the shaky movements and unsteady gait that result from the brain's failure to regulate the body's posture and the strength and direction of limb movements. It may be due to disease of the sensory nerves or the cerebellum. In cerebellar ataxia there is clumsiness of willed movements. The patient staggers when walking; he cannot pronounce words properly and may have nystagmus. Cerebellar (or Nonne's ) syndrome is a form of cerebellar ataxia. Friedreich's ataxia is an inherited disorder appearing first in adolescence. It has the features of cerebellar ataxia, together with spasticity of the limbs. The unsteady movements of sensory ataxia are exaggerated when the patient closes his eyes (see Romberg's sign). See also ataxia telangiectasia, tabes dorsalis (locomotor ataxia).
—ataxic adj.

an inherited (autosomal recessive) neurological disorder. Ataxia is usually noted early in life. Mental retardation, growth retardation, abnormal eye movements, skin lesions, and immune deficiency may be found. Affected individuals may develop malignant disease. A raised level of alpha-fetoprotein is found in the blood, and a key feature is the presence of prominent blood vessels visible on the sclerae of the eyes.