Predictive Factors for Subjective Vertigo Following Cochlear Implantation: A Regional Multicenter Cohort Study of 395 Patients.

INTRODUCTION: Cochlear implantation (CI) is generally accepted as having a low rate of postoperative complications, but between 9.3% and 13% of cases experience vertigo postoperatively. This study aimed to examine patient, surgical, and device factors contributing toward the risk of postoperative vertigo. METHODOLOGY: A retrospective review was conducted of adult patients who underwent cochlear implant in a regional area of New South Wales from 2007 to 2018. A total of 395 cochlear implant cases were included in the final study. RESULTS: The overall incidence of vertigo at 3 months of follow-up was 7.1% (n = 28/395). No difference was identified in this study between rates of postoperative vertigo between device factors, including implant make (Cochlear vs. Med-El), electrode shape (perimodiolar vs. straight), and electrode model. No significant difference was found also for surgical factors such as the number of electrode rings inserted, side of implantation, or surgical approach of tympanic ramp (round window insertion vs. cochleostomy).A higher percentage of patients with preoperative vertigo experienced vertigo postoperatively (18.4%, n = 7/38), compared with the population without preoperative vertigo (6.0%, n = 21/352) ( p = 0.005). Patients with previous mastoid surgery also reported a higher rate of postoperative vertigo (20%, n = 9/45) compared with those who had not had mastoid surgery (5.43%, n = 19/350) ( p = 0.006). The mean age of patients experiencing postoperative vertigo was higher than the population without postoperative symptoms (67 vs. 63). CONCLUSION: This study of a large multicenter population outlines that patient factors are more critical than surgical or device factors when considering risk factors for vertigo post-cochlear implant.

Microsurgical access for cell injection into the mammalian cochlea.

The potential use of stem cells to repair hearing loss requires surgical access to the cochlea. Here we describe a microsurgical technique for cell injection into the mouse cochlea. Green fluorescent cells (ZsGreen-MCF10A cells) were successfully injected via a lateral wall cochleostomy into the scala media, scala tympani and scala vestibuli compartments of the cochlea. The effect of surgery on auditory function was investigated with auditory brainstem responses (ABR) to click and tone stimuli. A computerised signal-to-noise ratio detection method was developed to measure ABR thresholds in conjunction with visual inspection. Signal-to-noise ratio detection showed ABR thresholds in control mice were similar for click (33+/-7 dB) and tone stimuli (33+/-6 dB), in agreement with visual inspection (click 39+/-7 dB, tone 35+/-6 dB). The mean ABR threshold for combined click and tone stimuli was 15-45 dB greater after surgery with minimum hearing loss achieved with a small sized cochleostomy (< or =0.4mm) and by sibling matching to control mice (control 33+/-4 dB, surgery 48+/-3 dB). The microsurgical technique will provide a basis for future studies on the use of stem cells in the treatment of hearing loss.

Neck dissection of level IIb: is it really necessary?

OBJECTIVES: To determine whether resection of level IIb is necessary in elective or therapeutic neck dissections. STUDY DESIGN: Prospective case series. METHODS: Level IIb nodes were analyzed for micrometastases as separate specimens in 160 neck dissections on 148 patients with squamous cell carcinoma of the head and neck. RESULTS: In 106 elective neck dissections (N0 necks) from upper aerodigestive tract (UADT) and skin/parotid squamous carcinoma primaries, level IIb was involved in 4.5% and 33%, respectively. In 54 therapeutic neck dissections (N+ necks) from UADT and skin/parotid squamous carcinoma primaries, level IIb was involved in 25% and 71%, respectively. Apart from skin/parotid squamous carcinoma primaries, level IIb was never involved unless level IIa was also involved. CONCLUSIONS: Level IIb nodes can be left in situ in UADT primary carcinomas in nontonsillar N0 necks without significantly compromising regional clearance of micrometastases.