APA Dictionary of Psychology

a hereditary, progressive form of ataxia (muscular incoordination) that results from the degeneration of nerves in the spinal cord and nerves that connect the spinal cord to the arms and legs. Symptoms typically appear in childhood or early adolescence and may include clumsiness, balance problems, difficulty walking, unsteady gait, slurred speech, hearing and vision loss, and rapid involuntary eye movements. [Nikolaus Friedreich (1825–1882), German neurologist]