Hearing tests can fail to diagnose hearing loss: study

April 21, 2017

Washington, Apr 21: A team of US researchers has revealed that the traditional clinical hearing tests often fail to diagnose patients with a common form of inner ear damage, which otherwise might be detected by some behavioural tests.

HearingAccording to researchers, the reason why some forms of hearing loss may go un-recognised in the clinic is that hearing involves a complex partnership between the ear and the brain and the central auditory system can compensate for significant damage to the inner ear by turning up its volume control, partially overcoming the deficiency.

This type of "hidden hearing loss" paradoxically presents itself as essentially normal hearing in the clinic, where audiograms -- the gold-standard for measuring hearing thresholds -- are typically conducted in a quiet room.

"You can have tremendous damage to inner hair cells in the ear that transmit information to the brain and still have a normal audiogram," said lead study author Richard Salvi from University at Buffalo.

"But people with this type of damage have difficulty in hearing in certain situations, like hearing speech in a noisy room. Their thresholds appears normal," Salvi added. About 95 percent of sound input to the brain comes from the ear's inner hair cells.

"Ear damage reduces the signal that goes the brain and it results trouble in hearing, but that's not what's happening here, because the brain "has a central gain control, like a radio, the listener can turn up the volume control to better hear a distant station." Salvi stated.

The sound is converted to neural activity by the inner hair cells in the auditory part of the ear, called the cochlea.

Sound-evoked neural activity then travels from the cochlea to the auditory nerve and into the central auditory pathway of the brain. For people with inner hair cell loss, sound is less faithfully converted to neural activity in the cochlea.

It is not clear how many people might have this type of hearing loss, but Salvi noted in the journal Frontiers in Neuroscience that it is a common complaint to have difficulty hearing in noisy environments as people get older.

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Agencies
May 19,2020

Researchers have found that patients with peripheral artery disease or stroke were less likely to receive recommended treatments to prevent heart attack than those with coronary artery disease. All three are types of atherosclerotic cardiovascular disease.

Depending on the location of the blockage, atherosclerosis increases the risk for three serious conditions: coronary artery disease, stroke and peripheral artery disease.

"Our study highlights the need for public health campaigns to direct equal attention to all three major forms of atherosclerotic cardiovascular disease," said senior study author Erin Michos from the Johns Hopkins University in the US.

"We need to generate awareness among both clinicians and patients that all of these diseases should be treated with aggressive secondary preventive medications, including aspirin and statins, regardless of whether people have heart disease or not," Michos added.

Since atherosclerosis can affect arteries in more than one part of the body, medical guidelines are to treat coronary artery disease, stroke and peripheral artery disease similarly with lifestyle changes and medication, including statins to lower cholesterol levels and aspirin to prevent blood clots.

Lifestyle changes include eating a healthy diet, being physically active, quitting smoking, controlling high cholesterol, controlling high blood pressure, treating high blood sugar and losing weight.

What was unclear was if people with stroke and peripheral artery disease received the same treatments prescribed for those with coronary artery disease.

This study compared more than 14,000 US adults enrolled in the 2006-2015 Medical Expenditure Panel Survey, a national survey of patient-reported health outcomes and conditions, and health care use and expenses.

Slightly more than half of the patients were men, the average age was 65, and all had either coronary artery disease, stroke or peripheral artery disease.

These individuals were the representative of nearly 16 million US adults living with one of the three forms of atherosclerotic cardiovascular disease.

Compared to participants with coronary artery disease, participants with peripheral artery disease were twice more likely to report no statin use and three times more likely to report no aspirin use.

Additionally, people with peripheral artery disease had the highest, annual, total out-of-pocket expenditures among the three atherosclerotic conditions.

The findings showed that participants with stroke were more than twice as likely to report no statin or aspirin use.

Moreover, those with stroke were more likely to report poor patient-provider communication, poor health care satisfaction and more emergency room visits.

"Our study highlights a missed opportunity for implementing life-saving preventive medications among these high-risk individuals," Michos said.

