Ear Implants linked To Meningitis

[Engtovo]

Parents warned to watch for symptoms in kids with devices

July 30 ‹ Children with cochlear implants to restore hearing have a small
but increased risk of dangerous bacterial meningitis, and parents should
watch for symptoms and make sure their youngsters are vaccinated, a
government study concludes.

The incidence of meningitis turned out to be greater than any of us had
realized ...¹

DR. NOEL COHEN

New York University ABOUT HALF of the increased risk appears to be
due to one model of implant that was taken off the market a year ago.
Nevertheless, children with other brands are still about 16 times more
likely than usual to have bacterial meningitis. The increased risk first came to surgeons¹ attention in the spring of 2002. It was quickly linked to an implant made by Advanced Bionics, one of three companies that sell the devices in the United States. Nearly 10,000 U.S. children with severe hearing loss have cochlear implants, which are inserted into the inner ear to activate nerves, allowing sound to be transmitted to the brain.

Last year, the Food and Drug Administration reported 52 cases of
meningitis after implants, including five deaths. The FDA and the Centers
for Disease Control and Prevention investigated the magnitude of the problem and reported the findings in Thursday¹s New England Journal of Medicine.
They studied 4,264 children who received cochlear implants between 1997 and 2002 and found that 26 had gotten bacterial meningitis.

Overall, they found 138 cases of meningitis caused by Streptococcus
pneumoniae, the most common germ, for every 100,000 years of life, which is 30 times the incidence among children the same age in the general
population. The researchers said they cannot be sure how much of this is caused by the implants themselves and how much from other factors, such as the ear abnormalities that underlie the children¹s deafness. Meningitis itself can cause deafness, and those who lose their hearing this way may be prone to later episodes.

A cochlear implant is a complex electronic device that can help to provide a
sense of sound to a person who is profoundly deaf or severely hard of
hearing.

An implant consists of the following basic parts:

* A microphone, which is worn as a headpiece behind the ear, that picks
up sound from the environment;

* A speech processor, which is usually worn on a belt or in a pocket,
that selects sounds picked up by the microphone and translates them into
electrical signals;

* A transmitter coil, which sends the signals across the skin to the
receiver/stimulator via an FM radio signal;

* The receiver/stimulator, which is secured to the skull, and receives
signals from the speech processor and converts them into electric impulses;

* Electrodes, which are implanted in the inner ear, that collect the
impulses from the stimulator and send them to the brain.

When hearing is functioning normally, thousands of sensory receptors, called hair cells, which line the cochlea ‹ a snail-shaped cavity in the inner ear convert sound waves into electrical impulses. These impulses are sent
along nerve fibers to the brain, where they are interpreted. A cochlear
implant bypasses damaged or non-working hair cells by transforming sounds into electrical energy and directly stimulating the auditory nerve.

Hearing aids and other assistive listening devices simply amplify sound. A
cochlear implant, on the other hand, transforms sounds into electrical
energy that is sent to the brain. Unlike most hearing aids, cochlear
implants have both internal and external components and require surgery to implant the internal processor.

About 14,000 people in the United States have cochlear implants, about half
of whom are children. Cochlear implant candidates have normal function in
the middle and outer ear but damaged hair cells in the inner ear. Adults who have lost all or most of their hearing later in life and have benefited only minimally from hearing aids may qualify for an implant. Children as young as 1 year with profound hearing loss in both ears may benefit, though the best age for implantation is still being debated. The implants along with language therapy can help some young children with profound hearing loss acquire speech and language. A cochlear implant requires about a three-hour surgical procedure that is performed under general anesthesia. Also, it requires intensive speech-language therapy to learn to interpret the sounds created by an implant. The total process costs about $30,000 and is generally covered by insurance.

The CDC¹s Jennita Reefhuis, principal author of the study, said the
results do not mean cochlear implants are too risky for the young.
³It¹s important for people to remember that cochlear implants can do
wonderful things for children,² she said. ³Those who are deaf can learn to
sing songs and to speak.²

Among the study¹s recommendations:

* Children getting cochlear implants should be sure to receive the
pneumococcal vaccine, which has been routinely administered to youngsters
since 2000.

* Parents should watch for signs of bacterial meningitis, which can include
high fever, stiff neck, nausea, sleepiness or confusion.

* Middle-ear infections in these children should be treated promptly.
After concern about the infections emerged last year, Dr. Noel Cohen
of New York University surveyed the 401 U.S. centers that implant the
devices and found several cases that had not been reported to the
manufacturers.

³The incidence of meningitis turned out to be greater than any of us
had realized, and while we don¹t really know all that went into it,² one
factor appeared to be the design of the Advanced Bionics implant, he said.
Unlike other implants, it contained a small wedge that pushed an
implanted electrode against the wall of the inner ear. How this increased
the risk is unclear, though possible factors were the size of the device,
trauma it caused to the inner ear and the presence of an additional foreign
body.