The word
essential is sometimes
synonymous with
idiopathic (as in
essential hypertension,
essential thrombocythemia, and
essential tremor) and the same is true of
primary (as in
primary biliary cholangitis, or
primary amenorrhea), with the latter term being used in such cases to contrast with
secondary in the sense of "secondary to [i.e., caused by] some other condition." Another, less common synonym is
agnogenic (
agno-, "unknown" +
-gen, "cause" +
-ic). The word
cryptogenic (
crypto-, "hidden" +
-gen, "cause" +
-ic) has a
sense that is synonymous with
idiopathic and a sense that is contradistinguished from it. Some disease classifications prefer the use of the synonymous term
cryptogenic disease as in
cryptogenic stroke, and cryptogenic
epilepsy. The use of cryptogenic is also sometimes reserved for cases where it is presumed that the cause is simple and will be found in the future. Some
congenital conditions are idiopathic, and sometimes the word
congenital is used synonymously with
idiopathic; but careful usage prefers to reserve the word
congenital for conditions to which the literal sense of the word applies (that is, those whose pathophysiology has existed since the
neonatal period). ==Syndrome without a name==