Alexander disease: A slowly progressive and ultimately fatal brain disorder that most commonly occurs in children. The infantile form of the disease is characterized by megalencephaly (an abnormally large head), seizures, spasticity and developmental retardation. It leads to death usually within the first decade. Patients with the juvenile and adult forms of Alexander disease typically experience ataxia and spasticity and a more slowly progressive course. The classic hallmark of all forms of Alexander disease is the presence of Rosenthal fibers, abnormal inclusions in astrocytes that contain the intermediate filament protein GFAP. Mutations in the gene for GFAP (glial fibrillary acidic protein) cause Alexander disease, the first known example of a primary genetic disorder of astrocytes, one of the major cell types in the vertebrate CNS. The disease was first described by W. Stewart Alexander, a New Zealand pathologist, in 1949.
Rosenthal fibers are homogeneous masses which form elongated tapered rods scattered throughout the cortex and white matter of the brain. Rosenthal fibers are located in the astrocytes. Demyelination (loss of myelin, the insulation around nerves) is also a prominent feature of the disease. Alexander disease is classified as one of the leukodystrophies, the diseases of the white matter of the brain.
- Alexander technique
Alexander technique: A process that teaches how to properly coordinate body and mind to release harmful tension and to improve posture, coordination and general health. The technique is named for the Australian Frederick Matthias Alexander (1869-1955) who developed it. An actor, Alexander began his career as a Shakespearean orator. He developed chronic laryngitis while performing. […]
Alexia: Loss of the ability to read or understand the written word, due either to brain damage that disconnects these functions or to temporary dysfunction caused by abnormal electrical or chemical activity in the brain.
algia: Word ending indicating pain, as in arthralgia (joint pain), cephalgia (headache), fibromyalgia, mastalgia (breast pain), myalgia (muscle pain), and neuralgia (nerve pain). Derived from the Greek algos meaning pain.
Algophobia: An abnormal and persistent fear of pain. The fear is excessive, beyond that which is expected under the circumstances, producing an anxiety reaction. From the Greek “algos” (pain) and “phobos” (fear). Note that an “algometer” is an instrument for measuring pain (it does so by gauging the smallest pressure that produces pain).
- Alice in Wonderland syndrome
Alice in Wonderland syndrome: A syndrome of distorted space, time and body image. The patient with the Alice in Wonderland syndrome has a feeling that their entire body or parts of it have been altered in shape and size. The syndrome is usually associated with visual hallucinations. The majority of patients with the syndrome have […]