At birth, the prevalence of significant hearing loss is approximately one in 3,000. By age 70 the prevalence increases to approximately one in three. There are a variety of causes of hearing loss.
There are two major types of hearing loss: conductive hearing losses linked to disorders of the external and middle ear and sensorineural hearing losses caused by problems in the inner ear, auditory nerve and associated brain structures.
People with hearing loss may complain of a sense of fullness or pressure in their ears and at times a ringing noise (tinnitus).
Conductive hearing loss: Any interference with the transmission of sound through the external ear canal, eardrum, middle ear or the ossicles – the bones of the middle ear – may produce a conductive hearing loss. This includes a wide variety of disorders including:
- Blockage of the ear canal from wax
- Inflammatory closure of the external ear canal
- New bone growth in the ear canal
- Perforations or scarring of the eardrum
- Fluid buildup or other disorders of the middle ear
- Fusion or erosion of the middle ear bones due to congenital malformation, trauma, infection or otosclerosis
Sensorineural hearing loss: Any disorder or damage to the inner ear or auditory nerve can produce sensorineural hearing loss, also called "nerve deafness." Among the most common causes are:
- Toxic noise exposure (acoustic trauma)
- Genetic disorders resulting either in congenital (present at birth) hearing loss or progressive loss with age
- Damage by drugs (ototoxicity)
- Infections or immune system disorders
- Tumors of the inner ear or auditory nerve or other neurologic diseases.
Sensorineural hearing loss may be present at birth, may occur later in life either suddenly – such as in sudden sensorineural hearing loss – or progressively. Most progressive loss advances slowly over a number of years, but in rare cases it may progress over days or months, usually a sign of a more urgent problem.
Treatment of hearing loss: A wide variety of treatment and rehabilitative options is available for hearing loss. For example, many cases of conductive hearing loss can be corrected medically or surgically to restore normal or near-normal hearing.
While the options for medically reversing sensorineural hearing loss are much more limited, the possibility of hearing restoration is improving, especially in the case of sudden sensorineural hearing loss and immune-mediated (autoimmune) sensorineural hearing loss.
Hearing aids and other listening devices are often very helpful in improving irreversible sensorineural loss. For individuals with deafness that a hearing aid will not improve, some will benefit from a cochlear implant – a device placed surgically in the inner ear to bypass the damaged parts – can often restore useful hearing.
Our sense of balance results from the integration of information from the inner ear, eye and sense organs in our limbs, muscles and skin.
There is a long list of disorders which are known to affect the inner ear and which may produce short-term or long-term disorders of balance. Examples include:
- Meniere's disease
- Benign Paroxysmal Positional Vertigo (BPPV)
- Degenerative disorders of the balance organs
- Drug toxicity
- Inner ear trauma from head injury or sudden pressure changes
- Viral inflammation
The first step in managing a balance disorder is to make a proper diagnosis. This can often require evaluation by an Otologist, Neurologist and Otoneurologist, hearing testing (audiometry), vestibular function testing, and imaging studies such as CT or MRI scanning. After proper diagnosis, balance disorders may be treated by a wide variety of medical, surgical and rehabilitative techniques.
The Mass. Eye and Ear offers a full range of these services with modern facilities, state-of-the-art equipment,and outstanding personnel.
The facial nerve reaches the muscles of the face through the internal auditory canal, the mastoid portion of the skull and the middle ear. Disorders of the facial nerve may cause weakness and paralysis of the face, weakness of eye closure, droop of the brow or lip or abnormal twitching or distortion of the face.
Because of the facial nerve’s long course through the ear, problems in ear can affect the nerve, for example ear infection, injury and tumors. After proper diagnosis, there are a variety of medical and surgical treatments that may reverse or at least improve deformity and dysfunction caused by facial nerve disorders.
Infections of the ear are a relatively common problem. They may occur anywhere in the ear including the external canal (otitis externa, commonly called swimmer's ear), the middle ear (otitis media), the mastoid portion of the skull, or other areas of bone surrounding these structures.
Infections of the middle ear and mastoid are particularly common in childhood following upper respiratory infections. As the name implies swimmer's ear is particularly common in the summer months or in ears that are chronically wet or irritated, as in people with eczema of the outer ear or external ear canal.
Chronic infections of the middle ear and mastoid may result in significant damage to the hearing and balance mechanisms and facial nerve and at times can spread beyond the ear to surrounding structures including the brain. One common form of this damage is cholesteatoma, a situation in which dead skin and chronic inflammation invade the ear drum into the middle ear, resulting in drum damage and erosion of the middle ear bones, with infected ear drainage, bleeding and conductive hearing loss. If left untreated, the damage can extend to the inner ear, causing sensorineural hearing loss and/or vertigo, or even into the cranial cavity and spinal fluid spaces, leading to meningitis or brain abscess. Fortunately these extreme cases are infrequent.
There are a number of tumors that can affect the external, middle and inner ear.
- Both benign and malignant lesions of the skin of the auricle (outer ear) and the auditory canal, the middle ear and mastoid portion of the skull
- Acoustic neuromas (vestibular schwannoma) is a benign tumor that actually arises from one of the vestibular nerve, often within the internal auditory canal between the ear and brain. They commonly produce a progressive hearing loss and balance problems, usually in one ear
- Glomus tumors, which are usually benign, arise in blood vessel structures in the middle ear or adjacent skull base.
Proper diagnosis by an Otologist/Neurotolgist typically includes a careful physical examination, hearing testing (audiometry), and imaging studies such as CT or MRI scanning. Once diagnosed, a variety of medical and surgical treatments are employed to cure or control the tumors.
Malformation of the external ear, ear canal, middle ear and inner ear can occur in the womb. Some may be surgically reconstructed, particularly disorders of the auricle and external and middle ear. For other disorders present at birth, specialized hearing aids or cochlear implants may be helpful in rehabilitation.