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How Can Tinnitus Retraining Therapy Facilitate Habituation to a Problematic Tinnitus

admin — Tue, 09 Apr 2019 20:51:49 +0000

How Can Tinnitus Retraining Therapy Facilitate Habituation to a Problematic Tinnitus admin Tue, 04/09/2019 - 16:51

Tinnitus is defined as the perception of sound(s) in the ears or head when no external sound is present. While it is often referred to as “ringing in the ears,” tinnitus can present as different sounds, including buzzing, hissing, whistling, swooshing, and clicking. Tinnitus is also described as a “phantom sound” or “phantom auditory sensation” that shares many similarities with chronic pain disorders.

There are two types of tinnitus: subjective and objective tinnitus.

Subjective tinnitus is generated by the brain (auditory cortex) in response to disturbances within the auditory system. Subjective tinnitus is only audible to the patient. Objective tinnitus is rare and is defined as the perception of sound(s) generated by sound sources in the body that are transmitted to the ear such as a blood vessel adjacent to the middle ear (pulsatile tinnitus). Objective tinnitus can be audible to others such as in the case of rapid muscle spasms of the soft palate (myoclonus).

Tinnitus is not considered a disease but rather a condition resulting from a wide range of health issues. Tinnitus is most commonly caused by noise exposure, age-related changes, whiplash and head injury, acoustic neuroma, side-effect of some prescription medications (e.g., high dose of aspirin, some antibiotics, antidepressants and chemotherapy agents), Ménière’s disease, otosclerosis, ear infection, severe cold and flu, Eustachian tube dysfunction and aerotitis, temporomandibular joint dysfunction, diabetes, high blood pressure, hyperthyroidism, arthritis, stress, anxiety and depression.

Tinnitus is almost always accompanied by hearing loss. It is estimated that 90% of tinnitus patients present with some degree of hearing loss. Patients with tinnitus may also experience decreased sound tolerance. The most common form of decreased sound tolerance is hyperacusis which is characterized by the experience of discomfort and sometimes ear pain with everyday sounds such as dishes clanking, babies crying, dogs barking, cars honking and sirens of emergency vehicles. It is estimated that 40% of tinnitus patients present with hyperacusis.

Tinnitus is a prevalent condition. It is estimated that 15% to 20% of the general population experiences tinnitus at some point in their lives. The condition interferes with daily activity in about 3% to 5% of the affected population.

Tinnitus becomes a problem when it affects quality of life. The impact of a problematic tinnitus ranges from a mild annoyance to a completely debilitating condition with significant social and economic consequences. The most common tinnitus-related complaints are:

difficulty understanding speech and television, poor appreciation of music, and trouble using the phone;
interference with work duties, social activities, and family responsibilities;
effects on general health including sleep disturbances, fatigue, headaches and ear pain;
emotional and cognitive problems including annoyance, irritation, inability to relax, anxiety, depression, suicide ideation and difficulty concentrating.

A problematic tinnitus has both auditory and non-auditory (emotional) components. The auditory component involves the perception of the sound of tinnitus generated by the brain (auditory cortex) in response to disturbances within the auditory system. When hearing loss is present, the brain receives reduced information from the ears. The brain adapts to this change by compensating for the lack of information. In an effort to fill in the blanks, the auditory cortex augments its processing activity. The tinnitus or phantom sound heard is essentially the perception of this increased activity.

Even with normal hearing ears, the brain can receive incomplete information. Scientists have observed abnormalities with the delicate structures of the cochlea (inner ear) such as the outer hair cells and auditory nerve fibres that don’t always show up on a clinical audiogram. This phenomenon is referred to as hidden hearing loss or cochlear synaptopathy.

The non-auditory component involves the emotional reaction to the sound of tinnitus. The annoyance experienced with tinnitus is the result of negative thoughts, fears, and worries associated with the experience of tinnitus. Is my tinnitus going to get worse? Will I be able to go back to work? Will I be able to enjoy silence again? What if I lose all hearing in my good ear? An emotional response is triggered when the brain starts focusing a significant amount of attention onto the tinnitus. The negative thoughts associated with tinnitus lead to distress, which increases attention and monitoring of tinnitus resulting ultimately in a more noticeable and intrusive tinnitus. This is what is referred to as the vicious cycle of problematic tinnitus. The brain temporarily loses its ability to filter out the harmless sound of tinnitus before it reaches consciousness. Tinnitus becomes problematic when natural habituation mechanisms are held back by the negative experience and fears associated with tinnitus.

