Hyperacusis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor : Norina Usman, M.B.B.S[2]

Overview

Hyperacusis is a condition characterized by an over-sensitivity to a specific frequency of sound or intolerance to reasonable environmental sounds. A person with hyperacusis has difficulty accepting everyday sounds; some sounds may seem offensively loud to that person but not to others. In hyperacusis, a person gives inappropriate or exaggerated responses to sounds that are neither uncomfortable nor threatening loud to an average person; even low-intensity sounds can elicit the reaction.

Classification

Based on the symptoms, hyperacusis may be classified as Cochlear and vestibular hyperacusis.

1) Cochlear hyperacusis: (the most common form of hyperacusis) presents with ear pain, annoyance, and general intolerance to any sounds that most people don't notice or consider unpleasant. Crying spells or panic attacks may result from cochlear hyperacusis. As many as 86% of hyperacusis sufferers also have tinnitus.

2) Vestibular hyperacusis: The sufferer may experience dizziness, nausea, or a loss of balance when certain pitched sounds are present.

Anxiety, stress, and phonophobia may be present in both types of hyperacusis. Someone with either form of hyperacusis may develop avoidant behavior to avoid a stressful sound situation or avoid embarrassing themself in a social case that might involve noise.

Pathophysiology

Hyperacusis can be developed because of damage to the inner ear or hearing apparatus, affecting efferent part of the auditory nerve, and fibers that come out from the brain that control sounds. In this process, tissues of the auditory nerve are damaged, though the hair cells that permit us to hear pure tones remain integral. It can be as a result of injury to the neurological system of the brain. In some cases, hyperacusis may be triggered by a vestibular disorder. Stapes hypermobility can also be one of the causes of peripheral hyperacusis. Situations that comprise paralysis of the facial nerve (i.e., Ramsay-Hunt syndrome, Bell’s palsy, and Lyme disease) are involved in the causes of the condition.Hyperacusis increases in extent during anxiety, tiredness, or stress. The mechanism involved during stress, include endogenous dynorphins release into the synaptic region underneath inner hair cells. It potentiates the neurotransmitter glutamate, triggering sound to be seeming with excessive noise.

Causes

The Common causes of hyperacusis include:

• Loud noise experience.
• Recreational and industrial noise acquaintance and noise-related hearing loss.
• Expert musicians specifically those playing rock music and exposed to extended periods of amplified sound.
• Other causes that can lead to hyperacusis include migraine, Lyme disease, psychiatric illness such as post-traumatic stress disorder, and Williams syndrome.
• The most common cause of hyperacusis is overexposure to excessively high decibel levels (or sound pressure levels).
• Some come down with hyperacusis suddenly by firing a gun, having an airbag deploy in their car, taking ear sensitive drugs.

Other causes can be due to the following:

• Severe head trauma
• Facial nerve dysfunction (to Stapedius)
• Surgery
• Ear irrigation
• TMJ (Temporomandibular joint disorder)
• Adverse drug reaction
• Williams Syndrome
• Autism
• Bell's palsy
• Ménière's disease
• Asperger syndrome
• Superior Canal Dehiscence Syndrome
• Chronic ear infections
• Minor Head Injury
• A vestibular disorder: see below.

Differentiating hyperacusis from other diseases

On the basis of sign and symptoms hyperacusis must be differentiated from misphonia, phonophobia, tinnitus, william syndrome,lyme disease,migraine.

Diseases	Clinical manifestations						Para-clinical findings	Gold standard
	Symptoms			Physical examination
	Negative emotional reaction	Ringing in the ears	Psychiatric disorders	Hearing loss	Sound sensitivity	Loudness discomfort level
Misphonia	+	-	+	+/-	-	-	Limbic system involved	Clinical diagnosis
Phonophobia	+	-	+	+/-	-	-	Limbic system involved	Clinical diagnosis
Tinnitus	+/-	+	+	-	+	+	8th cranial nerve palsy/ auditory system involved	Audiological exam
William Syndrome	+/-	-	+/-	+	+	+	Genetic disorder	Micro-array analysis/FISH and audiological exam
Lyme Disease	+	+	+/-	+	+	+	Auditory system involved	Audiological exam
Migraine	-	+	-	-	+	+/-	Trigeminal ganglion stimulation	Clinical diagnosis

Epidemiology and Demographics

Incidence

• The incidence of hyperacusis is approximately 1 in 50,000 people.

Prevalence

• The overall prevalence of hyperacusis among children and adolescents is between 3.2% to 1.7%. In adults, prevalence rate is between 8% to 15.2%.

Age

• Hyperacusis is commonly seen in individuals with any age group.

Gender

• Hyperacusis affects men and women equally.

Race

• There is no racial predilection to hyperacusis.

Natural History, Complications, and Prognosis

Natural History

• In the case of a hyperacusis, patients can present with.

• Ear pain
• Annoyance
• Fear
• General intolerance to many sounds
• Crying spells
• Panic attacks
• Tinnitus
• Anxiety
• Stress
• Phonophobia
• Avoidant behavior
• Dizziness
• Nausea

Complications

• Common complications of hyperacusis depend on the etiology.

Prognosis

• Depending on the extent of the disease progression at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good.
• Patients with hyperacusis have profound psychological influence, patients presenting with self-harm or suicidal ideation.

Hyperausis Diagnosis

Diagnostic study of choice

Pure tone audiometry is the gold standard test for the diagnosis of hyperacusis.

• Loudness discomfort level( LDL) measured in decibels (dB); LDL decreased by 16–18 dB than the general population is diagnostic of hyperacusis.
• 95% of patients with hyperacusis have LDL ≤ 77 dB (average LDL in a normal person is 100 dB).

History and Symptoms

The hallmark of hyperacusis is sensitivity to sounds. A positive history of over-sensitivity or distress to particular sounds is suggestive of hyperacusis. The most common symptoms of hyperacusis include annoyance, ear pain, loudness, and tinnitus.

Physical Examination

Physical examination of patients hyperacusis is usually remarkable for fear, irritability, and avoidance behavior.

Laboratory Findings

There are no diagnostic laboratory findings associated with hyperacusis.

CT scan

There are no CT scan findings associated with hyperacusis.

MRI

There are no MRI findings associated with hyperacusis.

Other Diagnostic Studies

Health questionnaires may be helpful in the diagnosis of hyperacusis. Findings suggestive of hyperacusis include:

• HQ score of ≥ 22 is diagnostic of hyperacusis.
• Disability
• Functional impact
• Psychological factors
• Impacted quality of life

Treatment

The most common treatment for hyperacusis is retraining therapy that includes:

• Tinnitus Retraining Therapy (TRT), a treatment originally used to treat tinnitus, uses broadband noise to treat hyperacusis. By listening to broadband noise at soft levels for a disciplined period of time each day, patients can rebuild (i.e., re-establish) their tolerances to sound.
• Pink noise can also be used to treat hyperacusis.

Another possible treatment include:

Non- pharmacological therapy	Surgical Treatment	Alternative treatments
Cognitive Behavioral Therapy	Round window reinforcement	Excercise, yoga,meditation
Tinnitus retraining therapy (TRT)	Oval window reinforcement	Massage,relaxing therapy,hypnosis
Directive Counselling		Vitamin and supplements

People

• Stephen Merritt, of The Magnetic Fields, suffers from this condition.

See also

• Hearing impairment
• Tinnitus

External links

• AIT Institute for Auditory Integration Training. AIT helps remediate hyperacute hearing
• The Hyperacusis Network
• Tinnitus & Hyperacusis Center by Pawel J. Jastreboff
• The Tinnitus and Hyperacusis Centre, London UK