Hemipseudaoathetosis refers to pseudoathetosis on one side of the body, usually the upper limb and is most commonly caused by a lesion affecting the cuneate tract or cuneate nucleus in the cervical spine or lower brainstem (medulla) respectively.

Athetosis can vary from mild to severe motor dysfunction; it is generally characterized by unbalanced, involuntary movements of muscle and a difficulty maintaining a symmetrical posture. The associated motor dysfunction can be restricted to a part of body or present throughout the body, depending on the individual and the severity of the symptom. One of the pronounced signs can be observed in the extremities in particular, as the writhing, convoluted movement of the digits. Athetosis can appear as early as 18 months from birth with first signs including difficulty feeding, hypotonia, spasm, and involuntary writhing movements of the hands, feet, and face, which progressively worsen through adolescence and at times of emotional distress. Athetosis is caused by lesions in several brain areas such as the hippocampus and the motor thalamus, as well as the corpus striatum; therefore children during the developmental age could possibly suffer from cognitive deficits such as speech impairment, hearing loss, and failed or delayed acquirement of sitting balance.

It may be mistaken for choreoathetosis, however, these abnormal movements are relatively constant irrespective of whether the eyes are open or closed and occur in the absence of proprioceptive loss.

Athetosis is a symptom characterized by slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet and in some cases, arms, legs, neck and tongue. Movements typical of athetosis are sometimes called "athetoid" movements. Lesions to the brain are most often the direct cause of the symptoms, particularly to the

corpus striatum. This symptom does not occur alone and is often accompanied by the symptoms of cerebral palsy, as it is often a result of this disease. Treatments for athetosis are not very effective, and in most cases are simply aimed at the uncontrollable movement, rather than the cause itself.

Chorea is a continuous, random-appearing sequence of one or more discrete involuntary movements or movement fragments. Although chorea consists of discrete movements, many are often strung together in time, thus making it difficult to identify each movement's start and end point. These movements can involve the face, trunk, neck, tongue, and extremities. Unlike dystonic movements, chorea-associated movements are often more rapid, random and unpredictable. Movements are repeated, but not rhythmic in nature. Children with chorea appear fidgety and will often try to disguise the random movements by voluntarily turning the involuntary, abnormal movement into a seemingly more normal, purposeful motion. Chorea may result specifically from disorders of the basal ganglia, cerebral cortex, thalamus, and cerebellum. It has also been associated with encephalitis, hyperthyroidism, anticholinergic toxicity, and other genetic and metabolic disorders. Chorea is also the prominent movement featured in Huntington's disease.

Athetosis is defined as a slow, continuous, involuntary writhing movement that prevents the individual from maintaining a stable posture. These are smooth, nonrhythmic movements that appear random and are not composed of any recognizable sub-movements. They mainly involve the distal extremities, but can also involve the face, neck, and trunk. Athetosis can occur in the resting state, as well as in conjunction with chorea and dystonia. When combined with chorea, as in cerebral palsy, the term "choreoathetosis" is frequently used.