Timothy C. Hain, MD Page last modified: November 5, 2017
Hyperacusis defined Causes Diagnosis Treatment
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Hyperacusis is an abnormal sensitivity to sound. Katznenell and Siegel defined it as "increased sensitivity to sund .. that would not trouble a normal individual".
Other names for similar symptoms are phonophobia (fear of sounds), and misophonia (hatred of particular sound). These words are used somewhat interchangeably, without much precision. For example, hyperacusis in migraine is generally called phonophobia by neurologists. The term "pain hyperacusis" has also been introduced (e.g. Colluci, 2017), where the term "pain" has been substituted for "abnormal sensitivity". (seems like a bad definition to us)
Somewhere between 2 and 8% of the population report hyperacusis (Andersson, G., N. Lindvall, et al., 2002; Baguley et al, 2011). In our clinical practice, Chicago Dizziness and Hearing, looking at a representative subset of our patient database, out of 33 patients with hyperacusis, 14 were men, and the average age was 48. Thus hyperacusis seems to be a disorder split roughly equally among genders and being first noticed, roughly at the age of 50.
Hyperacusis can be split into categories -- loudness, annoyance, fear and pain.
Sometimes people call loudness hyperacusis, "supersonic hearing". In other words, it is not necessarily a bad thing. People with loudness hyperacusis can hear softer sounds than "normal" people. An example of this group are persons with SCD (superior canal dehiscence), who can hear internal noises (such as movement of their eyes) that other people can't.
The latter two categories are negative emotional responses generally associated with normal ability to perceive sound. In other words, these people have the same thresholds as everyone else, but they get upset earlier as the sound intensity is increased.
This is a review on hyperacusis written from the perspective of an otoneurologist (Dr. Hain). It emphasizes mechanisms for hyperacusis outside of inner ear disease.
|The structures of the inner ear.|
What causes hyperacusis ?
There are many causes of hyperacusis (Katznell and Siegel, 2001). There is not a single mechanism, and furthermore there is not a single "magic bullet" for hyperacusis.
The graph above (made with excel from made-up data), illustrates some general concepts about hyperacusis and what the terms "threshold", and "slope of perception vs. input". This graph is only meant to illustrate some general principles, and is not meant to say that everyone with, lets say, migraine, has the same picture. Also, it is not presently possible to quantify "perception" in a precise way, as perception is subjective.
Normal people (the blue line), are defined as having a perception of sound equal the sound input intensity (in decibels). Thus their threshold is 0 dB, and their slope is 1.
Persons with migraine (the orange line), have the same threshold as other people, but they perceive sounds as being louder as they really are. Thus their slope is > 1. They have a reduced dynamic range (i.e. they don't tolerate loud noises as well as normal people).
Persons with recruitment (the gray line), are people who have damage to their inner ear, and can't hear very soft sounds (thus their threshold is higher). However, like migraine patients, the slope of their perception grows more rapidly with input. This results in a reduced dynamic range for sound that they tolerate. Sounds are more often "too soft", or "too loud".
Hyperacusis with increased thresholds for sound (i.e. from ear damage)
Most hyperacusis is considered to be associated with damage to the inner ear, specifically the cochlea (the snail like thing on the right labeled '9'). However, the evidence is not strong. In our clinical experience, in hyperacusis, inner ear disease is much less common than other disorders that cause hyperacusis (e.g. migraine). Obviously, deaf people can't have hyperacusis (just as people without inner ear function don't experience motion sickness).
Thus as a general comment, there are opposed processes in hyperacusis associated with hearing loss -- the reduced hearing sensitivity makes hyperacusis less likely, and other changes, perhaps mainly related to adaptation to hearing loss, can make the remaining hearing input more annoying. As hearing loss progresses, there is less input for central circuitry associated with annoyance, and eventually loss of hyperacusis.
