Cochlear inventor: study confirmed my research

Cochlear implant inventor Prof Graeme Clark said today that a US study released this week on the risk of meningitis in children receiving cochlear implants confirmed his findings from many years of research.

"It's a thorough study establishing what we basically knew. It's consistent with all of our research findings in the 1970s and 80s relating to risk," Clark said.

"The result, instead of being worrying, has been really positive. It has showed what clinical judgement said was happening."

Clark said that during the development of the cochlear implant, he performed extensive and meticulous animal studies to ensure that the device was as safe as it could possibly be.

"It was the one thing [Cochlear] did that set us apart from virtually everyone else," he said. "I said I wouldn't operate on patients until we had done all we could that was reasonable."

The US study, by researchers led by Jennita Reefhuis of the National Centre on Birth Defects and Development Disabilities and published in the New England Journal of Medicine, indicated that there were three factors involved in the increased risk of meningitis, Clark said.

First of all, the positioner used in the device manufactured by US company Advanced Bionics was implicated in infections, particularly sporadic or delayed infections. The company has since withdrawn the device containing a positioner. Cochlear's single component implants, originally designed by Clark, have never used a positioner.

Secondly, there was a greater risk of meningitis in the month after implant surgery, while the device was being 'sealed' into place. But Clark said that techniques had been developed by the Bionic Ear Institute in Melbourne to use the patient's own tissue in a graft that sped up the process.

Children with congenital abnormalities of the inner ear were also at greater risk of meningitis infections, but Clark noted that the study did not determine whether infections were as a result of the abnormality alone or the implant in a patient with congenital abnormalities. He said that the single death due to meningitis recorded in a patient implanted with Cochlear's device was infected via the non-implanted ear.

"If you remove perioperative infections and congenital abnormalities, then the risk of meningitis is the same as if you don't have an implant," Clark said.

Clark also said that while the study recommended vaccination of children prior to implant of a cochlear device, it did not adequately address the importance of surgical issues, such as the use of antibiotics after implant to prevent infection during the critical phase.

"In a properly organised clinic with good selection and management procedures, the risks are extremely minimal," he said.