Do Perioperative Systemic Corticosteroids Improve Cochlear Implant Hearing Preservation Outcomes?

Abstract

Cochlear implantation (CI) offers the opportunity to restore sound and auditory speech perception for patients with significant sensorineural hearing loss. Soft surgical techniques offer the opportunity to preserve natural hearing. Additionally, corticosteroids may improve hearing preservation (HP) by reducing inflammation in the cochlea perioperatively. The use of corticosteroids in HP in CI is supported by multiple animal studies involving guinea pigs. In a recent systematic review of the animal literature, Shaul et al. examined 155 guinea pigs who were treated with topical middle ear glucocorticoids, as well as 50 guinea pigs treated with systemic corticosteroids, compared to controls.1 With regard to topical treatment, the delivery of corticosteroid to the round window at least 30 minutes prior to CI resulted in decreased threshold shifts in high frequencies (4–32 kHz), which extended to lower frequencies when applied 1 day prior to CI.1 Steroid application immediately prior to insertion of the electrode array had no effect.1 Systemic glucocorticoids also resulted in reduced threshold shift in frequencies between 4 kHz and 24 kHz on the scale of 10 dB, though the timing of systemic steroid administration was unclear.1 There have also been several reports on the use of corticosteroids in human subjects undergoing CI. Sweeney et al. specifically studied the effect of oral corticosteroid administration on HP with a retrospective review of 27 patients.2 Styleted perimodiolar arrays were used for 35% and 28.6% of steroid and non-steroid group, respectively; all other patients were implanted with lateral wall arrays.2 Complete electrode array insertion was achieved in all subjects with 92.6% being inserted using round window approach.2 Twenty patients received a perioperative prednisone taper starting 3 days prior to surgery and lasting a total of 16 days (60 mg for 6 days, then taper by 10 mg every other day), while seven patients did not receive any oral steroids.2 Of note, both groups received intraoperative intravenous dexamethasone and topical dexamethasone application to the round window.2 Using a ratio of the difference of postoperative pure-tone average (PTA) and preoperative PTA to the difference of maximum PTA and preoperative PTA, Sweeney et al. calculated that a median 45.5% of acoustic hearing was preserved in the corticosteroid group compared to a median of 6.6% in the control group, P < .01.2 Using a definition of 80 dB or better at 250 Hz as HP, no patient in the control group had HP compared to 47.4% of the steroid group, P = .02.2 HP in the steroid group dropped by median 4.8% from the first postoperative audiogram to the latest postoperative audiogram at a median of 8.6 months after the surgery.2 Kuthubutheen et al. conducted a prospective randomized controlled trial of patients implanted with Med-El Flex 28 electrodes.3 The patients were randomized into a control group (11 patients), another group treated with a 6 day preoperative oral steroid course of 1 mg/kg/day of prednisolone (max 60 mg/day) (10 patients), and another group treated with 5 mg of intratympanic (IT) dexamethasone 24 hours prior to CI (nine patients).3 Using the PTA formula used by Sweeney et al. for HP, Kuthubutheen et al. found that mean percentage of hearing preserved was significantly higher in the IT steroid group (42.9% IT vs. 25.6% oral vs. 32.5% control) at 3 months postoperatively.3 However, at 12 months postoperatively, there was no significant difference (32.8% IT vs. 27.8% oral vs. 25.9% control).3 Cho et al. prospectively examined 19 patients implanted with Med-El Flex 28 and Cochlear 422 electrodes who received IV dexamethasone 24 hours and 1 hour prior to surgery with topical application of 2.5 mg of dexamethasone to the round window at the time of CI.4 These patients were then compared to 10 historical controls implanted with Flex 28 (20%) and styleted perimodiolar electrodes (80%) with similar preoperative PTA.4 At 12 months postoperatively, the steroid group had significantly reduced postoperative PTA compared to controls (108 dB steroid vs. 117.5 dB control, P = 0.027). 4 Skarżyńska et al. conducted a prospective study with nine patients receiving intravenous (IV) steroids 30 minutes prior to CI and continuing postoperatively for 3 days, five patients receiving a 12-day prednisone taper starting 3 days prior to CI with a single IV dose of dexamethasone 30 minutes prior to implantation, and 22 controls.5 In this study, only the oral steroid regimen had significantly higher HP rate compared to the controls after 6 months (P = 0.003).5 When specifically looking at different categories of HP (minimal HP [MHP]—0–25% of preop hearing; partial HP [PHP]—26–75% of preop hearing; and complete HP [CHP] 76–100%), the oral steroid group demonstrated 80% CHP, 20% PHP, and 0% MHP compared to IV steroid (22.2% CHP, 55.6% PHP, and 22.2% MHP) and control groups (13.6% CHP, 18.2% PHP, and 68.2% MHP).5 There is a need for more rigorous study into perioperative steroid administration for HP in CI given the small sample sizes, significant heterogeneity in HP assessment, audiologic follow-up, and electrode type. Nevertheless, there is evidence that steroid use may be beneficial. The Cho et al. study suggests that a combination of preoperative systemic steroids with topical round window application may provide durable improvement in HP, though the steroid group received only lateral wall electrodes, while the control group received mostly perimodiolar arrays, possibly accounting for this difference. The Kuthubutheen et al. study suggests there may be a short-term benefit for IT steroid injection 1 day prior to CI, but this effect was not present after 12 months. The Skarżyńska et al. and Sweeney et al. studies both support a perioperative regimen of oral steroids, ideally beginning prior to the surgery and continuing after the surgery, which may lead to a prolonged improvement in HP. Therefore, in patients where HP is desired, a perioperative oral steroid regimen should be considered if there are no medical contraindications. While it is possible that IT or topical steroids applied to the round window may be beneficial, there is insufficient evidence that these therapies produce a long-term benefit independent from systemic steroid application. Nevertheless, it would be reasonable to combine topical or IT steroid application with an oral steroid regimen. There is level 2b (prospective controlled trial) and level 3b evidence (case control study) supporting the use of a perioperative oral steroid regimen. There is level 3b evidence (case control study) supporting a combination of systemic and topical steroid application. There is level 2b (prospective controlled trial) evidence for a short-term benefit for IT steroid injection preoperatively, but no evidence of a long-term benefit.