Hyperacusis is the perception of an unusual auditory sensitivity to some environmental noises or tones. It is an abnormal condition in which the complex electrical signals generated by sound vibrations are misinterpreted, confused, or exaggerated.

 

Symptoms of hyperacusis can range from a mild sense of unease to a complete loss of balance or upright posture with severe ear pain. In serious cases, it can cause seizure-like activity in the brain.

 

With cochlear hyperacusis, subjects feel ear pain, discomfort, annoyance, or some other emotional reaction when certain sounds are heard, including those that are very soft or high-pitched. In vestibular hyperacusis, exposure to sound can result in falling or a loss of balance or postural control. Such disturbances have been called by various names, including Tullio’s syndrome and audiogenic seizure disorder. Some of the same reactions as with cochlear hyperacusis can also occur, along with sudden severe vertigo or nausea. In some cases, vestibular hyperacusis can affect the autonomic system and cause problems such as loss of consciousness, mental confusion, nausea, or extreme fatigue. In both cochlear and vestibular hyperacusis, headache is common.

 

Causes: Hyperacusis can be associated with auto-immune disorders, traumatic brain injury, metabolic disorders, and other conditions, although it is often ascribed to psychological conditions rather than being recognized as a physiologic symptom of cochlear or vestibular damage. The physiologic conditions underlying these symptoms cannot be identified with certainty because of difficulties involved with studying the very small inner ear structures without damaging them.

 

A suspected cause of cochlear hyperacusis involves a loss of the regulatory function provided by the system that conducts impulses along the auditory neural pathways. Thus, for example, the sound of a passing car might be interpreted as comparable to the roar of a jet engine. Other possible causes involve brain-chemistry dysfunction or head trauma that damages the chain of tiny bones in the middle ear that amplify sound and help transmit vibrations to the inner ear fluid.

 

In vestibular hyperacusis, damage to the nerve cells in the balance system is suspected, possibly from head injury, metabolic disruptions due to chemical ingestions (e.g., medications or anesthesia), or circulatory changes due to heart disease or artery blockages. In addition, autoimmune disease, which can be triggered by many different causes, can harm the balance organ.

 

Testing and treatment: While special audiologic tests can reveal the presence and severity of cochlear hyperacusis, and help define treatment, diagnosis and treatment of vestibular hyperacusis is less defined. When vestibular hyperacusis is recognized, the treatment protocols vary widely and have included a low-salt diet combined with anti-nausea drugs, and the introduction of anti-inflammatory medicines directly into the cochlear/vestibular system using catheters.

From VEDA publication C-2, Cochlear Hyperacusis & Vestibular Hyperacusis