A UConn Health physician-scientist has developed the first-ever blood tests for hearing loss and vertigo, and is currently testing their promise.
Dr. Kourosh Parham, associate professor and director of research in the Division of Otolaryngology — Head and Neck Surgery in the Department of Surgery at UConn Health, has discovered that two recently identified unique inner ear proteins can be detected in minute quantities in the blood, and that their levels correlate with inner ear disorders. This means that these proteins could serve as blood biomarkers, which may help improve the early detection and diagnosis of hearing loss or vertigo.
Accelerating Vertigo Diagnoses
Parham’s investigations first led him to discover a unique blood biomarker for benign paroxysmal positional vertigo (BPPV), a common condition that can cause severe dizziness due to inner ear abnormalities.
Vertigo symptoms can include sudden onset of extreme dizziness that can become nauseating and cause loss of balance, often leading to falls and bone fractures. It can have a debilitating impact on a person’s daily function and quality of life, with episodes lasting from two weeks to as long as six months.
Early identification of at-risk people will allow for intervention before disabling hearing loss or tinnitus develops, and will hopefully reduce other health complications and financial burdens linked to these conditions.
While it can strike at any age, BPPV is by far the most common cause of vertigo in the elderly. It’s challenging for primary care and emergency medicine specialists to diagnose, often leading to costly, unnecessary imaging tests.
The inner ear has crystals, called otoconia, that act as gravity detectors to help the human body balance. Normally, they don’t move. But as people age, the crystals loosen, allowing them to enter the inner ear’s sensitive canals. Loose ear crystals, jostled by a simple head turn or movement, are the culprit behind BPPV.
The inner ear secretes a number of unique proteins including Otolin-1, which is one of the building blocks of the crystals. In his 2014 study findings, published in Otolaryngology—Head and Neck Surgery, Parham reported that these crystals eventually dissolve and their derivatives are released into the body’s blood stream, where they can be detected. His study showed Otolin-1 was present in the blood of all study subjects, but at much higher levels in the blood of the BPPV population.
Currently, there are no medications to treat vertigo, only medications to suppress symptoms. According to Parham, improved tools to diagnose BPPV quickly can be followed by maneuvers to guide loose crystals back into place and relieve the dizziness sooner.
Early Hearing Loss Identification, Early Intervention
Further, Parham has demonstrated that changes in the levels of a protein called prestin in the blood are linked to hearing loss, before the loss can measured by hearing tests.
Hearing loss can be inherited, but is most often acquired through acoustic trauma, prolonged exposure to loud noise, or toxicity from medications including chemotherapy, which lead to damage of intricate cellular components of the inner ear.
Acquired hearing loss is widespread. Nearly 50 million Americans live with some type of hearing loss or tinnitus (ringing in the ears) that not only impacts their daily lives, but also has been shown to put them at higher risk of experiencing poor health outcomes and makes them twice as likely to develop dementia.
Currently, hearing loss can only be diagnosed through hearing tests such as audiograms. There is no way to detect hearing loss at its earliest stages, leaving patients vulnerable and their doctors frustrated with limited prevention and intervention options.
“Detecting early warning signs of hearing loss is critical to ease the burden and disability from this condition and to better manage the future overall health of those affected,” Parham says.
In the inner ear, a small, snail-shaped structure called the cochlea helps the body process sound. The cochlea has a series of small fluid-filled canals containing outer hair cells (OHC) that manage the cochlea’s ability to tune sound and increase its sensitivity to sound.
OHC are known to show the first damage from excessive noise or toxicity injury. Parham’s new blood test traces the specific protein — prestin — that is located in the OHC’s inner cellular membranes and released when the OHC are injured. The simple blood test detects inner ear damage and also helps quantify the extent of the hearing loss by measuring the level of the protein in the blood.
Parham’s blood tests have already proven successful in the laboratory, and he plans to conduct human clinical trials soon. He has filed a patent for the biomarker blood tests he developed.
“Our research into these biomarkers and blood tests aims to establish new clinical norms when detecting early hearing loss, vertigo, and other inner ear disorders,” says Parham. “Early identification of at-risk people will allow for intervention before disabling hearing loss or tinnitus develops, and will hopefully reduce other health complications and financial burdens linked to these conditions.”
One recent large epidemiological study estimates that as many as 35% of adults aged 40 years or older in the United States — approximately 69 million Americans — have experienced some form of vestibular dysfunction (disorders of the vestibular system, which includes parts of the inner ear and brain that control balance and eye movement). Archives of Internal Medicine,May 25, 2009