Kleine-Levin syndrome; An update and mini-review.

Since 1962, when Critchley and Hoffman coined the term Kleine-Levin Syndrome (KLS) for the triad of hypersomnia, excessive eating and "often abnormal behavior" which they have observed in 11 adolescent boys, the number of patients recognized with this rare syndrome expanded, the spectrum of the clinical presentation, disease course, prognosis, gender specificity and the presence of familial cases were established. However, in spite of the progress made in neuroscience, the search for the cause, neuroanatomy, pathophysiology and drug treatment of KLS is still ongoing. In this mini-review we will describe in some detail the scientific efforts made to understand in depth the complex symptomatology of KLS and refer also to updated findings reached up till now.