4. For the purposes of section 3, a civil servant is physically or mentally disabled if he suffers from a serious, prolonged pathological condition.
A pathological condition is serious if it makes the civil servant totally incapable of performing the work required by the position he occupied for an extended period of time.
A pathological condition is prolonged if it is to last indefinitely, that is, if it is unlikely that a cure is possible in the present state of medical knowledge.