In a recent paper in Science Robotics, a multi-disciplinary team of engineers and surgeons from the University of Bern in Switzerland described their experience of developing and clinically translating a surgical robot to access the cochlea for cochlear implant (CI) surgery. The drill attached to their custom-developed, multi-articulated arm robot was optically tracked, as was the patient, allowing the robot to accurately guide the drill through the facial recess to the cochlea. To date, the team has used this system on four patients, demonstrating its clinical feasibility and plans on extending the robot's capabilities to include cochleostomy and electrode array insertion.

While some have expressed safety and accuracy concerns about the trending shift from manual to robot-assisted interventions, I counter: What took us so long? In virtually every field outside of medicine, robotic automation is a no-brainer when repetitive, manual tasks require high precision, e.g., assembling cars. However, with an infinitely more expensive substrate—that is, a human patient—our current standard of care remains manual despite the known limits of human operators and suboptimal outcomes with electrode placement.

Robotics

While highly trained and talented, surgeons are human. The smallest force that humans can reliably appreciate is approximately 20 millinewtons (mN), which is about the force associated with holding a paperclip with your fingertips. During CI surgery, surgeons are supposed to “…insert [the electrode] until resistance is met,” as noted in a manufacturer's surgical manual. Considering that rupturing the basilar membrane requires a force of 30 mN, surgeons may not be able to reliably feel when intracochlear damage occurs.

The limits of human abilities may be better illustrated by the current outcomes of manual CI electrode placement. At least two groups have reported cases of tip fold-over occurring in about two percent of Cls.  At least three groups have reported that translocation of electrode arrays from scala tympani to scala vestibuli happens approximately one-third of time when using pre-curved electrodes that are threaded off stylets during insertion. Why do these incidents happen? Human operators are blindly inserting universal-sized electrodes into an organ—the cochlea—that varies in size between individuals using tools—their hands—that cannot likely sense when damage occurs. On the other hand, robots, such as that of the Bern group, have the advantage of x-ray vision for image-guided surgery, and could be programmed to perform patient-specific insertions while monitoring force and position.

Making robotic technology even more compelling is the overwhelming need for CIs—a demand that current or future manual models are unlikely to satisfy. CI manufacturers report that about 700,000 CI surgeries have been performed worldwide. The World Health Organisation, however, estimates that the global need for CI now exceeds 11 million. It is doubtful that each CI surgeon in the world can work 10 times harder to try to meet this need. Training programs tend to offset retiring physicians, and any attempt to expand the workforce would take decades. The only ways to solve this supply and demand mismatch is through technological innovations, such as robotics and simplified surgical approaches, and/or other advances that obviate the need for CIs (e.g., hair cell regrowth).

Whether the Bern robot becomes the panacea for CI surgery remains to be seen. Keep in mind that the technological marvel of CI was introduced with wide skepticism just over 40 years ago. And, while documentation of improved outcomes (e.g., more consistent final electrode location in scala tympani, better audiological outcomes, shorter operative times, etc.) will be necessary before widespread adoption of robotics for CI surgery, hearing health professionals need to remain open to the next breakthroughs providing our patients with the best treatment options.

Sept 2017  WTHR

A little boy from Kentucky had an amazing day Monday, hearing for the very first time. Connor Higgins has already been on a bit of a journey in his young life. He loves to laugh, he loves to have fun, but early on, his parents knew something wasn't right. "When we tried to talk to him, heh wouldn't have any eye contact," Hope Higgins said. Last year, Connor was diagnosed with auditory neuropathy. "Basically where his brainwaves and soundwaves do not link up," Hope said. "He's typically developing, except he can't hear," said audiologist Dr. Shelley Moats. "He's been living in a world of silence, not knowing his name, not being able to hear us say, 'I love you.' It's been really hard," Hope said. Connor has been communicating with gestures and by making noises. Hearing aids don't work.

Connor Higgins

 So in August, he had bi-lateral cochlear implant surgery. Those implants were turned on for the first time. "Knowing that he might be able to hear today is awesome," Hope said. Connor's parents were a little nervous, too. Moats walked them through how the implants work, ran a few tests, did a fitting, but once they were turned on, Hope wanted the first words her son heard to be, "Connor, mommy and daddy love you.” The toddler doesn't know words or what they mean, but he noticed loud noises. "When she made the loud sound, I seen his eyes and seen him look to see where it was coming from. That made me hopeful. I'm really excited," Hope said. Connor has a long road ahead of him. He's going to have many follow-up appointments and speech therapy. His parents' homework is to make a lot of noise. So first on their list when they got home was to watch Connor's favorite movie, "The Secret Life of Pets," turned up loud.

Hope and Jacob didn't want their son to feel different, so they got tattoos to match his cochlear implant.

Sept 2017 Huffington Post Australia

Sydney mother Anthea Hunter had no clue her four-year-old daughter Summer had any hearing issues. After all, she passed early hearing checks with flying colours and she seemed to be doing well at pre-school. But when another local mum, Carolyn Mee, was in the early stages of developing a game to help her Sound Scouts game, to detect hearing loss in children, Hunter offered then-four year old Summer to be a case study. Hunter was shocked to learn that Summer had severe hearing loss. Further tests found she was born with 'sensorineural loss'.

