well there is a distinction between obstructive sleep apnea and central apnea. From the little I've looked into it, obstructive is things that obstruct the airway. So, this would most likely be because of weight issues, circumference of neck, contour of air passages, etc. Central apnea however signifies some glitch within/between CNS and respiratory muscles. So, I think head trauma can very well damage parts of the CNS involved in respiration. I think this was my case. I'm sure however there are other causes of central apnea but I tend to believe that it is associated directly with that hit on the head during the swim meet. Or if not directly then at least indirectly, via post susceptibility to illness, medication to treat mental illness caused or exacerbated by head injury, etc...Or, it may be something genetic.
My aunt has cerebral palsy. She had cerebral hemorrhage around time of birth, it is believed. My grandparents believe it to be associated with Forceps. Anyways, there might be a connection there with central apnea, or not. She never learned to speak. I learned to speak later at around age of mid 3's.