Two deaf women in the US have become the first people to undergo the risky procedure of having implants in their brainstems, New Scientist reports.
The devices are designed to restore hearing by directly stimulating nerves. Some deaf people have been given implants that sit just outside the brainstem, but these do not work very well.
Feeding auditory signals directly into the brainstem should work better, but because the brainstem carries signals from the entire body to the brain, any damage caused by an implant could be disastrous.
The procedure is far more risky than, say, placing implants in the cortex to try to restore some vision. “If you damage the cortex it’s not that big a deal. But at the brainstem level every neuron you damage could damage function,” says Bob Shannon of the House Ear Institute in Los Angeles, the surgeon who pioneered the procedure. “We took 15 years to convince ourselves that this could be done safely.”