Diagnostic Criteria for Kleine-Levin Syndrome Expanded in Update to ICSD-3

The diagnostic criteria for Kleine-Levin Syndrome (KLS) were revised by the American Academy of Sleep Medicine (AASM) in updates to the organization’s International Classification of Sleep Disorders, third edition (ICSD-3). The new criteria, according to the Kleine-Levin Syndrome Foundation, will enable clinicians to recognize and diagnose cases of KLS more quickly and accurately. The updates are unlikely to affect previously diagnosed cases.

The changes in the updates to the ICSD-3 expand the diagnostic criteria of KLS. The updated text now lists derealization as a sign and symptom that occurs during KLS episodes, rather than the previously listed sign, altered perception. The updates also redefine hyperphagia as an example of a disinhibited behavior that may occur during an episode, instead of including a separate eating disorder criterion. Additionally, the criteria have expanded the list of indicators between episodes and now include normal or near-normal sleep and wakefulness, cognition, behavior, and mood. The updates broaden the definition of KLS to be more inclusive of cases that exhibit the core symptoms of the condition but do not meet the more narrowly defined criteria found in the previous version. The revisions are based on peer-reviewed, published research that was considered by a working group comprising the AASM board, sleep researchers, and medical doctors.

"KLS is a complex and rare neuropsychiatric disorder, the causes of which remain not fully understood. It is my sincere hope that the ICSD-3 improves diagnostic precision and accuracy, which will help advance research and clinical care in the disorder," said working group chair, Dr. David T. Plante.

KLS is a rare sleep disorder that predominantly affects adolescents. It causes extended periods of hypersomnia and cognitive and behavioral changes lasting from days to months. Onset typically occurs after a viral infection.