The study was presented in the virtual conference at the American Heart Association's Quality of Care & Outcomes Research Scientific Sessions 2020.

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Agencies
July 21,2020

New Delhi, Jul 21: The Centre has written to all states and union territories warning against the use of N-95 masks with valved respirators by people, saying these do not prevent the virus from spreading out and are "detrimental" to the measures adopted for its containment.

The Director General of Health Services (DGHS) in the Ministry of Health, in a letter to the Principal Secretaries of health and medical education of states, said it has been observed that there is "inappropriate use" of N-95 masks, particularly those with valved respirators, by the public other than designated health workers.

The DGHS referred to the advisory on the use of homemade protective cover for face and mouth available on the website of the Ministry of Health.

"It is to bring to your knowledge that the use of valved respirator N-95 masks is detrimental to the measures adopted for preventing the spread of coronavirus as it does not prevent the virus from escaping out of the mask. In view of the above, I request you to instruct all concerned to follow the use of face/mouth cover and prevent inappropriate use of N-95 masks," DGHS Rajiv Garg said in the letter.

The government had in April issued an advisory on the use of homemade protective cover for face and mouth, asking people to wear it, particularly when they step out of their residences.

The advisory stressed such face covers must be washed and cleaned each day, as instructed, and stated that any used cotton cloth can be used to make this face cover.

The colour of the fabric does not matter but one must ensure that the fabric is washed well in boiling water for five minutes and dried well before making the face cover. Adding salt to this water is recommended, it said.

It also listed the procedures of making such homemade masks, asking to ensure it fits the face well and there are no gaps on the sides.

It urges people to wash hands thoroughly before wearing the face cover, switching to another fresh one as the face cover becomes damp or humid, and never reusing it after single use without cleaning it.

"Never share the face cover with anyone. Every member in a family should have separate face cover," the advisory stated.

India's COVID-19 case tally crossed the 11-lakh mark on Monday, while the total number of recovered patients increased to over seven lakh, according to Union health ministry data.

The death toll due to the disease rose to 27,497 with 681 fatalities reported in one day.

The ministry data updated at 8 am on Monday showed that a record single-day jump of 40,425 COVID-19 cases had taken the total number of cases to 11,18,043.

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International New York Times
July 7,2020

The coronavirus can stay aloft for hours in tiny droplets in stagnant air, infecting people as they inhale, mounting scientific evidence suggests.

This risk is highest in crowded indoor spaces with poor ventilation, and may help explain superspreading events reported in meatpacking plants, churches and restaurants.

It’s unclear how often the virus is spread via these tiny droplets, or aerosols, compared with larger droplets that are expelled when a sick person coughs or sneezes, or transmitted through contact with contaminated surfaces, said Linsey Marr, an aerosol expert at Virginia Tech.

Follow latest updates on the Covid-19 pandemic here

Aerosols are released even when a person without symptoms exhales, talks or sings, according to Marr and more than 200 other experts, who have outlined the evidence in an open letter to the World Health Organization.

What is clear, they said, is that people should consider minimizing time indoors with people outside their families. Schools, nursing homes and businesses should consider adding powerful new air filters and ultraviolet lights that can kill airborne viruses.

What does it mean for a virus to be airborne?

For a virus to be airborne means that it can be carried through the air in a viable form. For most pathogens, this is a yes-no scenario. HIV, too delicate to survive outside the body, is not airborne. Measles is airborne, and dangerously so: It can survive in the air for up to two hours.

For the coronavirus, the definition has been more complicated. Experts agree that the virus does not travel long distances or remain viable outdoors. But evidence suggests it can traverse the length of a room and, in one set of experimental conditions, remain viable for perhaps three hours.

How are aerosols different from droplets?

Aerosols are droplets, droplets are aerosols — they do not differ except in size. Scientists sometimes refer to droplets fewer than 5 microns in diameter as aerosols. (By comparison, a red blood cell is about 5 microns in diameter; a human hair is about 50 microns wide.)

