Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.

Aggressive behavior can denote verbal aggression, physical aggression against objects, physical aggression against people, and may also include aggression towards oneself.

A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.

A seizure is an intermittent abnormality of nervous system physiology characterised by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Severe mental retardation is defined as an intelligence quotient (IQ) in the range of 20-34.

Difficulty in social interactions related to an impairment of characteristics such as eye contact, smiling, appropriate facial expressions, and body postures and characterized by difficulty in forming peer relationships and forming friendships.

Abnormal coordination of muscles involved in speech.

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

A type of Developmental delay characterized by a delay in acquiring motor skills.

Complete lack of development of speech and language abilities.

A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.

Head circumference below 2 standard deviations below the mean for age and gender.