Brain Imaging May Hold Clues to Ringing in the Ears
Talk about a cacophony of noises. Described as ringing in the ears, buzzing, whistling, humming, thumping, roaring and hissing, the sounds of tinnitus can range from mild to disabling.
According to the American Tinnitus Association (ATA), an estimated 50 million people in the United States and millions more around the world -- suffer from this still not fully understood disorder, including two million who are so debilitated, they cannot function normally.
Not surprisingly, tinnitus is reportedly becoming a major disability for soldiers who have suffered blast injuries in war zones. The Veterans Benefits Administration reported that at the end of fiscal year 2003, various hearing impairments, including tinnitus, were the third most common type of disability among the 2.5 million veterans receiving disability payments. At the end of 2004, annual compensation payments to veterans with tinnitus as their major disability amounted to nearly $190 million
Finding a cure for a condition that is not clear is a challenge for the medical and scientific community. Current treatment options, according to the ATA, include hearing aids, cochlear implants, relaxation techniques, some medications, as well as alternative treatments such as acupuncture, cranio-sacral therapy, and hypnosis.
Some of these techniques or a combination of several -- bring relief to some people, but effective treatment still eludes far too many sufferers.
Is It All in the Ear?
While the exact causes of tinnitus have not yet been pinpointed, it is widely believed that most cases are triggered by the damage to the microscopic endings of the inner ears hearing nerve. That is especially true in older people; in the younger ones, prolonged exposure to loud noises is thought to be the leading cause not only of tinnitus, but of hearing loss as well.
Other possible causes range from benign and treatable ones, such as wax buildup in the ear, allergies, or sinus infections, to more serious conditions, including cardiovascular disease, head or neck trauma, and certain kinds of tumors. In some cases, antibiotics, sedatives, antidepressants, anti-inflammatory drugs, or even aspirin can induce the symptoms of tinnitus.
But the ear may not be the only culprit. According to the Washington D.C.-based Society for Neuroscience, some research also indicates that tinnitus may originate not in the ear, but in the brain. Recent studies that involve brain-imaging techniques link the ailment to irregular activity in various areas of the brain, including those involved in sound processing.
Understanding the Brains Mysteries
While the desire and quest to understand the human brain goes back to Antiquity, neuroimaging non-invasive methods of seeing the brain -- is a relatively new science. The two most widely used techniques are Positron Emission Tomography (PET) and Functional Magnetic Resonance Imaging (fMRI), which are commonly used to diagnose brain tumors, strokes, and neuron-damaging diseases, such as Alzheimer's.
Multidisciplinary research teams use PET and fMRI to study various hearing-related ailments, including language acquisition, age-related hearing loss, and tinnitus.
Past and current studies using brain imaging techniques at various universities around the world focused on identifying specific sites in the brain that may be associated with tinnitus, as well as on understanding how tinnitus starts, and what areas of the brain change as tinnitus develops.
While PETs and fMRIs are the most widely used neuroimaging methods, a new technique, called Magnetic Resonance Spectroscopy (MRS) is a useful research tool as well. It can actually estimate the level of different chemicals in the brain, says Dr. Ali A. Danesh, Associate Professor of Biomedical Sciences and Director of Audiology Clinic at Florida Atlantic University. Some scientists using the MRS technique reported different amounts and concentrations of certain chemicals in the brain of people with tinnitus.
Dr.Danesh is referring to a study at the Neurosciences Institute of Albany Medical Center, New York, where scientists are using MRS to develop a database of images that shows brain activity in people who have normal hearing and no tinnitus. This database will provide a baseline for research into how the brains of people with noise-induced tinnitus differ from others.
The analysis of these images will focus on a potent brain chemical called gamma aminobutric acid (GABA), which is present in lower than normal levels in people with tinnitus. The researchers are trying to confirm a direct link between reduced GABA levels and the presence of noise-induced tinnitus. That breakthrough could simplify diagnosis of tinnitus, establish the underlying cause, and help determine the most effective treatment.
Dr. Daneshs current research focuses on recording electrical activity in the brain of tinnitus patients and comparing it to a control group, with the goal of determining what those differences are and, hopefully, shed some light on the mysteries of this condition.
More Research Is Needed
While brain imaging may eventually provide valuable clues, many answers about the causes and the treatment of tinnitus still remain unclear. A lot of work is in progress and we hope to find better ways to diagnose this condition, Dr. Danesh says. With advances in imaging and recording techniques, maybe sometime in the future we can detect where in the brain tinnitus is generated for every patient, but we are not there yet.
That would be great news and a big relief to millions of people around the world desperate for effective way to silence the distressing noises in their ears.