Exegesis:

kai hoi enochloumenoi apo pneumatōn akathartōn etherapeuonto ‘and those who were troubled with unclean spirits were healed,’ mentioning a special category among those that had come to be cured. apo pneumatōn akathartōn goes with enochloumenoi and indicates the cause or the source of their being troubled (apo = hupo.

enochleomai, passive ‘to be troubled,’ ‘to be plagued.’

Translation:

One should take care not to suggest a contrast between those who “came … to be healed” (v. 17) and those who actually “were cured” (here): vv. 18f intend to show that, and how, the people who came were healed.

Trouble with unclean spirits refers to demon possession (see on 4.33); for unclean spirit see on 4.36. For cured see on “heal” in 4.23.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.