Implant processor worn behind the ear…..Credit: University of Washington
On the head it looks like a slightly outsized hearing aid, on the inside – implanted in the vestibular system of the ear – the device brings a victim back into balance from a vertigo attack caused by Menier’s Disease. The disease, which affects several million people worldwide, causes loss of balance sensation in one and sometimes both ears. The suddenness of the attacks can be both dangerous and debilitating.
The development of the vestibular implant is a good example of scientific advancements building on other scientific advancements. In this case, product development for the now routine cochlear implant (for loss of hearing), provides the basic engineering model. Scientists and engineers at the University of Washington (Seattle, USA) have taken this model and adapted it with new sensory equipment, software, and processing to counteract the loss of balance. By working with an established approach and Cochlear Ltd. (Lane Cove, Australia), a company that builds cochlear implant devices, the team was able to bring their new device to trial many years ahead of starting from scratch.
The first human implant is scheduled for October 21, 2010 in a 56-year-old man, one of ten people that volunteered for the surgical trial. The implant portion of the device is nestled in a pocket created for it in the temporal bone of the ear. When an attack begins, the patient activates the system, and the implanted device produces electrical impulses from three electrodes inserted into the vestibular canals, a bony labyrinth within the ear. These impulses re-establish more or less normal balance signals to the brain.
To stave off nausea, afflicted people must lie still, typically for several hours and sometimes up to half a day while the membrane self-repairs and equilibrium is restored, said [James] Phillips, a University of Washington research associate professor and director of the UW Dizziness and Balance Center. Because the attacks come with scant warning, a Meniere’s diagnosis can cause people to change careers and curb their lifestyles.
Many patients respond to first-line treatments of medication and changes to diet and activity. When those therapies fail to reduce the rate of attacks, surgery is often an effective option but it typically is ablative (destructive) in nature. In essence, the patient sacrifices function in the affected ear to halt the vertigo – akin to a pilot who shuts down an erratic engine during flight. Forever after, the person’s balance and, often, hearing are based on one ear’s function.
With their device, Phillips and [Dr. Jay] Rubinstein aim to restore the patient’s balance during attacks while leaving natural hearing and residual balance function intact.
The surgical trial is one step in the U.S. Food and Drug Administration approval process. It can be several years before commercial versions of the device and an approved treatment procedure are available.