Habituation is a simple form of learning in which we progressively stop paying attention to annoying sensory information. Habituation happens all the time. For example, the loud ticking of a grandfather clock in a quiet room doesn’t seem as resounding after a while and starts fading in the background. We forget about the humming noise coming from the ventilation system until it stops working. Habituation is also why some people can live near a train station, the highway or an airport. In time, the brain ceases to respond to these sounds as they are perceived as non- threatening, familiar and meaningless.

The good news is that there are evidence-based treatments designed to assist habituation of a problematic tinnitus. It is possible to retrain the brain to no longer react to tinnitus and bothersome environmental sounds.

Most tinnitus patients seen in today’s audiology clinic present with a subjective tinnitus, some form of decreased sound tolerance and hearing loss. There are comprehensive management programs currently dispensed by audiologists specialized in these hearing-related disorders that facilitate tinnitus habituation and desensitization of the auditory system to bothersome environmental sound(s). The most commonly used are Tinnitus Retraining Therapy, Progressive Tinnitus Management, and Cognitive Behavioral Therapy.

As an audiologist at the Canadian Hearing Society providing services to patients with tinnitus and decreased sound tolerance, I am often asked what methods of treatment I use in my practice. I am a firm believer in the Tinnitus Retraining Therapy (TRT) approach. Most of the counselling material and assessment and management protocols I use come from TRT. More specifically, TRT is based upon the idea that structures in the brain other than the auditory system are involved in the development of a problematic tinnitus. The limbic and autonomic nervous systems are believed to be the primary and dominant non-auditory brain systems responsible for tinnitus annoyance and distress while the auditory system plays a secondary role.

TRT was developed by Dr. Pawel Jastreboff (Research Neuroscientist), Dr. Jonathan Hazell (ENT Specialist) and Jacqui Sheldrake (Clinical Audiologist) in the 1990s. TRT combines the use of directive counselling sessions and fitting of sound therapy devices such as ear-level sound generators and hearing aids. The counselling component aims at demystifying tinnitus/ hyperacusis and creating a new frame of reference for thinking about the troublesome condition. The sound therapy component is designed to provide enrichment of the auditory background noise, reduce the audibility of tinnitus and improved audibility of sounds difficult to hear for patients with hearing loss.

A comprehensive audiological assessment is essential for the success of TRT. The assessment includes a detailed case history designed to investigate causes, characteristics and progression of tinnitus and general physical and emotional health. A thorough hearing examination is also performed to assess patient’s hearing health and associated hearing loss and decreased sound tolerance. It is crucial to consider the entire person as many internal and external factors can not only cause tinnitus but also aggravate its perception and experience.

If you are struggling with a problematic tinnitus, inquire about comprehensive management programs offered by your community Audiology and Psychology clinics. Let a professional help you live a life free of tinnitus burden.

Dany Pineault

Dany Pineault completed his Doctor of Audiology (Au.D.) at A.T. Still University. He has been an audiologist for 25 years and has extensive clinical experience in the assessment and management of problematic tinnitus and decreased sound tolerance. He currently practices as a clinical audiologist at the Canadian Hearing Society, the largest non-profit hearing healthcare organization of its kind in North America and is also a research advisor for Statistics Canada. He recently co-authored the Tinnitus in Canada paper (Ramage-Morin P, Banks R, Pineault D and Atrach M, 2019).

Dany is an assistant adjunct professor at A.T. Still University. He teaches the Tinnitus and Hyperacusis course to students enrolled in the Post-Professional Doctor of Audiology program and is an off-campus preceptor supporting Canadian University Audiology Programs (e.g.: University of British Columbia, Western University, Dalhousie University and l’Université d’Ottawa).

