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In answer to the OP comments, I needed intensive speech therapy from age 2.5 to 3.
I also have dyspraxic like organisational problems (not officially diagnosed).
There appears to be a link between autism and HMS, possibly dyslexia and HMS.
In fact it appears most neurodiverse disabilities have some link with HMS.
Personally I think they are interlinked and can cause 1 issue to impact on another.
eg train leaving 2 minutes early without me! (ASD) meant I almost became non verbal on the phone, (ASD)
my ability to read was diminished (dyslexia) and I started dropping things (dyspraxia). Also I was less able
to steer my wheelchair and the crunching sensation in my shoulders is worse (HMS).
Extreme overload can cause non communication for hours sometimes days with verbal abilities gradually
improving. I could qualify for global developmental delay.