As for which imaging modality is best for screening children, part of that calculus involves the etiology of SSD, which is often more complex than that for children with bilateral hearing loss. Therefore, screening candidates for CI is vitally important, especially to rule out cochlear nerve deficiency (CND) or eighth nerve hypoplasia. Cochlear nerve deficiency is a contraindication for CI and is reported to occur in 46% in children with SSD (Otolaryngol Head Neck Surg. 2013;149:318-325). “We want to rule out CND before we even consider children for candidacy,” Dr. Park said.
Explore This Issue
August 2022The best way to screen patients for CND is with high-resolution 3D magnetic resonance imaging (MRI), noted Dr. Young. “It’s important to know that computer tomography will not identify a significant subset of ears with CND, nor does the presence of residual hearing exclude CND,” said Dr. Young. “I felt that, as a physician on the task force, it was a very important message that high-resolution MRI be done to avoid CND-related poor outcomes. At present there is no evidence that binaural hearing benefits will occur in this SSD population.”
For patients with meningitis, “MRI is also the most sensitive modality for identifying patency problems inside the inner ear,” Dr. Young added. “If the child’s MRI shows early signs of obstruction, that’s a reason to go ahead with CI as soon as possible,” she said.
Optimal Age: The Earlier the Better
There’s another challenge: FDA approval parameters may be too narrow. Most experts agree that the optimal age of implant should be the same as the one for bilateral congenital deafness. However, the current FDA indications for SSD specify that candidates have a maximum duration of deafness of 10 years and minimum age of 5 years.
“I tip my hat to the FDA for including children in the SSD indications developed in response to an adult clinical trial,” Dr. Young said. “However, based on 30-plus years of data and experience in implantation of children with bilateral deafness, picking 5 years of age as a minimum age is arbitrary.” For children with congenital SSD, or [those] that develop SSD early in life, “reducing the period of auditory deprivation is going to improve outcomes,” Dr. Young stressed.
Dr. Bush agreed. “The big gap within the FDA guideline is that it doesn’t address those children with congenital SSD, because if we’re implanting them at 5 years of age, many of their central neural pathways have reorganized to preclude optimal binaural hearing.”