Otolaryngology’s ever-advancing frontier was on display at the Triological Society Combined Sections Meeting in a session on new developments in pediatric otology, hearing loss in adults, Eustachian tube treatment, and nerve monitoring during bilateral thyroidectomy.
Drug Delivery with Nanogel
Daniel Choo, MD, director of pediatric otolaryngology-head and neck surgery at Cincinnati Children’s Hospital Medical Center in Ohio, said using nanogel could be a better way to deliver therapies to the inner ear. In cases of childhood hearing loss caused by a cytomegalovirus (CMV) infection, prompt antiviral treatment can stabilize hearing or improve it, but more than 60% of children taking ganciclovir have to stop taking it or cut back on the dose because of Grade 3 or 4 neutropenia.
Standard application to the inner ear gives a quick peak in activity and doesn’t give the sustained response that’s needed, Dr. Choo said.
But a nanogel, which starts as a liquid at room temperature and gelatinizes at body temperature, can be used for a slower, more regular drug delivery. “Over that time,” Dr. Choo said of four-month results, “you get a much more sustained drug delivery, and it obviates this problem.” Since CMV-related hearing loss is also associated with an inflammatory response, nanogel has been developed to deliver a combination of both an antiviral and dexamethasone. Safe delivery was shown in guinea pigs in a study published last year. (Int J Pediatr Otorhinolaryngol. 2016;84:132-6.)
Favorable results using nanogel have also been seen in Meniere’s disease, and Dr. Choo said it could potentially be used to help preserve hearing in cochlear implant recipients, for hearing protection in troops, and for other purposes.
Bruce Gantz, MD, professor of otolaryngology-head and neck surgery and neurosurgery at the University of Iowa Carver College of Medicine in Iowa City, said evidence is mounting that there is a benefit to taking advantage of preserved hearing in combination with cochlear implantation.
“Functional hearing can be maintained in most of our patients if we’re careful and we use the right electrodes,” he said. For patients who don’t yet have profound hearing loss at the low frequencies—those who still have hearing better than the 85-90-decibel level at 125-500 Hz—the results are favorable, Dr. Gantz said.
In clinical trials, those who have profound hearing loss at high frequencies but acceptable preserved hearing at low frequencies, who also have an implant and use hearing aids, have word recognition rates of between 80% and 83%, Dr. Gantz said. For the best results, it’s important that patients use “all modalities,” he said.
The advantages to using acoustic hearing and electricity assistance together are better localization of sounds, better hearing of music, and greater understanding of words in noise, he said.
When testing patients for cochlear implantation, it’s critical to test in noise, Dr. Gantz said. “If you don’t do that, you’re going to have a lot of unhappy patients,” he said. “They’re crying because they cannot go out to dinner. They can’t socialize in their church, and they’re withdrawing.”
Dr. Gantz said that shorter electrodes, to preserve residual hearing at lower frequencies, tend to be used at his center. Patients with better than 80-decibel hearing at 1500 Hz are typically suitable for a shorter electrode, he said.
“We think that those who have more residual hearing do better in the long term,” he said. “They’ve got a better percentage of keeping that low frequency over time. And we know we can keep it up to 16 years now…. We need to consider implanting people younger when they do have this neural substrate, rather than older.”
Balloon Dilation for Eustachian Tube Dysfunction
Dennis Poe, MD, PhD, associate in otolaryngology and associate professor of otology and laryngology at Harvard Medical School and Boston Children’s Hospital, talked about the benefits of balloon dilation for treatment of Eustachian tube dilatory dysfunction, a procedure that just won FDA approval in September 2016 for individuals who are at least 22 years old.
Indications are persistent otitis media with effusion or non-adherent atelectasis; negative pressure on tympanogram; and inflammatory disease seen on pathology in the Eustachian tube. An exception is a patient with dysfunction that is only caused by pressure changes in a plane or while scuba diving, which must be accompanied by Eustachian tube pathology, Dr. Poe said.
The balloon is inflated, stopping before the isthmus of the Eustachian tube, and is left in for two minutes, then deflated. Researchers found that the procedure reduced inflammation in the tube. Biopsies taken immediately before the balloon dilation showed inflamed mucosa, a “disorderly” array of the pseudo-stratified columnar epithelium, loss of cilia, and submucosal inflammatory infiltrates with lymphoid follicles, Dr. Poe said.
But right afterward, the balloon has stripped off the epithelium, leaving a basal layer and “crushing” the lymphocytic infiltrate, he said. “It’s a much more impressive excoriation than you would expect from what you see clinically,” Dr. Poe said. A few weeks later, biopsies showed no lymphoid follicles, reduction in the lymphocytic infiltrate, and restoration of the pseudo-stratified columnar epithelium, with return of the ciliated border.
The result, he said, is similar to what is seen with an adenoidectomy. “We’ve realized this is a technology we’ve stumbled on that’s performing an adenoidectomy inside the lumen of the Eustachian tube,” he said. “It’s just another extension of what we all do.”
The results of a 22-center randomized trial—more details from which will be published soon, he said—showed a tympanogram normalization rate of 52% in the balloon-plus-steroid group, compared to 14% in a steroid-only group. For inclusion, patients needed to have evidence of more than 90 days of persistent or continuous Eustachian tube dysfunction, along with failed treatment with a nasal steroid spray or a week of oral steroids. The study was stopped early because of the striking disparity between the groups.
No complications were seen in the study, but anterolateral wall lacerations and false passage are those that have been most commonly seen in other studies, he said.
Vagal Nerve Monitoring during Thyroidectomy
Greg Randolph, MD, the Claire and John Bertucci Endowed Chair in Thyroid Surgical Oncology at Harvard University and director of the Massachusetts Eye and Ear Infirmary General Thyroid and Parathyroid Endocrine Surgical Division, talked about the merits of continuous vagal nerve monitoring during bilateral thyroidectomy procedures.
Vocal cord paralysis after thyroid surgery represents a significant problem, Dr. Randolph said. A systematic review from several years ago found recurrent laryngeal nerve paralysis after 9.8% of thyroidectomies.
Electromyography (EMG) testing after the procedure on the first side can avoid the mistake of moving on to the second side despite injury, a move that could lead to an airway emergency if there is bilateral nerve injury.
Intraoperative, continuous assessment through vagal nerve monitoring could prevent injury, Dr. Randolph said. Research has found that the combination of a slower nerve response and decreased amplitude, or a reduced number of fibers participating in a response, is a clear sign that a nerve is becoming injured.
Work by Dr. Randolph and others has found an EMG threshold that seems to work to identify an impending threat of nerve injury but at which damage can often be avoided when corrective action is taken (Gland Surg. 2016;5:607-616). Approximately 72% of the time, when irregular EMG activity was seen intraoperatively, the activity returned to normal once the surgical procedure associated with the EMG activity was adjusted in response, Dr. Randolph said. In cases where the EMG activity dropped to silence, though, the reversibility rate was just 17%, he said.
Tests on cost versus efficacy have found that it makes sense to do the monitoring, Dr. Randolph said. “Our work has shown that the use of nerve monitoring is cost effective for all cases of bilateral thyroidectomy by allowing the identification of first-side injury and staging surgery,” he said, “as opposed to not using monitoring, continuing the surgery, and potentially having bilateral vocal cord paralysis and tracheotomy.”
Thomas Collins is a freelance medical writer based in Florida.