Scientists unravel the complex brain mechanisms responsible for tinnitus

4 05 2015

Scientists have undertaken a unique study to help them unravel the complex brain mechanisms responsible for tinnitus.

Dr William Sedley, from Newcastle University’s Institute of Neuroscience

For the first time, researchers have recorded directly from the brain of someone with the condition to find the brain networks linked to causing the debilitating problem in order to gain a better understanding of the issue.

Dr William Sedley, from Newcastle University’s Institute of Neuroscience, co-led the international research with Dr Phillip Gander, from the University of Iowa in America. Their research contrasted brain activity during periods when tinnitus was relatively stronger and weaker.

The research was only possible because the 50-year-old man they studied required invasive electrode monitoring for epilepsy. He also happened to have a typical pattern of tinnitus, including ringing in both ears, in association with hearing loss.

Findings of the research, which are today (April 23) published in the Cell Press journal Current Biology, shed new light on the mechanisms of tinnitus and it is hoped that this will eventually lead to better treatments for patients.

The researchers found the expected tinnitus-linked brain activity, but they report that the unusual activity extended far beyond circumscribed auditory cortical regions to encompass almost all of the auditory cortex, along with other parts of the brain.

Dr Sedley said: “This is a big step forward in our understanding of tinnitus, as it is the first time we have been able to clearly associate the patient’s own subjective experience of tinnitus with direct and precise measurements of brain activity.

“Perhaps the most remarkable finding was that activity directly linked to tinnitus was very extensive, and spanned a large proportion of the part of the brain we measured from. In contrast, the brain responses to a sound we played that mimicked the tinnitus were localised to a tiny area.

“We hope that the extra amount of knowledge we have gained will indirectly help us to develop more treatments for patients in the future. For Newcastle University to collaborate with scientists in America reflects the great work that’s going on into this common condition.”

Approximately one in five people experience tinnitus, the perception of a sound – often described as ringing – that isn’t really there. In the UK it is estimated that around six million people have mild tinnitus, with around 600,000 experiencing it to the severity where their quality of life is affected.

The study may help to inform treatments such as neurofeedback, where patients learn to control their ‘brainwaves’, or electromagnetic brain stimulation, according to the researchers. A better understanding of the brain patterns associated with tinnitus may also help point towards new pharmacological approaches to treatment.

Dr Sedley, who also works for Newcastle Hospitals NHS Foundation Trust’s neurology department, added: “We now know that tinnitus is represented very differently in the brain to normal sounds, even ones that sound the same, and therefore these cannot necessarily be used as the basis for understanding tinnitus or targeting treatment.”

Studies on the patient took place in the University of Iowa’s Institute for Clinical and Translational Science, where patients requiring epilepsy surgery are often studied for up to two weeks with electrodes implanted in their brains, in order to locate the part of the brain responsible for the epilepsy so that it can be removed.

Dr Gander said: “It is such a rarity that a person requiring invasive electrode monitoring for epilepsy also has tinnitus that we aim to study every such person if they are willing.

“The sheer amount of the brain across which the tinnitus network is present suggests that tinnitus may not simply ‘fill in’ the ‘gap’ left by hearing damage, but also actively infiltrates beyond this into wider brain systems.”

The research was funded by the Wellcome Trust and Medical Research Council in the UK, and the National Institutes of Health in the USA. At present the research is based on a single patient, but over time the researchers are hopeful of being able to study more patients with tinnitus in a similar way.

Dr Ralph Holme, Action on Hearing Loss Head of Biomedical Research, said: “Tinnitus is a debilitating condition, for which there is currently no cure.

“We welcome investment and research into tinnitus as the mechanisms behind it are still not fully understood and more progress is needed to improve the chances of effective treatments in the future.”

 

Case study

Father-of-two Lindsay Waddell has suffered from tinnitus for 10 years and welcomes the new research.

The head gamekeeper has spent most of his life working on farms and believes the constant noise of heavy machinery has contributed towards his condition.

Mr Waddell, 64, from Middleton-in-Teesdale, County Durham, said: “My tinnitus has got worse over the years and it sounds like a constant hissing in my ears. Since I was a teenager I’ve been surrounded by the loud noise of farm machinery and I think this has damaged my hearing.