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Hearing Rehabilitation in Patients with Vestibular Schwannomas

admin — Mon, 08 Apr 2019 20:59:24 +0000

Hearing Rehabilitation in Patients with Vestibular Schwannomas admin Mon, 04/08/2019 - 16:59

Vestibular schwannomas (a.k.a. acoustic neuromas) are slow-growing and benign tumours arising from the balance (vestibular) nerve. Most patients present with progressive symptoms of hearing loss, tinnitus, aural fullness, and imbalance. Over 90% of vestibular schwannomas are unilateral. Bilateral tumours almost exclusively occur in patients with Neurofibromatosis type 2 (NF2). Most patients with small and stable tumours can be observed. For larger or growing tumours, surgical resection or radiation are both effective in achieving tumour control. With any treatment strategy, patients are confronted with hearing loss and hearing rehabilitation in every stage of the disease is, therefore, an essential part of our treatment.

Hearing loss can be divided into two types: conductive hearing loss and sensorineural hearing loss. In a normal hearing ear, sound waves travel through the ear canal towards the eardrum. The eardrum and the middle ear bones (ossicles) transduce the sound energy to the hearing organ, the cochlea. In conductive hearing loss, sound waves are hindered to reach the cochlea by either obstruction in the ear canal or conditions affecting the middle ear or ossicles. Hearing loss caused by conditions in the cochlea or the vestibulocochlear nerve results in sensorineural hearing loss.

With pure tone audiometry (hearing testing) we can differentiate between these two types of hearing loss. Auditory thresholds are assessed by presenting stimuli via headphones and bone oscillators. With the headphones the entire auditory pathway is assessed, while with the bone oscillators the sound energy is transmitted through the vibration of the skull directly to the cochlea, bypassing the middle ear and the ossicles. Combining these two thresholds gives us an impression of the degree and type of hearing loss, i.e. conductive, sensorineural or a combination of both. Besides the pure tone audiogram, we routinely also perform tests of speech discrimination or speech understanding.

In someone with a unilateral vestibular schwannoma, we typically see a sensorineural hearing loss in the affected ear and normal hearing thresholds in the other ear. An asymmetric sensorineural hearing loss on the audiogram is, therefore, one of the reasons to perform additional imaging or additional hearing testing (auditory brainstem response or ABR) to identify or exclude a vestibular schwannoma. In patients with sensorineural hearing loss due to conditions in the cochlea, like excessive noise exposure, the patient’s speech discrimination ability is usually retained. In the typical patient with a vestibular schwannoma, the speech discrimination is poorer than what is expected based on the hearing loss measured with the pure tone audiogram. The presence of the tumour on the vestibulocochlear nerve leads to a distortion of speech.

Expected Natural History of Hearing

The best hearing outcomes occur in patients who are able to have their tumours simply followed with serial MRI scans. In these people, the hearing will remain the best the longest. Unfortunately, over time the hearing can deteriorate, even if the tumour does not change in appearance on subsequent MRI scans. In whom the hearing will deteriorate and in whom it will not is not possible to predict at this time.

Radiation therapy can sometimes stop a tumour from growing and preserve residual hearing. This is particularly possible if the radiation can be directed at the tumour while avoiding the cochlea. Similarly, it is sometimes possible to surgically remove the tumour and preserve the residual hearing. This is somewhat dependent on the size and the location of the tumour, but predictable preservation of hearing even in small, ideally situated tumours is not possible. In no instance is the hearing improved with treatment of the tumour.

Hearing Rehabilitation

Rehabilitation of the patient’s hearing loss is important at every stage. Patients with a mild to moderately severe hearing loss in one ear might benefit from a hearing aid. This hearing aid will amplify the sound enhancing their hearing ability. However, patients with severe-to-profound hearing loss may expect little benefit from a hearing aid on their affected side. For these patients, a contralateral routing of signals (CROS) hearing aid might be a better option.

The CROS device consists of two hearing aids. On the affected side, the hearing device consists primarily of a microphone that picks up the sound and transmits the signal wirelessly to the receiver of a hearing aid placed on the better hearing ear. With this setup, the CROS hearing aid can pick up sound from the impaired ear and transmit it to the better hearing ear. This enables patients to hear sounds from their impaired side with their better hearing ear. A CROS hearing aid can improve hearing ability especially in a quiet environment, but not all users experience these benefits, and some have difficulties integrating the sounds from both sides. As this process takes time and is different for every individual user, a thorough trial period with a CROS device is therefore advised before committing to purchase.

