A ringing in the ears that won't go away and is increasingly distracting to many who suffer this as they age, is one of the most intractable and mysterious problems of medical science. Primary "treatments" of tinnitus have not moved much beyond simple devices to mask this annoyance.

Butnow Northstar Neuroscience (Seattle) has reported promising study results at this past weekend's annual meeting of the American Neurotology Society (The Villages, Florida) in San Diego for its cortical stimulation device in the treatment of a small group of patients with severe tinnitus in its SAHALE study.

The study's principal investigators, Brian Kopell, MD, of the Department of Neurosurgery of the Medical College of Wisconsin (Milwaukee), and David Friedland, MD, PhD, of the Department of Otolaryngology of the Medical College of Wisconsin, found that investigational cortical stimulation of the auditory cortex for the suppression of tinnitus is feasible and appears to be safe. Friedland presented the findings at the conference.

"I think we're encouraged by the results," Northstar Neuroscience COO John Bowers told Medical Device Daily. "This is the first time that electrical stimulation has been used in the U.S. to attempt to treat severe tinnitus sufferers."

He described tinnitus as the "perception of sound when there is no sound, or external sounds." Typically, Bowers said, it is caused by "some type of damage to auditory nerves that results in the auditory cortex misinterpreting signals and creating this perception of sound."

The goal of the SAHALE study was to determine if the company's implanted cortical stimulation device could alleviate at least some of the symptoms of tinnitus in a group of "pretty severe" sufferers of the condition.

Bowers also said that there are a variety of "sounds" that sufferers perceive beyond what many people commonly think of as "ringing in the ears," such as whooshing or buzzing, among others.

In the U.S., Bowers noted, 50 million people have "some type of tinnitus." About 2 million people, he said, citing data from the American Tinnitus Association (Portland, Oregon), have a severe form of the condition which can "impact their day-to-day life."

"Their ability to hold a job, their ability to socialize with other people, their ability to sleep is a real issue," he said. "And for right now, in the most severe cases, there really are no therapies and no approved therapies."

The SAHALE study, which completed patient enrollment in November, included eight patients with severe tinnitus, the average duration of which was 16 years. On a scale of zero to 100, the average severity rating came in at 79.

All patients were implanted with Northstar's investigational Renova-TT Cortical Stimulation System designed to deliver low levels of electric stimulation to the outer layer of the brain just over the auditory cortex.

The device has been described as a sort of pacemaker for the brain. It involves a small electric pulse generator implanted near the collarbone. Wiring leads from that generator, traveling under the skin of the neck into the area of the brain where a small stimulator is placed on its outer layer, the dura.

Patients initially received active or sham stimulation (crossover design) and were regularly asked to rate the loudness and severity of their tinnitus as well as the perceived effectiveness of the cortical stimulation therapy; after the crossover phase, whereby patients switched to the opposite of what they received initially, all patients received active stimulation.

Patients' quality of life also was assessed periodically using the Tinnitus Reaction Questionnaire, Tinnitus Handicap Questionnaire and the Beck Depression Inventory (BDI), since many sufferers of this condition, not surprisingly; also have to battle severe depression.

Based on the BDI, seven out of the eight patients in the study showed a decrease in BDI — that is, an improvement. Bowers described this result as "really positive and important."

Additionally, he said: "Most of the patients at some point had complete alleviation of the symptoms of tinnitus. At some point, there were periods where they had total suppression, where they had never reported that before."

No surgical complications or significant changes in hearing threshold were observed.

Northstar is planning additional work to better determine the patient characteristics that can lead to the best outcome to answer the question, "How do we make sure we get sustained positive results?"

"In this initial feasibility study, we have established that cortical stimulation appears to be safe and affect tinnitus symptoms on a long-term basis," said Kopell, one of the two investigators. "Ongoing investigation may allow us to further improve patient selection and efficacy of the therapy."

At least part of the additional clinical work will be based on further data collection with the existing patient group — "some additional evaluation and testing to better characterize the patients and the type of tinnitus and then compare that to the type of stimulation they receive — and use those as predictive factors."

Northstar's Renova system is currently under investigation for several other indications, including stroke motor recovery, aphasia and depression. The company reported encouraging results from the CHESTNUT study of aphasia in October (Medical Device Daily, Oct. 2, 2006).

Bowers told MDD that the company's EVEREST study of Renova is investigating the use of the device to restore function to hand and arm movement in stroke victims, the first indication for which Northstar is seeking a PMA from the FDA. The company expects to complete randomization in the next several weeks in EVEREST, with expectation for submission to the FDA before the end of the year. If all goes as planned, the product is expected to be ready for launch at the end of 2008 or early 2009.

The company reported in January that it had received a U.S. patent on the cortical stimulation device.

In May of 2006 Northstar in its IPO raised somewhat more than $100 million (MDD, May 8, 2006).