Complex sentence: He noted that the children had no particular health difficulties and that their EEG results were normal, he did, however, observe that 5 of the 11 children had relatively large heads and a few were somewhat clumsy in their gait.
Split into simpler sentences: He noted that the children had no particular health difficulties and that their EEG results were normal. He did, however, observe that 5 of the 11 children had relatively large heads, and a few were somewhat clumsy in their gait.