Hunter said there is no history of hearing loss within the family, and Summer has had no serious childhood illnesses (often a cause of hearing loss in children); so she'd never thought about getting further tests. "When Summer played Sound Scouts, I didn't think anything of it as I had no idea she had any hearing issues. Your child plays a fun game and, as the game continues, the background noise is gradually increased. But, as the noise increased, Summer could no longer hear the game's instructions, Hunter said. It was really shocking to see that she could no longer hear”

Summer HunterSound Scout"Summer's hearing loss means that if she's doing group work at school, she is only able to hear what's happening on her table, if there's not much background noise. But, once there's background noise, she cannot hear the people she is sitting closest to. So it really has a serious impact on her life."

There's no universal hearing screening program for children entering primary school, which means many are starting school with hearing loss. These kids can be inattentive, easily-distracted and find listening to instructions difficult. Many kids end up being misdiagnosed with an attention disorder, leading to needless and potentially dangerous prescription medication use. Dr Henry Cutler, from the Macquarie University Centre for the Health Economy, is in the process of evaluating Sound Scouts to determine the lifetime benefits of screening upon entering school. He said parents need to know the risks posed by childhood hearing conditions. "It's extremely important parents test their child's hearing, beyond the newborn test. Because if a child goes undiagnosed with hearing loss, it can have lifetime consequences in terms of mental health, income and employment," Dr Cutler said. "The newborn test is good for testing congenital hearing loss at birth, but some kids acquire hearing loss in the first five years of life. So it's very important for kids to be tested before entering school, so parents know they can fully engage in the classroom."

Summer is now aged eight, wearing a hearing aid and doing extremely well in the classroom, as well as the all-important playground. "Summer didn't know there was anything wrong with her hearing. For her, it was just normal that she would stop hearing if the background noise became too loud," said Anthea Hunter. Sound Scouts is now receiving funding from NSW Health and it can be downloaded via an app.

Sept 2017 Hearing Journal

Poor performance after cochlear implantation is uncommon. When it does occur, the problem is often related to the device. Overall, about five to seven percent of children and one to three percent of adults will experience device failure, which can be categorised as a hard or soft failure. Since the U.S. Food and Drug Administration (FDA) considers cochlear implants class III high-risk devices, all failed devices are returned. In fact, manufacturers need to track every device from the time it is shipped out until it is returned due to a device failure or when the patient passes away. For an explanted device, the manufacturer needs to perform an analysis, then submit a report to the FDA and the cochlear implant team that removed the device.

A hard failure occurs when the device completely fails to function. This can be an electronic malfunction resulting from a blow to the device or from a loss of hermiticity, particularly when body liquids enter the device, causing a short circuit. Hard failures can also occur when electrodes are shaved off due to the device's micro-motions. This can also happen when there is significant kinking of the electrode during the insertion process, which can eventually lead to serious electrode damage. Prior to explantation, an integrity test is performed by the manufacturer representative. If a hard failure is confirmed, explantation and re-implantation are planned.

A soft failure is when a device does not fail the manufacturer's integrity test but exhibits some problems. When a user feels that the device is not functioning as well as it used to, a thorough investigation of the implant and external components are performed by the audiology team. This includes switching the cables, using different programs on the processor, and having the patient demonstrate how to use the device. Once a technical issue has been ruled out, the device manufacturer is contacted to perform an integrity test on the device. Integrity tests include a thorough assessment of the internal receiver and stimulator and an evaluation of the stimulation rate and intra-cochlear electrodes using common ground testing. Once these processes are found to be normal, imaging is obtained to evaluate the position of the electrode. In our clinic, we prefer the use of a CT scan, which can determine the exact location of the electrode and the number of contact points inside and outside of the cochlea. Some clinics use x-rays to evaluate the electrode's position. While x-rays show if the electrode is curled in the cochlea, they do not show if some of the electrodes are outside of the cochlea. In addition, the electrode can rarely be curled in the superior semicircular canal, which can be misinterpreted as a correct placement. The primary advantage of the x-ray over the CT is the lower radiation exposure for the patient. If the imaging shows that the electrode is fully within the cochlea, a final check is done with the manufacturer representative to confirm if the device is a soft failure. After this confirmation, the revision process can begin.

In surgery, great care should be taken to protect the explanted device. If the device is damaged, detailed notes of the intra-operative damage should be made to inform the manufacturer of the damages before and during the surgery. The explanted device, along with the notes, are placed in a special container and sent to the manufacturer for testing. In our practice, most of the surgical process is generally performed under a microscope to prevent any inadvertent damage to the cochlear implant. After an initial incision, the wound is dissected slowly under the microscope until the electrode is found. In children, this process is more difficult because of the regrowth of the mastoid cortex. Sometimes the implant electrode may weave in and out of the regrown mastoid cortex in a child. The electrode and device body should be dissected gently. The device body and ground electrode (if present) are removed, and a new device body is placed in the subcutaneous pocket. The electrode is then removed from the cochlea and immediately replaced with the electrode of the new device. This process must be done quickly to make sure that new electrode is placed into the cochlea's fibrous pocket, which contained the previous electrode, before it collapses. Thus, the new electrode must be placed as soon as the explanted electrode is removed. The surgery is followed by intraoperative testing with impedance and neural response telemetry.