Issue # 55

Lesser Known Disorders

Each issue of this series contains at least three lesser known disorders. Some of these disorders may contain subtypes which will also be presented. You will also notice that each disorder has a code. These codes represent the coding system for all disabilities and disorders listed in the Educator’s Diagnostic Manual(EDM) Wiley Publications.

HI – 2.03- Otosclerisos

Disability Category: Hearing Impaired

Definition

Otosclerosis is a condition of the middle ear which causes hearing loss that gets worse over time. Unlike hearing loss resulting from damage to the inner ear, the hearing loss from otosclerosis is often reversible. The name otosclerosis comes from the Greek words for “hard” (scler-o) “ear” (oto). This is because otosclerosis is a disorder which causes a hardening of the bones of the middle ear (Harris, 2000)

 

Explanation

Otosclerosis can cause different types of hearing loss, depending on which structure within the ear is affected. Otosclerosis usually affects the last bone in the chain, the stapes, which rests in the entrance to the inner ear (the oval window). The abnormal bone fixates the stapes in the oval window and interferes with sound passing waves to the inner ear.

Hearing loss is the most frequent symptom of otosclerosis. The loss may appear very gradually. Many people with otosclerosis first notice that they cannot hear low-pitched sounds or that they can no longer hear a whisper. In addition to hearing loss, some people with otosclerosis may experience dizziness, balance problems, or tinnitus(National Institute on Deafness and Other Communication Disorders, 1999).

 

HI 2.03a-Classic Otosclerosis

A type of Otosclerosis in which the stapes is immobilized by a spongiotic growth along the footplate. Classic otosclerosis has traditionally been addressed through surgical management(Bukowski, J., 2004).

 

HI 2.03b-Cochlea Otosclerosis

A type of Otosclerosis that spreads to the inner ear a sensori-neural hearing impairment may result due to interference with the nerve function (New York Eye and Ear Infirmary, 2005).

 

HI 2.03c Stapedial Otosclerosis

A type of Otosclerosis that spreads to the stapes or stirrup bone, the final link in the middle ear transformer chain. The stapes rests in a small groove, the oval window, in intimate contact with the inner car fluids. Anything that interferes with its motion results in a conductive hearing impairment(New York Eye and Ear Infirmary, 2005).

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      HI- 3.00- Mixed Hearing Loss

      Disability Category: Hearing Impaired

      Definition

      Mixed hearing loss results when a conductive hearing loss occurs in combination with a sensorineural hearing loss. In other words, there may be damage in the outer or middle ear  and in the inner ear (cochlea) or auditory nerve. When this occurs, the hearing loss is referred to as a mixed hearing loss (American Speech-Language Hearing Association, 2005a).

       

      Diagnostic Symptoms

      See Conductive and Sensorinural Hearing Losses

      Further Key Points

      With mixed hearing loss, the conductive part may be treated, but the sensorineural part is usually permanent.

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          HI – 4.00- Neurodegenerative Disorders

          Disability Category: Hearing Impaired

          Definition

          Neurodegenerative diseases are a varied assortment of central nervous system disorders characterized by the gradual and progressive loss of neural tissue or nerve cells (Kennedy Krieger Institute, 2005). These diseases can result from genetic problems, biochemical defects, viral infections, or toxic substances, but they all share the same grim story. A previously healthy child begins to deteriorate (Green, 2003)

           

          Diagnostic Symptoms

          The hallmark of these diseases is a progressive loss of speech, hearing, vision, and strength. Seizures, feeding difficulties, and loss of intellect often accompany this downhill course. And up until the last several years, they continued relentlessly until the child died (Greene, 2003).

           

          Further Key Points

          Until recently, the majority of the concerns about environmental agents have centered on their potential for causing cancer. Cancer and neurodegeneration represent opposite ends of a spectrum: whereas cancer is an uncontrolled proliferation of cells, neurodegeneration is the result of the death of cells whether due to direct killing of cells by necrosis or the delayed process of apoptosis. Attention is now being focused on environmental agents’ potential for damaging the developing and mature nervous system resulting in neurodegenerative diseases (National Institute of Environmental Health Sciences, 2005).

          Types of Neurodegenerative Disorders

           

          HI 4.01- Neurodegenerative Disorders Associated with Hunter Syndrome

           

          Definition

          Hunter syndrome is a hereditary disease in which the breakdown of a mucopolysaccharide (a chemical that is widely distributed in the body outside of cells) is defective. This chemical builds up and causes a characteristic facial appearance, abnormal function of multiple organs, and in severe cases, early death (U.S. National Library of Medicine, 2004b).

           

          Explanation

          Hunter syndrome is a hereditary disease in which the breakdown of a mucopolysaccharide (a chemical that is widely distributed in the body outside of cells) is defective. This chemical builds up and causes a characteristic facial appearance, abnormal function of multiple organs, and in severe cases, early death.

          Hunter syndrome is inherited as an X-linked recessive disease. This means that women carry the disease and can pass it on to their sons, but are not themselves afffected. Because females have two X chromosomes, their normal X can provide a functioning gene even if their other X is defective—but because males have an X and a Y, there is no normal gene to fix the problem if the X is defective (U.S. National Library of Medicine, 2004b).

           

          HI 4.02-Auditory Neuropathy (also known as Auditory Dyssynchrony)

           

          Definition

          Auditory neuropathy is a hearing disorder in which sound enters the inner ear normally but the transmission of signals from the inner ear to the brain is impaired. It can affect people of all ages, from infancy through adulthood. The number of people affected by auditory neuropathy is not known, but the condition affects a relatively small percentage of people who are deaf or hearing-impaired (National Institute on Deafness and Other Communication Disorders, 2003).

           

          Explanation

          Several factors have been linked to auditory neuropathy in children. However, a clear cause and effect relationship has not been proven. Some children who have been diagnosed with auditory neuropathy experienced certain health problems as newborns, or during or shortly before birth. These problems include jaundice, premature birth, low birth weight, and an inadequate supply of oxygen to the unborn baby. In addition, some drugs that have been used to treat medical complications in pregnant women or newborns may damage the inner hair cells in the baby’s ears, causing auditory neuropathy (National Institute on Deafness and Other Communication Disorders, 2003).

           

          HI 5.00-Sensorineural Hearing Loss

           

          Definition

          A hearing loss caused by a problem in the inner ear or auditory nerve. A sensorineural loss often affects a person’s ability to hear some frequencies more than others. This means that sounds may be appear distorted, even with the use of a hearing aid. Sensorineural losses can range from mild to profound (National Center on Birth Defects and Developmental Disabilities, 2005).

          Diagnostic Symptoms

          According to the American Speech-Language-Hearing  Association, (2005b) a sensorineural hearing loss not only involves a reduction in sound level, or ability to hear faint sounds, but also affects speech understanding, or ability to hear clearly.

          Sensorineural hearing loss can be caused by diseases, birth injury, drugs that are toxic to the auditory system, and genetic syndromes. Sensorineural hearing loss may also occur as a result of noise exposure, viruses, head trauma, aging, and tumors.

           

          Further Key Points

          Various infections can cause damage to the nerves in the cochlea, such as spinal meningitis or syphilis. The most common viruses that cause hearing loss are measles (rubella) and mumps. Viral infections in a pregnant mother can also affect the fetus. Damage to the cochlea of an unborn child also can take place when there is an Rh incompatibility with the mother or the mother has a fever (House Ear Institute, 2004). Although a small percentage of sensorineural hearing losses can be medically or surgically treated, most cannot be and are permanent in nature (Bess & Humes, 1990; cited in Gargiulio, 2004)

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