From the start of the pandemic, the WHO and other public health organizations have focused on the virus’s ability to spread through large droplets that are expelled when a symptomatic person coughs or sneezes.

These droplets are heavy, relatively speaking, and fall quickly to the floor or onto a surface that others might touch. This is why public health agencies have recommended maintaining a distance of at least 6 feet from others, and frequent hand washing.

But some experts have said for months that infected people also are releasing aerosols when they cough and sneeze. More important, they expel aerosols even when they breathe, talk or sing, especially with some exertion.

Scientists know now that people can spread the virus even in the absence of symptoms — without coughing or sneezing — and aerosols might explain that phenomenon.

Because aerosols are smaller, they contain much less virus than droplets do. But because they are lighter, they can linger in the air for hours, especially in the absence of fresh air. In a crowded indoor space, a single infected person can release enough aerosolized virus over time to infect many people, perhaps seeding a superspreader event.

For droplets to be responsible for that kind of spread, a single person would have to be within a few feet of all the other people, or to have contaminated an object that everyone else touched. All that seems unlikely to many experts: “I have to do too many mental gymnastics to explain those other routes of transmission compared to aerosol transmission, which is much simpler,” Marr said.

Can I stop worrying about physical distancing and washing my hands?

Physical distancing is still very important. The closer you are to an infected person, the more aerosols and droplets you may be exposed to. Washing your hands often is still a good idea.

What’s new is that those two things may not be enough. “We should be placing as much emphasis on masks and ventilation as we do with hand washing,” Marr said. “As far as we can tell, this is equally important, if not more important.”

Should I begin wearing a hospital-grade mask indoors? And how long is too long to stay indoors?

Health care workers may all need to wear N95 masks, which filter out most aerosols. At the moment, they are advised to do so only when engaged in certain medical procedures that are thought to produce aerosols.

For the rest of us, cloth face masks will still greatly reduce risk, as long as most people wear them. At home, when you’re with your own family or with roommates you know to be careful, masks are still not necessary. But it is a good idea to wear them in other indoor spaces, experts said.

As for how long is safe, that is frustratingly tough to answer. A lot depends on whether the room is too crowded to allow for a safe distance from others and whether there is fresh air circulating through the room.

What does airborne transmission mean for reopening schools and colleges?

This is a matter of intense debate. Many schools are poorly ventilated and are too poorly funded to invest in new filtration systems. “There is a huge vulnerability to infection transmission via aerosols in schools,” said Don Milton, an aerosol expert at the University of Maryland.

Most children younger than 12 seem to have only mild symptoms, if any, so elementary schools may get by. “So far, we don’t have evidence that elementary schools will be a problem, but the upper grades, I think, would be more likely to be a problem,” Milton said.

College dorms and classrooms are also cause for concern.

Milton said the government should think of long-term solutions for these problems. Having public schools closed “clogs up the whole economy, and it’s a major vulnerability,” he said.

“Until we understand how this is part of our national defense, and fund it appropriately, we’re going to remain extremely vulnerable to these kinds of biological threats.”

What are some things I can do to minimize the risks?

Do as much as you can outdoors. Despite the many photos of people at beaches, even a somewhat crowded beach, especially on a breezy day, is likely to be safer than a pub or an indoor restaurant with recycled air.

But even outdoors, wear a mask if you are likely to be close to others for an extended period.

When indoors, one simple thing people can do is to “open their windows and doors whenever possible,” Marr said. You can also upgrade the filters in your home air-conditioning systems, or adjust the settings to use more outdoor air rather than recirculated air.

Public buildings and businesses may want to invest in air purifiers and ultraviolet lights that can kill the virus. Despite their reputation, elevators may not be a big risk, Milton said, compared with public bathrooms or offices with stagnant air where you may spend a long time.

If none of those things are possible, try to minimize the time you spend in an indoor space, especially without a mask. The longer you spend inside, the greater the dose of virus you might inhale.

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