Physicians, nurses, aides, and medical students scuttled about, absorbed in responsibilities best described--without exaggeration--as "life or death." Oxygen tanks were rolled in place, bins of sterile gowns and drapes were wheeled into the rooms, and monitoring devices were calibrated to the smallest degree of precision. It was one of the loudest places in health care, yet a two-year-old boy lying in a hospital bed in a nondescript corner was oblivious of it all. The noise of the sterile halls eluded the child because in his mind, there was none.

    Disabilities affect more than a million Filipinos all over the archipelago, and hearing impairment comprises 13 percent of them. No national data exist identifying the causes of deafness, but general estimates rank prenatal causes as the most common. Clinical experience on the etiology of congenital deafness recognizes maternal rubella infection as its leading source.

An ear for the patient

    Lyle Dominic, the toddler at the operating room, and his twin, Liam Ethan, (scheduled for the same operation the day after) both suffer from congenital deafness. He had been wearing a hearing aid for the past 10 months. But as the critical time for language development neared and the failing sensitivity of his auditory device became more apparent, a more definite treatment acquired urgency. With the ability to communicate at stake, his parents were persuaded only the best this part of the world has to offer will suffice: premier neuro-otologist Charlotte Chiong.

    The chief of otology, neurootology, and skull-base surgery at the University of the Philippines-Philippine General Hospital (UP-PGH), Chiong is one of only two physicians in the country trained in cochlear implantation. A graduate of the UP College of Medicine, she underwent further training at Harvard University and the University of Toronto.

    Fresh from medical school, that is, after clinical internship at the UP, she had known her calling after spending time at the prestigious Baylor College of Medicine.

    "It is an interesting story," she narrated. "After I graduated, I went to the US to observe the practice of ENT…. I just wanted to know how difficult it is before entering such a program. There, I met with the assistant chairman of the department and he introduced me to cochlear implantation."

    Cochlear-implantation technology was made commercially available in 1984. Chiong was given a glimpse of the then novel technique a mere two years after, in 1986.

    "Funny thing is," she said, "that doctor (the assistant chair) told me, 'I don't know when cochlear implantation will be done in the Philippines, knowing the Philippines is a developing country…but you will be the first one there to do it'… .back then, I wasn't even an ENT resident!"

    She made up her mind then and there. "I knew exactly this is the work I wanted to do," she said. "I wanted to be able to help people, especially children born deaf, hear again."

Conductors of music and electrons

    Cochlear implants (CI) serve where conventional hearing aids can no longer provide benefit. These devices consist of multichannel electrodes directly in contact with the cochlear neurons, a receiver translating sound to electrical impulses, and an external unit containing the speech processor and battery. The CI converts sound energy to electrical energy, directly stimulating the cochlear nerve with coded electrical impulses.

    Studies by Nadol et al. showed patients with profound deafness of varying etiologies still possess spiral ganglion cells. Apparently, damage or dysfunction of cochlear hair cells account for more than 85 percent of the pathology in profound sensorineural hearing loss, and a substantial number of neurons within the cochlea remain and are amenable to hearing via CI. "Cochlear implants bypass these damaged hair cells," explained Chiong. "They directly depolarize nerve fibers proximal to the multichannel electrodes."

    The candidates for cochlear implantation are diverse and numerous. Prelingually deaf children before the age of four, individuals whose hearing loss recently became severe, and those whose hearing aids have outlived their usefulness (best aided thresholds worse than 70 dB at 250, 500 and 1000 Hertz, thresholds worse than 90 dB at 2000 Hertz, and speech-test scores worse than 50 percent) get the most benefit. Radiologic evaluation is critical for CI candidates, with temporal bone HRCT used to evaluate the cochlea and the internal auditory canal, and MRI-3DFT CISS used to confirm cochlear patency, rule out cochlear nerve aplasia and eliminate the possibility of other central-nervous-system abnormalities causing the deafness.

    MRI plates hung at OR3, where Chiong was scrubbing in for the procedure, clearly showed the anatomical details of the inner ear. "Very few people realize we are capable of imaging these structures with a high degree of resolution," she said. "There are no dyes involved in MRI-3DFT CISS, only a specialized computer program that analyzes the resonance images."

    Only one company--Medical Electronics--supplies cochlear implants in the Philippines.

Into the auditory canal

    With Lyle adequately draped and anesthetized, Chiong proceeded to shave off hair from a thin strip of the patient's temporal scalp. "You can actually do this now, just shave off the part where you will cut," she said. "Unlike before where you have to shave the entire head."

    Implant positions and incision sites were marked on the skin and through the temporalis to the temporal bone. Deftly, the neurootologist opened a skin flap and created a crevice in the bone (using the markers as guide) where she would lodge the CI receiver. "With CIs, unlike pacemakers, patients can undergo MRI without turning the magnets off--radiologists only have to change some parameters from the imaging modality," she said. "Although in airports, they will still set off the metal detectors, and will thus need to carry special cards identifying them as CI patients."

    She then approached the tympanic canal through the mastoid process, carefully from behind. Burring a limited hole through the mastoid (a "limited mastoidectomy"), she moved on to the most critical part of the surgery: the posterior tympanotomy.

    "The facial canal lies in your field during posterior tympanotomy," she explained after the procedure. "This is where the risks of the surgery are most concentrated. The advances over the years have made the implantation a very safe technique, and here you only have to take care not to damage the seventh nerve." Being the neurootology expert, she made it look effortless.

