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:
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Aicardi Syndrome (Aicardi-Goutieres syndrome)
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Developmental Disorders affecting brain formation
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Sensory Integration Disorders
OHI 1.00-Aicardi Syndrome (Aicardi-Goutieres syndrome)
Disability Category – Other Health Impaired
Definition
Aicardi Syndrome is a rare genetic disorder identified by the French Neurologist, Dr. Jean Aicardi in 1965. The number of identified cases of girls with Aicardi syndrome is approximately 300 – 500 worldwide. It is characterized by the partial or complete absence of the structure that links the two hemispheres of the brain, the corpus callosum.
The disorder affects only girls. Onset of Aicardi Syndrome generally begins between the ages of 3 and 5 months with infantile spasms, a type of childhood seizure.
Diagnostic Symptoms
Symptoms include seizures, mental retardation and lesions on the retina of the eye that are specific to the disorder. Aicardi Syndrome may be associated with other brain defects such as a smaller than average brain and cavities or gaps in the brain filled with cerebrospinal fluid. There is no cure for Aicardi Syndrome nor is there a standard course of treatment. Treatment generally involves medical management of seizures and programs to help parents and the child cope with developmental delays.
Further Key Points
The prognosis for girls with Aicardi Syndrome varies according to the severity of their symptoms. The known age range of affected children is from birth to the mid 20’s.
MR 3.00-Developmental Disorders affecting brain formation
Disability Category – Mental Retardation
Definition
These disorders involve structural malformations and developmental defects and their related effects on the central nervous system. Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. Cephalic is a term that means “head” or “head end of the body.” Congenital means the disorder is present at, and usually before, birth (Wikipedia, 2005)
MR 3.01-Anencephaly
Anencephaly is a defect in the closure of the neural tube during fetal development. The neural tube is a narrow channel that folds and closes between the 3rd and 4th weeks of pregnancy to form the brain and spinal cord of the embryo. Anencephaly occurs when the “cephalic” or head end of the neural tube fails to close, resulting in the absence of a major portion of the brain, skull, and scalp. Infants with this disorder are born without a forebrain (the front part of the brain) and a cerebrum (the thinking and coordinating part of the brain). The remaining brain tissue is often exposed–not covered by bone or skin. A baby born with anencephaly is usually blind, deaf, unconscious, and unable to feel pain. Although some individuals with anencephaly may be born with a rudimentary brain stem, the lack of a functioning cerebrum permanently rules out the possibility of ever gaining consciousness. Reflex actions such as breathing and responses to sound or touch may occur.
The cause of anencephaly is unknown. Although it is thought that a mother’s diet and vitamin intake may play a role, scientists believe that many other factors are also involved.
Recent studies have shown that the addition of folic acid (vitamin B9) to the diet of women of childbearing age may significantly reduce the incidence of neural tube defects. Therefore it is recommended that all women of childbearing age consume 0.4 mg of folic acid daily.
There is no cure or standard treatment for anencephaly. Treatment is supportive. The prognosis for babies born with anencephaly is extremely poor. If the infant is not stillborn, then he or she will usually die within a few hours or days after birth (National Institute of Neurological Disorders and Stroke, 2004).
MR 3.02-Colpocephaly
Colpocephaly is a disorder in which there is an abnormal enlargement of the occipital horns–the posterior or rear portion of the lateral ventricles (cavities or chambers) of the brain. This enlargement occurs when there is an underdevelopment or lack of thickening of the white matter in the posterior cerebrum. Colpocephaly is characterized by microcephaly (abnormally small head) and mental retardation. Other features may include motor abnormalities, muscle spasms, and seizures.
MR 3.03-Holoprosencephaly
Holoprosencephaly is a disorder characterized by the failure of the prosencephalon (the forebrain of the embryo) to develop. During normal development the forebrain is formed and the face begins to develop in the fifth and sixth weeks of pregnancy. Holoprosencephaly is due to the effects of a failure of the embryo’s forebrain to divide to form bilateral cerebral hemispheres (the left and right halves of the brain), causing defects in the development of the face and in brain structure and function.
MR 3.04-Hydranencephaly
Hydranencephaly is a rare condition in which the cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid. Usually the cerebellum and brainstem are formed normally. An infant with hydranencephaly may appear normal at birth. The infant’s head size and spontaneous reflexes such as sucking, swallowing, crying, and moving the arms and legs may all seem normal. However, after a few weeks the infant usually becomes irritable and has increased muscle tone (hypertonia).
MR 3.05-Hydrocephalus
Hydrocephalus is a condition in which the primary characteristic is excessive accumulation of fluid in the brain. Although hydrocephalus was once known as “water on the brain,” the “water” is actually cerebrospinal fluid (CSF) — a clear fluid surrounding the brain and spinal cord. The excessive accumulation of CSF results in an abnormal dilation of the spaces in the brain called ventricles. This dilation causes potentially harmful pressure on the tissues of the brain. Hydrocephalus may be congenital or acquired. Congenital hydrocephalus is present at birth and may be due to the effects of either environmental influences or genetic predisposition. Acquired hydrocephalus develops at the time of birth or at some point afterward. Acquired hydrocephalus can affect individuals of all ages and may be due to the effects of injury or disease. The causes of hydrocephalus are not all well understood. Symptoms of hydrocephalus vary with age, disease progression, and individual differences in tolerance to CSF. In infancy, the most obvious indication of hydrocephalus is often the rapid increase in head circumstance or an unusually large head size.