“I’m delighted that this research has been carried out as it’s a great step forward in understanding tinnitus, which will hopefully help lead to the development of new treatments in the future for those suffering the condition.

“Newcastle University is often leading the way with research and this is another example of that.”

 

 

Ncl.ac.uk [en línea] Newcastle (UK): ncl.ac.uk, 04 de mayo de 2015 [ref. 23 de abril de 2015] Disponible en Internet: http://www.ncl.ac.uk/press.office/press.release/item/scientists-unravel-the-complex-brain-mechanisms-responsible-for-tinnitus



Canceling Noise

30 06 2014

Audio games may enhance hearing in noisy environments

The ability to hear soft speech in a noisy environment is difficult for many and nearly impossible for the 48 million people in the United States living with hearing loss. Harvard Medical School researchers at Massachusetts Eye and Ear have programmed a new type of game that trained both mice and humans to enhance their ability to discriminate soft sounds in noisy backgrounds. Their findings are published in PNAS.

 

Image: iStock

Image: iStock

In the experiment, adult humans and mice with normal hearing were trained in a rudimentary “audiogame.” Inspired by sensory foraging behavior, the game required the subjects to discriminate changes in the loudness of a tone presented with a moderate level of background noise. The results suggest new therapeutic options for patients who receive little benefit from conventional sensory rehabilitation strategies.

“Like the children’s game ‘hot and cold,’ our game provided instantaneous auditory feedback that allowed our human and mouse subjects to home in on the location of a hidden target,” said senior author Daniel Polley, HMS assistant professor of otology and laryngology and director of Mass Eye and Ear’s Amelia Peabody Neural Plasticity Unit of the Eaton-Peabody Laboratories. “Over the course of training, both species learned adaptive search strategies that allowed them to more efficiently convert noisy, dynamic audio cues into actionable information for finding the target.

“To our surprise, human subjects who mastered this simple game over the course of 30 minutes of daily training for one month exhibited a generalized improvement in their ability to understand speech in noisy background conditions,” Polley said. “Comparable improvements in the processing of speech in high levels of background noise were not observed for control subjects who heard the sounds of the game but did not actually play the game.”

The researchers recorded the electrical activity of neurons in auditory regions of the mouse cerebral cortex to gain some insight into how training might have boosted the ability of the brain to separate signal from noise. They found that training substantially altered the way the brain encoded sound.
 
In trained mice, many neurons became highly sensitive to faint sounds that signaled the location of the target in the game. These neurons also displayed increased resistance to noise, retaining an ability to encode faint sounds even under conditions of elevated background noise.

Daniel Polley in the Amelia Peabody Neural Plasticity Unit of the Eaton-Peabody Laboratories. Image: Eric Antoniou/Mass Eye and Ear

Daniel Polley in the Amelia Peabody Neural Plasticity Unit of the Eaton-Peabody Laboratories. Image: Eric Antoniou/Mass Eye and Ear

“Again, changes of this ilk were not observed in control mice that watched, and listened, to their counterparts play the game. Active participation in the training was required; passive listening was not enough,” Polley said.

These findings illustrate the utility of brain-training exercises that are inspired by careful neuroscience research, he added.

“When combined with conventional assistive devices such as hearing aids or cochlear implants, audio games of the type we describe here may be able to provide the hearing impaired with an improved ability to reconnect to the auditory world,” Polley said.

“Of particular interest is the finding that brain training improved speech processing in noisy backgrounds—a listening environment where conventional hearing aids offer limited benefit,” said Jonathon Whitton, lead author on the paper. A principal investigator at the Amelia Peabody Neural Plasticity Unit, Whitton is affiliated with the Program in Speech Hearing Bioscience and Technology, Harvard–MIT Division of Health Sciences and Technology.

This work was supported by National Institutes of Health Grants R01 DC009836 and P30 DC5029 and by a grant from the Mass Eye and Ear Curing Kids Fund.

Adapted from a Mass Eye and Ear news release.

