Atypical Kleine Levin Syndrome: Atypical or “Something Else”

Abstract

Objective: To describe in some detail published cases who were diagnosed as atypical Kleine-Levin syndrome (KLS), and discuss the validity and usefulness of this diagnostic term. Methods: The English written literature was reviewed using the search terms Atypical KLS, KLS mimic, KLS like and KLS variant. Only reports which provided complete clinical features were reviewed. The present diagnostic criteria of KLS were applied in each case and the reasons why each case was considered as atypical were outlined in a table form. The cases were grouped according to the primary etiologies which could explain the symptoms into infectious, autoimmune, cerebrovascular, head trauma, brain tumor and genetic metabolic disorders. Cases in whom we could not establish a definite diagnosis were coined “atypical “and a few which could not be assigned to a specific group were coined “miscellaneous”. Results: Fifty seven reports describing 60 “atypical“ cases were found. Out of those, 14 suffered from a variety of medical conditions which could explain the symptomology while in 19 cases a definite diagnosis could not reached. Five cases were coined as “miscellaneous” since we could not assign them to a specific group. Conclusion: The eponym “atypical” KLS, refers to patients in whom a variety of medical disorders were associated with sleep-wake disorder, however, it seems appropriate that in such cases the diagnosis should express the primary cause of the symptoms rather than suggesting that those cases are a variant of KLS.