Can enlarged tonsils in a 4 year old cause irreversible behavioral problems?

See below: If the child has obstructive sleep apnea, there is an association between sleep apnea and behavioral problems.

If sleep study : shows obstructive apnea & tonsillectomy & adenoidectomy are done, you still have to use behavior modification techniques to correct the behaviors. A child psychologist can teach you how to use time-out effectively to ignore "bad" behaviors consistently as they increase, then cease,instead of reinforcing them with negative or positive attention & how to reward "good" behaviors effectively.