    After identifying the stapedius tendon, the footplate and the round window, she entered the cochlea through a burr hole less than 1.2-mm wide at the promontory, a structure antero-inferior to the round window.

    "The electrode is 0.6 mm with a marker that lodges into your cochleostomy," she said (pointing to the hole she just made). "The marker provided at the end of this electrode will prevent it from being pulled out. However, you can always put in temporalis fascia just to make sure."

    After placing the electrode array into the cochleostomy site, the coils were set in place. "The electrodes are designed to be redundant, to accommodate the growth of the child's skull," she added. Using fissures drilled earlier into the temporal bone on the periphery of the crevice, Chiong fixed the receiver with sutures.

    Though the procedure's difficulty was not adequately demonstrated because of the experienced hands of Chiong, she emphasized that it takes constant application of implantation techniques to make sure one remains adept and proficient. "Currently, because of financial constraints, there are only about 10 CI procedures a year. You cannot divide that number with a lot of surgeons…like parotid surgery, one needs to perform around five a year to keep up to speed," she clarified. "This is one of the reasons there remains only two cochlear- implant specialists in the country."

Echoes of affirmation

    Preparing to close the flaps and end the procedure, Chiong acknowledged the important contributions of the multidisciplinary team. "Right now, CI involves a team of specialists tasked with different aspects of the program."

    Evident even inside the operating room, the team gave the neurootologist a better chance of implanting CI's without untoward complications.

    While Chiong was maneuvering her way through the posterior tympanotomy, a neurologist at the end of the room was measuring impulses from electrodes placed at the vicinity of the facial nerve. The surgeon proceeded only if the neurologist gave the go-signal. Upon placement of the electrodes, audiologists with laptop computers and electronic probes determined the number of channels in contact with the membrane overlying the distal parts of the cochlear nerve. With nods from both specialists in the OR, she proceeded with the closing.

    "In the UP-PGH, we now have in place a very comprehensive cochlear-implantation program," she said. "We have audiologists, speech pathologists, otolaryngologists…all involved in the care of the patient with a hearing impairment."

A sound future

    With years of experience in cochlear implantation (her first involved two postlingual deaf patients back in 1998), Chiong notes that the progress is encouraging. "We were the first in Asia to undertake bilateral cochlear implantation in a single operation. We made medical history."

    She now believes a surgical training program for neurootologists is a few years away. "Right now, we are developing a program for ENTs. I think it is best that ENTs are trained for CI because they have a lot of experience in temporal bone surgery--which is an essential part of cochlear implantation."

    She also hopes more deaf patients will be given the opportunity to hear again, because of cochlear implants. "The cheapest CI is still very expensive, around $12,500. But we have had a few indigent patients receive them through corporate sponsorships and charity organizations."

    She laments the absence of government funding for these unfortunate individuals. "When you look at it from an economic perspective, it is more cost-effective to give a child a CI rather than spend the succeeding years training him/her in special schools. In other countries, CIs are covered by HMOs and insurance. Studies abroad showed it is high up in the list of cost-effective devices, even higher than cardiac pacemakers."

    She recalls: "Back when I was a medical student, patients with hearing impairments who were referred to the ENT were merely sent to hearing-aid centers. You can't do anything for the patient." Now, with the advent of CI and its exponential advances, things are very much different. "Now, there is something I can do," she says with pride--exactly what she just did to a two-year-old child.

    Lyle and Liam waited a month before their CIs were activated--to allow for their tissues to adjust to the foreign object and sufficient healing of the surgical wounds. In no time at all, like almost every single one of Chiong's patients, they will be "in the mainstream," living their lives attuned to the rhythm of the world.

 

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SOUNDING OFF

When her twins, Lyle Dominic and Liam Ethan, were scheduled to undergo cochlear implantation, Mrs. Agnes Atienza felt a bit edgy--after all, which parent wouldn't be worried when their two-year-old kids had been scheduled to undergo a long and tedious surgical procedure?

    But it goes without saying that the surgery was going to be crucial to her kids' development. At that age, kids who have no hearing difficulties are starting to hone their communication skills. For Lyle and Liam, who had been diagnosed with congenital deafness, to develop their communication skills, something had to be done soon.

    And what needed to be done went beyond fitting them with hearing aids or eventually making them learn sign language.

    Dr. Charlotte Chiong, the neurootologist who looked after--still does--Lyle and Liam, explains that for interventions to work at all, the age of the patients must be taken as an important consideration. The crucial period is between ages two and four; if the intervention were performed later, its chance of being effective could decrease.

    On the morning of March 30, 2004, Lyle was wheeled into an operating room at Capitol Medical Center. Liam underwent the procedure the following day.

    Now, nearly a year after the surgery, Mrs. Atienza is more than gratified to see the changes that are happening in her kids' lives--as well her husband's and her own. She describes these changes as "overwhelming."

    Although the kids are still trying to get themselves used to wearing the implants--especially after the implants had been switched on in April--they have been recovering excellently. Even Chiong is happy to witness the kids' progress.

    Now three years old, Lyle and Liam are as active and playful as most other kids their age. Looking back at the past year, Mrs. Atienza has this to say: "It's worth it." J. P. de Guzman

 

 

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