Kraepelin (10) in 1908 first defined a group within his classification of schizophrenia which he described as periodic catatonia. The clinical features of this type may be briefly summarized. The onset, usually between 14 and 20 years, is frequently characterized by a period of erratic conduct followed by an interval of stupor, confusion or excitement, which thereafter undergoes periodic remissions and relapses. The periodicity is remarkable in the rapidity with which all changes occur. In the periods of remission the patient is free of catatonia and associated symptom-complex (sympatheticotonia), but is still dull, apathetic and withdrawn; he often recalls events from the reactive phase, but without insight. The patient is still schizophrenic, with emotional flattening and poverty of ideation, and remains so throughout. In the reactive phase the picture is one of catatonic stupor or excitement, with clinical evidence of sympathetic over-activity.