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.
Disorders in this issue:
HI 4.02 Auditory Neuropathy
(also known as Auditory Dyssynchrony)
Disability Category: Hearing Impaired
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).
VI 3.04- Anophthalmia
Disability Category: Visual Impairment
Definition
Anophthalmia is the absence of one or both eyes. This rare disorder develops during pregnancy and can be associated with other birth defects (National Eye Institute, 2005c).
Explanation
Causes of these conditions may include genetic mutations and abnormal chromosomes. Researchers also believe that environmental factors, such as exposure to X-rays, chemicals, drugs, pesticides, toxins, radiation, or viruses, increase the risk of anophthalmia and microphthalmia, but research is not conclusive. Sometimes the cause in an individual patient cannot be determined (National Eye Institute, 2005c).
VI 3.04a-Consecutive or Degenerative Anophthalmia
In degenerative anophthalmia the eye started to form and, for some reason, degenerated. One reason for this occurring could be a lack of blood supply to the eye.
VI 3.04b-Primary Anophthalmia
Primary anophthalmia is a complete absence of eye tissue due to a failure of the part of the brain that forms the eye.
VI 3.04c-Secondary Anophthalmia
In secondary anophthalmia the eye starts to develop and for some reason stops, leaving the infant with only residual eye tissue or extremely tiny eyes which can only be seen under close examination.
VI 3.05-Microphthalmia
Disability Category: Visual Impairment
Definition
Microphthalmia is a disorder in which one or both eyes are abnormally small (National Eye Institute, 2005c).
Explanation
Children with microphthalmia may have some residual vision (limited sight). In these cases, the good eye can be patched to strengthen vision in the microphthalmic eye. A prosthesis can be made to cap the microphthalmic eye to help with cosmetic appearance, while preserving the remaining sight (National Eye Institute, 2005c).
Download this Issue
To Download a PDF file version of this Issue of the NASET’s Lesser Known Disorders in Special Education Series –CLICK HERE
