Where children present with abnormal movements, consider:

• Epileptic seizures
• Tics
• Stereotypy
• Self gratification
• Chorea
• Hyperekplexia

Stereotypies are repetitive non-functional movements, typically hand flapping or twisting, body rocking, head banging/nodding, grimacing, arm flapping. As with tics, there is often a family history, and there is an association with obsessive compulsive tendencies.

They can be present in children with normal development, but are a feature of neurological disorders especially autism spectrum disorder and sensory impairment.  In these children, the movements are part of a period of introspective absorption, they make prefer such activity to conventional social interactions.

There are a number of differences from tics, although they can co-exist:

• Sterotypy presents younger, eg under 2 yrs.  Tics present from 4 onwards.
• Tics can vary over time, so grimacing moves on to  shoulder jerks, then moves on to clearing throat.  Stereotypy movements are unchanging.
• Stereotypy movements are rhythmic, rather than just a single jerk
• Tics are brief, stereotypy can be prolonged
• Tics have a premonitory sensation (although only older children may be aware)
• Tics can be suppressed with effort.  Children with stereotypy can be distracted but may resent it! (Similarly self gratification)

Excitement and stress are triggers for both.  Over time, the child usually becomes aware of social disapproval and may suppress the behaviour except in secret!

[Ulster Med J 2014;83(1):22-30]