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:
LD 8.03 Visual-Spatial-Organizational Nonverbal Learning Disability
Disability Category- Learning Disability
Definition
A type of nonverbal learning disability specifically associated with difficulties in visual perception and visual imagery (Nonverbal Learning Disorders Association 2005).
Explanation
Students with Visual-Spatial-Organizational Nonverbal Learning Disabilities normally have poor visual recall and/or difficulties with spatial relations. They may get lost easily, have difficulty finding things that are in plain sight, and may not be able to tell their left from their right (Nonverbal Learning Disorders Association, 2001).
Spatial and coordination problems make printing and writing, learning math, telling time, reading and coloring maps and keeping their place on the page difficult from early grades (Wagner, 2003). By high school, more complex verbal language is based on nonverbal processes like spatial relationships (in science, for example), logical ordering, and sequencing (both skills necessary for writing essays).
Students with Visual-Spatial-Organizational Nonverbal Learning Disabilities have difficulties forming visual images, and therefore cannot revisualize something seen previously. They tend to focus on the details of what is seen, often failing to grasp the “total picture” (Thompson, 1997).
It should be noted that any medical problems associated with this child’s physical and motoric abilities have been ruled out as a primary cause of the child’s difficulties. The difficulties are in the internal processing of information, not due to a physical or motoric impairment (International Dyslexia Association, 2006).
ID 2.02 Intellectual Disability due to Colpocephaly
Disability Category- Intellectual Disability
Definition
A type of Cephalic disorder characterized by an abnormal enlargement of the occipital horns—the posterior or rear portion of the lateral ventricles (cavities or chambers) of the brain (Cerullo, 2000). This enlargement occurs when there is an underdevelopment or lack of thickening of the white matter in the posterior cerebrum (Cerebral Palsy Network, 1999; National Institute of Neurological Disorders and Stroke, 2005a).
Explanation
Colpocephaly is characterized by microcephaly (abnormally small head) and mental retardation. Other features may include motor abnormalities, muscle spasms, and seizures. Although the cause is unknown, researchers believe that the disorder results from an intrauterine disturbance that occurs between the second and sixth months of pregnancy. Colpocephaly may be diagnosed late in pregnancy, although it is often misdiagnosed as hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain). It may be more accurately diagnosed after birth when signs of mental retardation, microcephaly, and seizures are present. The prognosis for individuals with colpocephaly depends on the severity of the associated conditions and the degree of abnormal brain development (Cerebral Palsy Network, 1999; National Institute of Neurological Disorders and Stroke, 2005a).
OI 3.03-Congenital hydrocephalus
Disability Category – Other Health Impaired
Definition
Congenital hydrocephalus is present at birth, and may be due to the effects of either environmental influence during fetal development or genetic predisposition (National Institute for Neurological Disorders and Stroke, 2005c).
Explanation
The most common cause of congenital hydrocephalus is obstruction of the cerebral aqueduct—the long, narrow passageway between the third and fourth ventricle or cavity of the brain. This condition may result from a blockage, infection, hemorrhage, tumor or arachnoid cyst.
Other medical problems associated with this form of hydrocephalus are (University of San Francisco Children’s Hospital, 2002):
- Chiari malformations, an abnormality at the base of brain where the spinal column joins the skull
- Craniosynostosis, when the bones in the skull fuse together before the brain has stopped growing
- Dandy-Walker syndrome, when the fourth ventricle is enlarged because of partial or complete closure of its outlets
- Hydranencephaly, a rare condition in which the brain’s cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid
- Neural tube defects or spina bifida, when the spinal cord is exposed at birth and is often lacking cerebrospinal fluid
- Schizencephaly, an extremely rare disorder characterized by abnormal slits, or clefts, in the brain’s cerebral hemispheres
- Vein of Galen malformations, abnormal connections between arteries and the deep draining veins of the brain that develop before birth
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