The Similarities Between Misophonia and Sensory Processing Disorder: Is There a Link?
written by: Rose Kivi
• edited by: dianahardin
• updated: 5/10/2011
Misophonia and sensory processing disorder both can cause noise sensitivities that lead to anxiety and despair for sufferers. While the diagnostic criteria between the two disorders differs, they do share some similarities.
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Misophonia is a disorder that causes the sufferer to have an extreme hate of certain sounds. The particularly despised sounds vary with patients, but the common component is that hearing the sounds invokes feelings of anxiety, despair and rage. Common sounds about which misophonia sufferers complain are chewing, scratching, sniffling and tapping, among others.
Misophoniais thoughtto be a neurological condition where the auditory system in the brain processes sounds incorrectly. The auditory system processes normally harmless sounds as signs of danger and therefore invokes a "fight or flight" response in the sufferer, where the person gets an urge to escape the source of the sound that is nearly impossible to fight. In addition, the auditory system processes the offending sound as louder than it actually is, making it more noticeable to the sufferer. It is as if the ear drum is the radio and the auditory system is the volume control dial, with the volume stuck on the highest setting.
Why only certain sounds invoke a misophonia response is not completely understood. One theory is that the sufferer has noise sensitivities to certain tones only. Sounds that are at the same tone to which the person is sensitive, invoke a misophonia response. This theory is based on the fact that some misohphonia sufferers also have hyperacusis, which is a disorder where the auditory system amplifies sounds picked up by the ears.
The most commonly accepted treatment for misohponia is tinnitus retraining therapy. Dr. Jastreboff developed the tinnitus retraining therapy protocol to treat misophonia, utilizing in-the-ear broadband noise generators to retrain the auditory system to become less sensitive to sounds.
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Sensory Processing Disorder
Sensory Processing Disorder or SPD, is a neurological condition where the brain misinterprets information taken in by the senses. The disorder is commonly seen in people with autism, but is also seen in those who are not autistic. Sensory processing disorder can affect one or more of the senses, including hearing, smell, vision, touch, balance, sense of space, sense of time and movement. People with sensory processing disorder can be hypersensitive or hyposensitive to stimuli.
Sensory processing disorder is treated with occupational therapy, which utilizes activities to help the neurological system integrate with the senses so that it can properly process information. The activities in occupational therapy are designed specifically for patients, based on their particular symptoms. For example, an occupational therapist may have a patient who is hypersensitive to the feeling of clothing touching her skin, touch various textured objects to accustom the brain to processing various types of tactical stimuli. Or a patient who has trouble with balance may sit on a swing during occupational therapy. Occupational therapy is carried out in a way that feels comfortable for the patient. Activies are altered when necessary, in order to ensure a positive experience that stays within the patient's comfort zone.
In the case of noise sensitivities, a form of occupational therapy called listening therapy is used. Listening therapy aims to integrate the auditory and vestibular systems together by exposing the patient to various sounds, usually through music therapy.
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Similarities Between Misophonia and Sensory Processing Disorder
Misophonia only causes noise sensitivities, while sensory processing disorder can cause sensitivities in one or more senses. Since it is possible for sensory processing disorder to only affect the sense of hearing, though, is it possible that misophoniais indeed a sensory processing disorder or a subtype of sensory processing disorder? When asked about the possibility of a link between misophonia and sensory processing disorder, Dr. Schoen, assistant director of SPD Foundation Research and the clinical services advisor of the STAR Center, responded, "Individuals with sensory processing disorder typically have impairments in more than one sensory system. Clearly the behavioral manifestations of individuals with misophonia appear similar to those with sensory over-responsivity in the auditory domain. At the present time, the biological mechanisms and implicated structures for SPD and misophonia are not well documented and the etiologies are unknown. More research is needed to determine the similarities, differences and co-occurrence of the two conditions."
Researchers don't know enough at this time about each disorder individually, and there have not been enough studies conducted to identify a possible link. A lack of research, however, does not rule out the possibility of a link between the two disorders.
Read page 2 of this article for a continued discussion on the possibilities of a link between misophonia and sensory processing disorder and a what a link could mean.
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Why does it matter if there is a link between misophonia and sensory processing disorder? How would a link help in the treatment of the disorders? With so many people suffering from these disorders, more research is needed. The minimal research that has been conducted has failed to look for a link between the two neurological conditions that cause noise sensitivities. People with misophonia and sensory processing disorder can take a survey to help answer to the question of whether the two disorders are linked.
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Different Disorder, Same Disorder or Misdiagnosis
Dr. Schoen, assistant director of SPD Foundation Research, noted that sensory processing disorder typically involved more than one of the senses; however, typically does not mean always. Does this mean, then that misophnia is actually sensory processing disorder that only affects one sense? Do misophonia sufferers have undiagonsed sensory problems with other senses? Are the two disorders different but related? These are some of the questions that need to be answered.
We cannot say at this time if misophonia and sensory processing disorder are related or not. They may be two completely different disorders, the same disorder or somehow related. Even assuming that the two are completely different disorders, there is the possibility that some people diagnosed with misophoniahave been misdiagnosed and actually have sensory processing disorder. One woman for examplehad been diagnosed by an audiologist as having misophonia. After starting tinnitus retraining therapy, she decided the treatment exacerbated her symptoms and discontinued treatment. Another doctor, after interviewing the patient, came to the conclusion that the woman actually had sensory processing disorder. The doctor discovered that the woman had tactile sensitivities and balance problems, in addition to noise sensitivities. The woman had never complained about the other sensory problems, because her auditory sensitivities consumed all of her attention and overshadowed her other sensory problems. With a diagnosis, the woman was prescribed occupational therapy.
Since many doctors are inexperienced in both disorders -- often unaware entirely of the existence of the disorders -- receiving a correct diagnosis can be difficult.
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Why Does it Matter if Misophonia and Sensory Processing Disorder are Linked?
So why does it matter if there is a link between misophonia and sensory processing disorder? Misophonia and sensory processing disorder each have different prescribed treatments for noise sensitivities. If a link is found between the two disorders, prescribed therapies may change. Misophonia patients who have not responded positively to tinnitus retraining therapy may respond to listening therapy and other forms of occupational therapy.
Both disorders are linked in at least one way, in that they are neurological and caused by the brain misinterpreting sensory input. Discovering if the two disorders are actually the same disorder or somehow related, can help enhance the understanding of both disorders and hopefully lead to new treatments. If the disorders are not linked, can treatments be shared, since the disorders affect the same part of the brain? More research needs to be conducted to find these answers. With the limited research that is currently devoted to both of these little-known disorders, a link is not being explored. Both misophonia and sensory processing disorder cause extreme suffering. As sufferers demand new research, perhaps a link between the disorders will be looked at.
How many misophonia sufferers have other sensory processing problems that have been unidentified? How many sufferers feel they have been misdiagnosed? What treatments have sufferers undergone? What treatments were successful? People with misophnia or sensory processing disorder can help find the answers to these and other related questions by filling out an anonymous survey to help build an informational database that will be forwarded to researchers. Take the survey here.
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Tinnitus Retraining Therapy: Implementing the Neuropsyiological Model; Pawel J. Jastreboff, Johnathan W. P. Hazell; Cambridge University Press; 2004
Email Interview; Dr. Schoen, Assistant Director of the SPD Foundation Research and the Clinical Services Advisor of the STAR Center; Dec. 3, 2010
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Be heard, and help find the answers needed for a cure to noise sensitivity disorders by taking this survey.