Inner ear hyperacusis Causes Irritability Recruitment Coincidence
When hyperacusis is accompanied by hearing loss, the association could be caused by irritability of the hair cells (such as in Meniere's disease), an increase in central gain (such a due to recruitment) or a mistake (i.e. confusion of an association with a cause). Recruitment is the jargon term used in audiology to describe the change in the input/output characteristics noted above.
In inner ear disease, loss of hearing at one frequency may be accompanied by increased sensitivity around the area of the hearing loss, resulting in hyperacusis. Thus a focal hearing loss may be more likely to cause hyperacusis due to an overly broad increase in central sensitivity. In support of this idea, Manohar et al (2017) noted that in rats given a high frequency hearing loss, they avoided low frequency noise.
According to Spyridakou et al (2012), difficulty with hearing speech in noise does not correlate with hyperacusis, but increased suppression of OAE's by noise does. This would support the conjecture that hyperacusis does not correlate with significant hearing loss, but might also relate the observation that if you can't hear something, you can't be sensitive to it.
Hyperacusis with reduced threshold to sound:
Hyperacusis occurs as in the SCD syndrome (Schmuziger, Allum et al. 2006), where people have better hearing than normal. If one can hear one's eyes move, SCD should be strongly considered. Hyperacusis for ones own eye movements -- i.e. an ability to hear ones eyes move, can also occur after surgery for tumors of the inner ear(Coad, Lockwood et al. 2001; Biggs and Ramsden 2002)
Loudness hyperacusis may occur in Bell's palsy -- here one of the small protective muscles in the ear, the stapedius, is paralyzed when the 7th nerve is damaged.
One would think that there would also be hyperacusis when the 5th nerve is damaged, paralyzing the bigger tensor tympani muscle.
Hyperacusis can also arise from damage to the nerve between the ear and brain (8th nerve, labeled 6, auditory nerve). Examples here might be hyperacusis after a sudden hearing loss (attributed to viral damage to the hearing nerve), or microvascular compression syndrome. Hyperacusis is not a problem in completely deaf people (of course).
It may be that in a few cases, the hyperacusis here is not due to recruitment, but rather due to irritability of the nerve.
The next step in the hearing cascade is the cochlear nucleus in the brainstem. Brainstem hearing disorders are rare, and it is also thought that brainstem hyperacusis is exceedingly rare. There have been a few cases reported however (Pfadenhauer, K., H. Weber, et al., 2001).
In the audiology community, the hypothesis is sometimes advanced that persons with hyperacusis have caused this problem themselves, by avoiding exposure to ordinary sounds. We find this implausible, but avoidance may add to the problem.
Furthermore, the audiology community often offers the hypothesis that "negative reinforcement caused by sound sensitivity and pain support hypervigilance, fear, and the development of psychopathology". (Colucci, 2017). The idea here, in essence, is that there is a positive feedback loop. When people are hurt by sound, they avoid sound, and as a consequence, they make themselves worse because their brain, in an attempt to hear more stuff, turns up the internal volume. We would not use this logic concerning someone who burns their hands on the stove and subsequently avoids fires, but we do with hyperacusis. Sometimes the words "breaking the cycle" is used, referring to the positive feedback loop (Colucci, 2017).
There is a large literature about using conditioning (called behavioral therapy) to reduce protective behavior patterns. One would think that CBT (cognitive behavioral therapy), would be effective in reducing distress (Juris et al, 2014)
As audiologists are unable to prescribe medications, it is not surprising that audiologists generally do not discuss medication treatment of anxiety or fear. However, physicians are allowed to prescribe medications for anxiety and depression, that can help in these situations.
Rarer sources of hyperacusis follow:
An obscure condition called "pyroluria" has been suggested to cause sensitivity to sound as well as smell and bright light. This syndrome has been discredited. The symptoms, however, are similar to migraine without headache.
Malingering of hyperacusis is also possible, as it is intrinsically a subjective symptom. See this page for more about malingering of hearing symptoms.
Persons with Williams syndrome all have hyperacusis (Klein). This pediatric syndrome is characterized by cardiac defects, varying degrees of physical and developmental delay, stellate eye pattern, possible elevated serum calcium level, and elfin/pixie facial features.
