Complex sentence: The syndrome appeared in sporadic as well as epidemic cases and in 1969, benign myalgic encephalomyelitis appeared as an antry to the International Classification of Diseases under Diseases of the nervous system.
Split into simpler sentences: The syndrome appeared in sporadic as well as epidemic cases. In 1969, benign myalgic encephalomyelitis was first classified into the International Classification of Diseases under Diseases of the nervous system.