Complex sentence: Cases of MS before the CIS are sometimes found during other neurological inspections and are referred to as subclinical MS. Preclinical MS refers to cases after the CIS but before the confirming second attack.
Split into simpler sentences: Cases of MS before the CIS are sometimes found during other neurological inspections and are referred to as "subclinical MS". "Preclinical MS" refers to cases after the CIS but before the confirming second attack.