If you feel a ringing sound in your ears after going to a loud concert, researchers from the University of Michigan believe that the nerves that allows you to feel touch on your neck and face may have been affected by the loudness of the concert.
Scientists from the U-M Kresge Hearing Research Institute did a study demonstrating how nerve cells responsible for sensing touch increase their activity in the brain after cells designed for hearing are damaged. When these touch-sensing neurons become hyperactive, they are suspected to play a major role in the development of tinnitus, or ringing in the ears.
The study was headed by research professor at the Department of Otolaryngology of Kresge Hearing Research Institute at the U-M Medical School, Susan E. Shore, Ph.D. The tests were performed on animals; nevertheless, they indicate that available therapies such as acupuncture in Boynton Beach, targeted on the nerves in the head and neck, may give health benefits to certain individuals suffering from tinnitus.
When there is no outside source for the sound, tinnitus sufferers experience ringing or other sounds in their head or ears. This condition affects one person out of every ten and can be mild and intermittent or severe or chronic. In the US and Western Europe, there are about 13 million people seeking medical help for it. For war veterans, tinnitus is a growing problem. According to the American Tinnitus Association, since 2000, the number of veterans receiving service-related disability for tinnitus rose by 18% percent each year.
The number of baby boomers who are finding they can’t hear as well as they used to, also seems to be rising. Tinnitus usually occurs with hearing loss, but can also arise after a neck or head trauma such as dental work or whiplash.
Each individual may experience tinnitus in different ways. The condition can be a high-pitched and faint tone to screeching brakes, or cricket-like chirping, to swooshing ocean waves. For others, it is continuous and debilitating.
For some unexplained reason, there are people who find that if they press on the neck or face or clench their jaw, their tinnitus can be temporarily halted, or in certain instances, brought on. To know more about the condition and its strange association with touch sensations, Shore and her team performed a number of tests in guinea pigs. They measured the brain’s dorsal cochlear nucleus nerve activity. This is the part of the brain that processes auditory and other signals.
For people with good hearing, the first stop in the brain for sound signals coming from the ear through the auditory nerve is the dorsal cochlear nucleus. This nucleus is also a nexus wherein multitasking neurons process sensory signals from other parts of the brain.
According to Shore, who is also a Department of Molecular and Integrative Physiology at the U-M Medical School associate professor, “The study revealed that when a loss of hearing occurs, the brain’s other regions that normally dispatch signals to the cochlear nucleus receive a boosting effect”.
She added that when one removes one source of excitation, another source comes in to fill the void. The somatosensory system comes in, but in the process of doing so, may help bring about tinnitus
One of the body’s nerve networks, the somatosensory system, sends information to the brain regarding pain, skin temperatures, vibration, and touch. The trigeminal system is the system that provides sensations from the head and face. This system conveys signals to the cochlear nucleus allowing us to speak and hear in the process.
But when people experience hearing loss after a certain event, such as having a cavity filled or a tooth implanted, like overly helpful relatives in a family crisis, these neurons from the head and face, like too many phone calls, respond in such a way that the resulting neuron firings in the cochlear nucleus, create a phantom sound coming from the brain, what we know of is the din of tinnitus,.
In the study, Shore and her associates measured the patterns of activity of neurons in the brains of guinea pigs with deafened and normal hearing. To measure signals from the multisensory neurons in the dorsal cochlear nucleus and the trigeminal nerve, they utilized a 16-electrode array. Comparing the results from the two groups, they discovered marked differences in trigeminal nerve activity. The study revealed that in deafened animals, the somatosensory response is much stronger than in animals with normal hearing.
From earlier research, Shore and her team understood that after hearing damage, some neurons in the cochlear nucleus turn hyperactive, and this hyperactivity has been associated with tinnitus in animals. The study reveals only the neurons that get somatosensory input turn hyperactive and this should make the search for tinnitus treatments in some individuals more straightforward.
A lot of people suffering from a condition that causes frequent pain in the jaw (TMJ or temporomandibular joint syndrome), also tend to experience tinnitus. Shore’s study can result in a better understanding of this connection. TMJ sufferers have a somatosensory system that is inflamed and disrupted. Shore believes that in this type of situation, somatosensory neurons result in excessive neuron activity in the cochlear nucleus.