was evidenced by clinical examination.

Superior semicircular canal dehiscence syndrome as assessed by oVEMP and temporal bone computed tomography imaging

To evaluate the role of oVEMP and multidetector CT scan in patients with superior canal dehiscence syndrome. Prospective study was conducted on nine patients with superior canal dehiscence syndrome (5 females, 4 males) age ranged 19-49 with mean age of 32.7 ± 9.3 years, complaining of intolerance to loud sounds and/or oscillopsia. The mean duration of illness was 18.7 ± 6.9 months, nine normal individuals as control (age and gender matched) were also included in the study. All of them underwent oVEMP and MDCT scan. Patients were of bilateral normal hearing sensitivity with no conductive impairment. All of the studied subjects (patients and controls) had identifiable contralateral oVEMP responses. MDCT scan showed dehiscence in all the patients. The dehiscence was unilateral (n = 7) and bilateral [n = 2 the other ear had a defect of 2 mm and thus was excluded from the study for fear or false diagnosis of Superior semicircular canal dehiscence syndrome (SCDS)]. Unlike the normal subject (nI = 0.94 µV ± 0.03 and pI = -0.42 µV ± 0.09), with stimulation of the affected side in SCDS, there were augmented amplitude responses (nI = 2.64 µV ± 0.35 and pI = -3.10 µV ± 0.44) in the eye contralateral to the stimulus "contralateral to the lesion". Mean oVEMP threshold for SCDS ears were 82.5 ± 7.55 dBnHL compared to 100 ± 5.77 dBnHL of the control ears. We concluded that combination of physiological and anatomical information from oVEMP and MDCT increased accuracy for diagnosis of dehiscence of superior semicircular canal.

Transient evoked otoacoustic emissions in superior canal dehiscence syndrome

Superior semicircular canal dehiscence syndrome (SCDS) is a clinical disorder that is characterized by vertigo and oscillopsia induced by loud sounds. Transient evoked otoacoustic emissions (TEOAEs) allow to noninvasively check the integrity of the cochlea. The present study aimed at identifying cochlear stress as the result of micro alterations of the cochlear functionality due to anatomic anomaly. 11 SCDS and 10 normal individuals as control group were submitted to history taking, otological examination, basic audiologic evaluation and TEOAEs analysis using the standard wideband protocol and moving time window analysis. Although TEOAEs test results showed no statistically significant difference using the standard protocol, off-line analysis of the waveforms' "effective duration" was statistically significantly shortened (p < 0.0001) when compared to normal ears. In conclusion, dehiscence of bone overlying the superior canal has been shown to have effects on inner ear function in terms of a third mobile window theory, thus altering pressure across cochlear partition with decrease in inner ear impedance.