 

By MARY LEACH

 

Hms.harvard.edu [en línea] Cambridge, MA (USA): hms.harvard.edu, 30 de junio de 2014 [ref. 18 de junio de 2014] Disponible en Internet: http://hms.harvard.edu/news/canceling-noise-6-18-14



European study reveals new causes of mouth and throat cancer

21 04 2014

Poor oral health and failure to have regular dental checks could increase the risk of mouth and throat cancer, according to a pan-European study.

The research also suggests – based on a small number of tumour patients – that excessive use of mouthwash may also cause this particular form of cancer. Excessive use is defined as more than three times a day.

It has been established for some time that smoking and heavy alcohol consumption, particularly in combination, are strongly related to mouth and throat cancers. Low socio-economic status is also recognised as a contributory factor.

Now, however, a new study carried out by researchers at the University of Glasgow Dental School – as part of a Europe-wide collaboration co-ordinated by the International Agency for Research on Cancer and led by the Leibniz Institute for Prevention Research and Epidemiology – BIPS in Bremen, Germany  – has identified new risk factors for upper aerodigestive tract cancer (cancer of the mouth, larynx, pharynx and esophagus).

The study of 1,962 patients with mouth and throat cancers, with a further 1,993 people used as comparison control subjects, was conducted in 13 centres across nine countries and supported by EU funding.

Prof. Wolfgang Ahrens, Deputy Director of the BIPS, said: “These results are really important. Up until now, it was not really known if these dental risk factors were independent of the well known risks for mouth and throat cancers – smoking, alcohol and low socioeconomic status.”

The researchers were able to strip out the causation factors of smoking, alcohol and socio-economic factors, and still found there was a connection between poor oral health and increased risk of mouth and throat cancers.

The findings are highly “nuanced” and there is an interconnectedness of many of the risk factors, he stressed, but there was now evidence that poor oral health and poor dental care were also part of the picture.

The definition of poor oral health included people who had complete or part dentures, people with persistently bleeding gums.

“People should not assume that if they wear dentures and have none of their own teeth left, they have no need to see a dentist,” said Dr David Conway, Clinical Senior Lecturer at the University of Glasgow Dental School and one of the senior authors of the study. “On the contrary, even if you have got dentures, you should make sure you go for regular check-ups,” he said.

People with poor dental care were defined as those who hardly ever or never brushed their teeth or visited the dentist. The frequency of dental visits should be determined by a dentist’s risk assessment and if people fell into the low risk category it could be once a year or even every two years, said Dr Conway.

“It is not a case of ‘one size fits all’. Visits could be six-monthly, but certainly not five-yearly,” Dr. Conway added.

The possible role of mouthwash as a causative factor would require further research, said Professor Ahrens. There might be a relationship between excessive use of mouthwash and people who used it to mask the smell of smoking and alcohol. Nevertheless, the researchers found that “frequent use of mouthwashes (3-plus times per day) was associated with an elevated risk of developing mouth and throat cancer”, although they were unable to analyse the types of mouthwash used many years ago by participants in the study.

Dr Conway said: “I would not advise routine use of mouthwash, full stop. There are occasions and conditions for which a dentist could prescribe a mouthwash – it could be that a patient has a low salivary flow because of a particular condition or medicine they are taking. But for me, all that’s necessary in general is good regular brushing with a fluoride toothpaste and flossing combined with regular check-ups by a dentist.”

The research group, which includes collaborators from Germany, UK, Estonia, Switzerland, Greece, the Czech Republic, Italy, Norway, Spain, USA, Croatia, Ireland and France, have recently received a new tranche of funding from the EU and WHO’s International Agency for Research of Cancer, which will be used to research prognostic factors as well as risk factors.

 

 

Find out more:

 

Oral health, dental care and mouthwash associated with upper aerodigestive tract cancer risk in Europe: the ARCAGE (Alcohol-Related Cancers and Genetic-susceptibility in Europe) study. Wolfgang Ahrens; Hermann Pohlabeln; Ronja Foraita; Mari Nelis; Pagona Lagiou;Areti Lagiou; Christine Bouchardy; Alena Slamova; Miriam Schejbalova; Franco Merletti; Lorenzo Richiardi; Kristina Kjaerheim; Antonio Agudo; Xavier Castellsague; Tatiana Macfarlane; Gary J Macfarlane; Yuan-Chin Amy Lee; Renato Talamini; Luigi Barzan; Cristina Canova; Lorenzo Simonato; Peter Thomson; Patricia McKinney; Alex D McMahon; Ariana Znaor; Claire M Healy; Bernard E McCartan; Andres Metspalu; Manuela Marron; Mia Hashibe; David I Conway; Paul Brennan.