A different, but more expensive option for patients with unilateral severe-to-profound hearing loss (single-sided deafness) is a bone conduction device (BCD) or bone anchored hearing aid (BAHA). This system consists of a titanium screw that is surgically fixated in the bone behind the ear, and an external bone oscillator which can be attached to the screw. The microphone, integrated into the bone oscillator, receives the sound signal. The sound processor converts this signal to an oscillation which is transmitted via the screw to the skull. The vibrating skull will activate the cochleae on both sides as they are embedded in the bone of the skull. In a patient with a unilateral severe hearing impairment due to a vestibular schwannoma, the impaired side is unable to adequately process these signals, but the vibrations are also registered by the cochlea on the normal hearing side resulting in activation of this cochlea. As with a CROS hearing aid, the BCD enables patients with unilateral hearing loss to hear sounds from their impaired side with their better hearing ear. The main difference is that the BCD uses vibration of the bone to activate the cochlea on the better hearing side, whereas the CROS hearing aid uses air conduction.

The CROS hearing aids and BCDs are only viable options for patients with a properly functioning contralateral ear. In patients with bilateral severe-to-profound sensorineural hearing loss caused by either a unilateral vestibular schwannoma and contralateral impaired cochlear functioning, or bilateral vestibular schwannomas, cochlear implants (CIs) and auditory brainstem implants (ABIs) are indicated.

A cochlear implant consists of an external sound processor and a surgically implanted device with an electrode array that is placed in the cochlea on the impaired side. The sound received by the sound processor is converted to an electrical signal which is directed through the electrode array. In the cochlea, the electric current activates nearby nerves resulting in activation of the nerve fibers which propagate this signal up to the brain. Although with vestibular schwannomas the problem is located behind the cochlea, in the vestibulocochlear nerve, cochlear implants are able to activate enough neural tissue to produce a signal, which can still be propagated through the nerve and past the tumour. Cochlear implantation in an ear with a vestibular schwannoma is mainly indicated for patients with bilateral tumours due to NF2. Because the tumour properties and extent are different in each patient, the hearing result of cochlear implantation in patients with a vestibular schwannoma is more variable than in traditional cochlear implant patients with hearing loss not due to a vestibular schwannoma.

If, despite cochlear implantation, patients do not fare well, or if the tumor is growing and requires surgical resection, an ABI might be indicated. Just like a CI, an ABI consists of an external sound processor and an internal device with an electrode array. However, this electrode array is not placed within the cochlea but instead is placed on the cochlear nucleus in the brainstem. The ABI enables patients to perceive sounds, even after surgical removal of the tumour and the vestibulocochlear nerve. However, the hearing result is in general poorer and more variable compared to cochlear implant users. Most ABI users are able to detect sounds and obtain measurable assistance with lip-reading, but a minority are able to gain significant speech understanding. Vancouver has recently been approved for an ABI program.

Conclusion

Hearing rehabilitation is an integral part of vestibular schwannoma treatment. Given the variation in hearing impairment among patients and the progressive nature of the hearing loss, an individually tailored approach is required in every stage of the disease. We advise patients to talk with their audiologists and ENT surgeons about all different rehabilitation options to aid them in their current situation and in their future.

Article by Dr. Marc Lammers, Dr. Emily Young, Dr. Jane Lea, Dr. Brian Westerberg

BC Rotary Hearing and Balance Centre, Division of Otolaryngology, St. Paul’s Hospital, University of British Columbia.

Dr. Brian Westerberg, specializing in Otology and Neurotology is based at the B.C. Rotary Hearing and Balance Centre in Vancouver. He completed a Fellowship at Stanford University and a Masters in Health Care and Epidemiology at the University of British Columbia (UBC) and has served the Royal College of Physicians and Surgeons as Program Director, and member of the Examination Committee and Chair of the Specialty Committee in OHNS at UBC.

Dr. Westerberg's interest in global health is apparent in his involvement in Zimbabwe and Uganda Hearing Health Care Programs. He is a clinical professor in the Department of Surgery and Director of the Branch for International Surgical Care at UBC.

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