In older children and adults, symptoms may include headache followed by vomiting, nausea, papilledema (swelling of the optic disk, which is part of the optic nerve), downward deviation of the eyes (called “sunsetting”), problems with balance, poor coordination, gait disturbance, urinary incontinence, slowing or loss of development, lethargy, drowsiness, irritability, or other changes in personality or cognition, including memory loss. Hydrocephalus is diagnosed through clinical neurological evaluation and by using cranial imaging techniques such as ultrasonography (is an ultrasound-based diagnostic imaging technique used to visualize subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions.), computer tomography (CT), magnetic resonance imaging (MRI), or pressure-monitoring techniques.
Hydrocephalus is most often treated with the surgical placement of a shunt system. This system diverts the flow of CSF from a site within the central nervous system to another area of the body where it can be absorbed as part of the circulatory process. A shunt is a flexible but study silastic tube. A limited number of patients can be treated with an alternative procedure called third ventriculostomy (Endoscopic third ventriculostomy (ETV) is an alternative to shunt placement). In this procedure, a small hole is made in the floor of the third ventricle, allowing the CSF to bypass the obstruction and flow toward the site of resorption around the surface of the brain.
The prognosis for patients diagnosed with hydrocephalus is difficult to predict, although there is some correlation between the specific cause of hydrocephalus and the patient’s outcome. Prognosis is further complicated by the presence of associated disorders, the timeliness of diagnosis, and the success of treatment. Affected individuals and their families should be aware that hydrocephalus poses risks to both cognitive and physical development. Treatment by an interdisciplinary team of medical professionals, rehabilitation specialists, and educational experts is critical to a positive outcome. Many children diagnosed with the disorder benefit from rehabilitation therapies and educational interventions, and go on to lead normal lives with few limitations (National Institute of Neurological Disorders and Stroke, 2004).
MR 3.06-Iniencephaly
Iniencephaly is a rare neural tube defect that combines extreme retroflexion (backward bending) of the head with severe defects of the spine. The affected infant tends to be short, with a disproportionately large head. Diagnosis can be made immediately after birth because the head is so severely retroflexed that the face looks upward. The skin of the face is connected directly to the skin of the chest and the scalp is directly connected to the skin of the back. Generally, the neck is absent.
MR 3.07-Lissencephaly
Lissencephaly, which literally means “smooth brain,” is a rare brain formation disorder characterized by microcephaly and the lack of normal convolutions (folds) in the brain. It is due to the effects of defective neuronal migration, the process in which nerve cells move from their place of origin to their permanent location.
MR 3.08-Megalencephaly
Megalencephaly, also called macrencephaly, is a condition in which there is an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the infant or child. Head enlargement may be evident at birth or the head may become abnormally large in the early years of life.
MR 3.09-Microcephaly
Microcephaly is a neurological disorder in which the circumference of the head is smaller than average for the age and gender of the infant or child. Microcephaly may be congenital or it may develop in the first few years of life. The disorder may stem from a wide variety of conditions that cause abnormal growth of the brain, or from syndromes associated with chromosomal abnormalities.
MR 3.10-Porencephaly
Porencephaly is an extremely rare disorder of the central nervous system involving a cyst or cavity in a cerebral hemisphere. The cysts or cavities are usually the remnants of destructive lesions, but are sometimes the result of abnormal development. The disorder can occur before or after birth.
LD 9.00-Sensory Integration Disorders
Disability Category – Learning Disabilities
Definition
Sensory Integration theory is based on the work of Dr Jean A. Ayres. It is based on the premise that the primary building blocks of the central nervous system are the senses, particularly the special senses – vestibular, tactile, and proprioception. All other skills are complex processes based on a strong foundation of sensory integration.
To put it simply sensory integration is the ability to take in, sort out, and connect information from the world around us in an organized manner.
LD 9.02- Proprioceptive perceptual problem type
Individuals with this disorder have trouble knowing where one is in space. A person with this problem might not be able to tell the position of her limbs with her eyes closed. The proprioceptive system refers to components of muscles, joints, and tendons that provide a person with a subconscious awareness of body position. When proprioception is functioning efficiently, an individual’s body position is automatically adjusted in different situations; for example, the proprioceptive system is responsible for providing the body with the necessary signals to allow us to sit properly in a chair and to step off a curb smoothly. It also allows us to manipulate objects using fine motor movements, such as writing with a pencil, using a spoon to drink soup, and buttoning one’s shirt. Some common signs of proprioceptive dysfunction are clumsiness, a tendency to fall, a lack of awareness of body position in space, odd body posturing, minimal crawling when young, difficulty manipulating small objects (buttons, snaps), eating in a sloppy manner, and resistance to new motor movement activities (Rasmussen, 1995).
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