 

Published in Oral Oncology http://www.oraloncology.com/article/PIIS1368837514000657/abstract

 

 

Gla.ac.uk [en línea] Glasgow (UK): gla.ac.uk, 21 de abril de 2014 [ref. 04 de abril de 2014] Disponible en Internet: http://www.gla.ac.uk/news/headline_320819_en.html



Colocan por primera vez un implante auditivo de conducción ósea con anestesia local

10 12 2012

Especialistas del Departamento de Otorrinolaringología de la Clínica Universidad de Navarra han colocado por primera vez en el mundo un implante auditivo de conducción ósea con anestesia local.

Foto: EP/CUN

Foto: EP/CUN

Se trata de una intervención quirúrgica indicada para implantar un dispositivo específico para subsanar lesiones del oído externo y medio. El implante, denominado Bonebridge (nombre comercial, de la casa MED-EL), a diferencia de otros dispositivos de conducción ósea, presenta la particularidad de quedar totalmente oculto bajo la piel, sin ningún tipo de conexión percutánea que la atraviese, según ha explicado la Clínica en un comunicado.

Así, el audioprocesador externo del implante queda sujeto mediante imanes y envía la información sonora a la parte implantada en el interior, utilizando ondas de frecuencia modulada, sin precisar el empleo de una conexión directa, como ocurre en el grupo de los implantes osteointegrados.

El equipo de otorrinolaringólogos de la Clínica Universidad de Navarra ha realizado ya con éxito el procedimiento en seis pacientes, “sin ningún tipo de complicaciones quirúrgicas”.

Las cirugías han sido lideradas por el doctor Manuel Manrique, junto a quien han intervenido los doctores Raquel Manrique y Jorge de Abajo. El procedimiento tiene una duración de entre 30 y 60 minutos y, posteriormente, no precisa ingreso hospitalario.

El implante Bonebridge consta de dos componentes. El primero es un dispositivo subcutáneo (colocado bajo la piel) situado detrás de la oreja y el segundo, un procesador de audio externo encargado de captar las ondas sonoras. Estas señales se transmiten, a través de la piel, al implante interno que a su vez consigue conducirlas al hueso y, por medio de él, al oído interno del paciente.

BENEFICIOS DE LA ANESTESIA LOCAL

La importancia de la utilización de anestesia local en estas intervenciones, con el paciente totalmente consciente, estriba, en primer lugar, en una reducción de los riesgos que la anestesia general supone para el intervenido.

Además, convierte la cirugía en un procedimiento de carácter ambulatorio, sin necesidad de ingreso hospitalario, lo que contribuye a disminuir los costes del procedimiento. Finalizada la intervención, es preciso esperar tres semanas para poder activar el implante, tiempo necesario para la cicatrización de la herida quirúrgica y la remisión del edema (hinchazón).

En este procedimiento, la anestesia se infiltra en la región posterior de la oreja, emplazamiento donde quedará colocado el implante.

La realización de esta cirugía con anestesia local ha sido posible, según afirma el doctor Manrique, gracias a que el equipo de especialistas de la Clínica Universidad de Navarra cuenta con una experiencia de 20 años en cirugías del oído medio con esta modalidad anestésica. “Debido a este bagaje, sabemos que es perfectamente ejecutable este tipo de intervención con esta forma de anestesia, la cual permite realizar cirugías que requieren incluso mayor precisión que la de este tipo de implante BoneBridge“, alega el especialista.

 

 

europapress.es [en línea] Madrid (ESP): europapress.es, 10 de diciembre de 2012 [ref. 28 de noviembre de 2012] Disponible en Internet: http://www.europapress.es/navarra/noticia-colocan-primera-vez-mundo-implante-auditivo-conduccion-osea-anestesia-local-20121128111935.html