Researchers at The University of Washington, Seattle, have placed a modified cochlear implant into the inner ear of a 56 year old man with Meniere’s disease, a severe balance disorder, that they believe will allow him to halt debilitating dizzy spells right in their tracks.
Meniere’s disease is a balance disorder characterized by mild to intense episodes of dizziness, where in the worst cases, standing and walking become impossible and the associated nausea can be completely debilitating. The attacks are believed to be cause by tears or other insults to the membranes of the vestibular tissues.
Jay Rubinstein, MD, PhD and James Phillips, PhD, developed a device to interrupt dizzy spells based on the cochlear implant, which has been used to restore hearing in deafened patients for more than 20 years. Cochlear implants are surgically implanted into the inner ear. The wire-like portion of the implant is threaded into the cochlea (a coiled, shell-like structure) and electrically stimulates it at specific contact points in response to sounds picked up by an external processor that sits atop the outer ear. The stimulated nerves send signals to the brain which interprets them as sound. The vestibular implant is placed within the labyrinth- the part of the inner ear housing the organs involved in balance. These structures include three thin tubes called the semicircular canals. The vestibular implant is threaded into one or more of the canals and electrically stimulates points along the canal. There is an external processor that sits behind the ear, just like a cochlear implant. The patient can control the activity of the electrical stimulation remotely with a hand-held control device. By turning a dial, the patient can regulate how much stimulation is being sent to the semicircular canals and can find a “sweet spot” that helps override the dizzy attacks.
The most effective traditional therapy for severe Meniere’s is a labyrinthectomy- a destructive procedure that destroys the labyrinth- the part of the inner ear that houses the vestibular apparatus. This surgery typically results in hearing loss, and is only performed on patients whose Meniere’s is unrelenting and where hearing loss or deafness has already occurred, or cannot be aided by hearing aids. Placing the vestibular implant, while it can cause some hearing loss, is viewed as less likely to cause the profound deafness which is the norm for labyrinthectomies.
The researchers implanted their vestibular implant into all three of the patient’s semicircular canals in October 2010. After allowing the patient to heal from the surgery, and the physicians had time to program the device, it was a waiting game for the patient to have a dizzy spell so that the device could be tested. After six months, they had their chance. The patient had a dizzy attack. He used the remote control to activate the stimulation and found a setting which significantly reduced the symptoms of the attack.
The researchers hope to implant nine more patients in the near future who have been cleared as candidates for the device.