How is hyperacusis diagnosed ?
Persons with hyperacusis should be evaluated by a physician expert in ear disease, usually an otologist, neurotologist, or otoneurologist. There should be an examination of the ears. If there is also sensitivity to other sensory input (such as bright light, strong smells, motion) and/or headaches, a neurologist or otoneurologist would be the most appropriate as multiple sensory sensitivity is outside the spectrum of disease usually seen by ear doctors.
Audiogram showing low thresholds for uncomfortable noise, in patient with hyperacusis. Another audiogram showing more discomfort for high frequencies.
Hearing should be tested with an audiometer (i.e. not just tuning forks or other screeners), and the "UCL" audiogram should be obtained (uncomfortable loudness levels). Goldstein, B. and A. Shulman (1996). The UCL audiogram is a measure of discomfort from pure tones. Ideally, UCL levels should be around 80-90. Someone with hyperacusis might be around 50 as shown above. For situations where there might be misophonia (dislike of a particular sound -- perhaps an ambulance siren), one would expect that it would be more productive to measure distress due to that particular sound, but this is not an easy task and generally not undertaken.
Otoacoustic emissions may be helpful (OAE's), especially the type of OAE's that are "diagnostic" rather than screening (we call these "sweep" OAE). Contralateral suppression deficits in OAE have been reported. (Attius, 2005)
Acoustic reflexes may detect persons with paralysis of their stapedius.
A careful history should be taken, especially for migraine. Persons with migraine often have small white matter lesions that may be seen on the MRI. In addition to hyperacusis, persons with migraine often have photophobia (sensitivity to bright light), motion intolerance, sensitivity to strong smells, and sometimes even unusual cutaneous sensitivity (allodynia). The treatment approach for migraine is completely different than that for other types of hyperacusis.
A psychological assessment may detect persons who have associated anxiety, depression or obsessive compulsive personality disorder (OCD). Those with auditory hallucinations may have a psychiatric disorder such as schizophrenia. Finding these things usually does not mean that the person's hyperacusis is caused by psychiatric problems, but rather may indicate a comorbidity. Usually it results in a medication recommendation.
How Is Hyperacusis Treated ?
Medications used in treatment of Hyperacusis
Medications may occasionally help lessen the hyperacusis even though no cause can be found. In general, we are not at all enthused about medication treatment as the side effects can be substantial and the results are often unimpressive. Dobie commented that medications were similar to placebo for tinnitus (1999), aside from those that modify the persons psychological responses. We think that the same is generally true for hyperacusis.
Medications to deal with the psychological fallout of hyperacusis is often useful -- antidepressants and anti-anxiety medications can be very helpful.
- Lorazepam or clonazepam (in low doses). These are "benzodiazepines"
- Antidepressants, especially SSRI family which is also helpful for OCD
- Anti-migraine drugs: venlafaxine, topiramate, verapamil, beta-blockers, tricyclics. Venlafaxine (an SNRI/SSRI) seems especially likely to help.
- Anti-seizure drugs: carbazepine, oxcarbamazine, gabapentin
Comment. Benzodiazepines and and antidepressants probably reduce anxiety, depression, or obsessive thinking about hyperacusis. Any sort of relief, however, is important. Anti migraine drugs act by preventing migraine, which commonly has hyperacusis (called phonophobia).
There is also evidence that serotonin pathways are implicated in hyperacusis as well as migraine, and SSRIs can be helpful. (Fioreti et al, 2016) We think that these, as well as anxiety medications are often worth trying.
Anti-seizure drugs (for example gabapentin, topiramate, levetiracetam) may be effective in persons with hyperacusis due to irritable neural pathways. These may be working on similar circuitry as is helpful for migraine. Generally speaking, seizure medications that work for migraine are also mood stabilizers, so they may also be helpful there.
