Posts tagged inner ear
The medical condition known as Ménière’s disease is characterized by severe dizziness or vertigo, a ringing which is sensed in the ears (tinnitus), and a sensation of fullness in the ear. Most commonly, this disorder affects only a single ear at a time. It can develop at any age but is far more likely to occur in adults aged between 40 and 60.
The National Institute on Deafness and Other Communication Disorders (NIDCD) estimates that somewhere around 615,000 persons in the U.S. currently are afflicted by this disorder and that each year there are approximately 46,000 new cases which develop.
Some people experience Ménière’s disease as attacks of dizziness, which either occur suddenly or following a brief period of muffled hearing. Sometimes these attacks are experienced one after another, for days at a time, and in other cases, people experience standalone attacks of dizziness, followed by episode-free periods. In some cases, attacks of Ménière’s disease can cause such extreme vertigo that the person afflicted will completely lose their balance and fall spontaneously.
What Exactly is Ménière’s Disease?
The symptoms attributable to Ménière’s disease are generally caused by an accumulation of fluid in those sections of the inner ear which comprise a structure known as the labyrinth. This labyrinth is home to the organs responsible for balance, which are the semicircular canals and the otolithic organs. The labyrinth also contains the organs responsible for hearing, known as the cochlea.
Compositionally, the labyrinth has two distinct sections, referred to as the membranous labyrinth and the bony labyrinth. The membranous portion has a fluid called endolymph, which stimulates certain receptors coincident with body movement. Those receptors then transmit signals to the brain, relative to the movement and position of the body.
In the cochlea, whenever sound vibrations are sensed, fluid compression occurs, and that triggers sensory cells to send data signals to the brain. When a person is troubled by Ménière’s disease, the endolymph accumulation in the labyrinth disrupts normal balance, as well as the signals which are transmitted between the inner ear and the brain. As a result, the affected person experiences vertigo and some of the other symptoms caused by Ménière’s disease.
Causes of Ménière’s Disease
Scientists and doctors are unsure of what the triggers are for this disorder, so there are various speculative answers which professionals ascribe to. Some believe that it is caused by blood vessel constriction similar to that which occurs during migraine headaches. Others believe that the causes of the disease are more attributable to autoimmune reactions, allergies, and viral infections. It has been noted that Ménière’s disease seems to recur in specific families, leading other scientists to believe that genetic variations may be the primary cause of the affliction.
Diagnosing Ménière’s Disease
The primary method for diagnosing Ménière’s disease is by observation of the symptoms generally associated with the disorder. Medically, these are considered to be the presence of tinnitus, a temporary hearing loss, the sensation of fullness in the ear, and at least two episodes of vertigo which persist for a period of 20 minutes or more.
A special doctor known as an otolaryngologist will generally be charged with diagnosing the condition, and since this kind of doctor is a specialist with ear, nose, and throat, he/she is best equipped to make the diagnosis. At the time of examination, a patient may be administered a hearing test to determine the extent of any hearing damage. It’s also possible that a doctor would request MRIs or CTs, to scan the entire brain.
Treatment for Ménière’s Disease
While there is no known cure for Ménière’s disease, your family doctor will probably recommend a combination of treatments which will at least help you manage the symptoms associated with the disorder. Those recommendations will generally include some of the following:
- cognitive therapy – this is a kind of talk therapy which encourages people to share their interpretation of life experiences and how they react to them. Some people benefit significantly by discussing their unexpected attacks and anxieties
- dietary changes – it appears that chocolate, caffeine, and alcohol may exacerbate symptoms experienced by someone suffering from the disorder, and by reducing intake of these, sometimes symptoms will subside
- medication – since one of the primary symptoms of the disorder is dizziness, there are some medications which can be used to manage that dizziness and shorten the duration of the attack
- lower salt intake – it can be helpful in some cases to ingest less salt and to use diuretics so that the body does not retain excess fluid, which can be a contributing factor in the ear
- surgery – when there are no other alternatives, surgery is sometimes carried out on the endolymphatic sac, so as to decompress it
- alternative medicine – scientists have not been able to determine the effectiveness of alternative types of approaches, but there are healers who insist that acupuncture or herbal supplements can have a positive impact on this disease
- injections – sometimes an injection of antibiotics into the middle ear helps to control vertigo experienced by a sufferer, but this is not commonly recommended, because it can promote hearing loss.
As adults grow older, they become more likely to develop hearing and balance disorders. Hearing loss can result from a multitude of factors, including bacterial and viral infections, environmental and work-related noise exposure, genetics, medication toxicity and trauma.
Some of these conditions affect the cochlea, which is the inner ear. As the innermost part of the vertebrate ear, this section of the body is responsible for sound detection and balance. If this part of the body is damaged, your ability to hear suffers greatly.
New research at the Indiana University School of Medicine has developed a way to grow inner ear tissue from human stem cells. The researchers’ findings may lead to better methods of treating hearing loss. Find out how they were able to achieve this success and what it means for the those with hearing impairments.
Research Into the Inner Ear
“The inner ear is only one of few organs with which biopsy is not performed and because of this, human inner ear tissues are scarce for research purposes,” said Eri Hashino, Ph.D., Ruth C. Holton Professor of Otolaryngology at IU School of Medicine. “Dish-grown human inner ear tissues offer unprecedented opportunities to develop and test new therapies for various inner ear disorders.”
In the past, researchers have had difficulties growing inner ear tissue. Traditionally, scientists cultivate human stem cells in a flat layer on a culture dish. However, this method proved unsuccessful in producing viable tissue. Research leads, Karl R. Koehler and Dr. Hashino, instead tested a different culturing technique called three-dimensional culture.
The three-dimensional culture is a technique that grows stem cells in a floating ball-shaped aggregate. This method allows the cells to grow more naturally. They incubate in an environment similar to the body. Through expert guidance, the scientists were able to create structures called “organoids.” These structures contain sensory and supporting cells akin to the ones in the inner ear.
What Does This Research Mean for the Future?
“This is essentially a recipe for how to make human inner ears from stem cells,” said Dr. Koehler, lead author of the study and whose research lab works on modeling human development. “After tweaking our recipe for about a year, we were shocked to discover that we could make multiple inner ear organoids in each pea-sized cell aggregate.”
“We also found neurons, like those that transmit signals from the ear to the brain, forming connections with sensory cells,” Dr. Koehler said. “This is an exciting feature of these organoids because both cell types are critical for proper hearing and balance.”
Dr. Hashino and his colleagues hope to use this new knowledge to study diseases and disorders that affect hearing. In addition to learning more about the ear, the scientists hope to develop new therapies and drugs.
“We hope to discover new drugs capable of helping regenerate the sound – sending hair cells in the inner ear of those who have severe hearing problems,” Dr. Hashino said. If successful, then this is another step towards healing people with hearing impairments.