Baclofen has been suggested to be useful in reducing responses in brainstem hyperacusis (Szczepaniak, W. S. and A. R. Moller, 1996). We have not found baclofen to be especially helpful.
Comment: Ear plugs work by decreasing the amount of sound that the person is exposed to. This approach is generally frowned upon, because there is a feeling that wearing ear plugs over the long term will increase hyperacusis. It is thought that exposure to noise is habituating, and reducing the noise reduces the habituation effect. Nevertheless, as is the case with sunglasses when people are bothered by bright light, ear plugs or muffs can be very useful ( Sammeth, C. A., D. A. Preves, et al., 2000). Electronic noise suppression devices are used similarly, but they are less effective in reducing high-frequencies than passive methods.
Sound generators work by conditioning the nervous system to tolerate sound. They are similar in appearance to a hearing aid. Examples of maskers include the Starkey Silent-Star, and the GHI "Tranquil". These devices are readjusted every month to gradually accomplish desensitization. (Vernon, J. A, 1987).
A new treatment for hyperacusis that we have had some success with in our clinical practice in Chicago is insertion of specialized, heavy, ear tubes. With these tubes that reduce input from the higher pitches, something like semi-permanent ear plugs, some of our patients have had remarkable improvement. The improvement in hyperacusis seems to exceed the expected reduction in hearing. An example is shown below. These tubes can also be easily taken out. This is a minimally invasive approach to hyperacusis.
Audiogram prior to ear tube insertion, showing low threshold for uncomfortable noise. Audiogram post specialized ear tube insertion, showing dramatic improvement in thresholds for uncomfortable noise.
TRT (Tinnitus Retraining Therapy) is a mixture of psychotherapy and masking (for tinnitus) or sound generators (for hyperacusis). (Jastreboff, 2000) TRT is presently a popular approach. It requires considerable time commitment. The psychotherapy part of TRT might be reasonably delivered by a psychotherapist and perhaps covered by insurance.
AIT or "Auditory integration training" consists of about 20 half-hour sessions over 10 days listening to specially filtered and modulated music. It is an unproven technique, that seems unlikely to do any harm. It is somewhat costly. It is based on Guy Bernard's book Audition Égale Comportement (English translation Hearing Equals Behavior).
Psychological help: Often, anxiety or depression which accompanies hyperacusis may be as big a problem as the hyperacusis itself. In this instance, consultation with a psychologist or psychiatrist expert in this field may be helpful. CBT is a psychological technique that may be helpful.
If you can ignore hyperacusis rather than obsess about it, this may be the best way to handle it. Medications that help people with obsessive compulsive disorder (such as the SSRI family) may be helpful.
Surgery is rarely used for treatment of hyperacusis, in essence, because it is usually just a very expensive earplug that requires anesthesia. Most people are unwilling to give up their hearing to eliminate hyperacusis. Nevertheless, in persons where hearing is unusable, surgery has been reportedly successful. (Cherry and Brown ,1996).
Silverstein reported using "oval and round window reinforcement) for hyperacusis (Silverstein et al, 2016). This is a variant of a permanent ear plug. We think that the use of weighted PE tubes is more logical (see below).
We have encountered a few patients who had hyperacusis after loud noise, respond very well to a PE tube. We think that this is more likely than not due to treatment of an oval window fistula in these patients. We have also had patients in whom we do not suspect a fistula respond well to specialized tubes (see below).
We have had several patients respond positively to use of a special PE tube, designed to be heavier than normal. This dampens sound -- basically another permanent earplug. These can be removed however.
There has been a single report of treatment of hyperacusis via purposeful reduction of hearing via surgery to disrupt the ossicular chain (so-called "disarticulation"). This method of treatment would necessarily sacrifice hearing, but is potentially reversible. We think that it would be best to avoid this surgery unless symptoms are extremely severe, as in essence it involves causing deafness.
As of 2017, there were about 144 papers on PUBMED with hyperacusis in their title. Although there are many more with hyperacusis as a keyword, this is a relatively small amount of research effort.