2 International Classification of Diseases (ICD‐10) [3]
3 Diagnostic and Statistical Manual of Mental Disorders (DSM) [4]
4 International Classification of Sleep Disorders, Third Edition (ICSD‐3) [1]
For the sake of clarity and simplicity, the ICSD‐3 will be the primary focus for the classification of sleep disorders that the dentist, especially when involved in the care and management of patients with a sleep‐related breathing disorder (SRBD), will most commonly encounter and utilize. It must be kept in mind that the recognition of a sleep disorder does not mean that the dentist is making the diagnosis. The intent here is that by recognizing that a sleep disorder may be present the dentist is establishing the risk for such a disorder and by doing so can then make the appropriate referral for a more definitive diagnosis and subsequent treatment as is deemed necessary.
Diagnostic Classification of Sleep and Arousal Disorders (DCSAD)
The DCSAD was the first classification system for defining sleep disorders. It was first published in 1979. The DCSAD was subsequently used as the foundation for the formation of the other future classification systems, in particular the ICSD that was first published in 1990 [2]. The DCSAD was structured such that it organized the sleep disorders into symptomatic categories and thus became the basis of the more current classification system used today. This classification system was first published by the Association of Sleep Disorders Centers, founded in 1975, then became known as the American Sleep Disorders Association (ASDA), and today it is known as the American Academy of Sleep Medicine (AASM).
International Classification of Disease (ICD‐10)
In 1948, the World Health Organization (WHO), which is part of the United Nations System, was formed and it published the sixth edition of the ICD [5] for the purposes of diagnostic coding as well as collating mortality statistics regarding all medical conditions. The initial development of the ICD‐10 started in 1983 and was approved by the WHO in 1990. The World Health Organization is the organization that publishes the ICD; however, member countries, like the United States, are authorized to make appropriate modifications for clinical purposes as well as for heath management. The ICD has since undergone multiple revisions that include clinical modifications (CM) resulting in the ICD‐10‐CM [3]. In the Introduction to the ICSD‐3 under the coding section, it is reported that the codes that defined the various classifications in the ICSD were not always found to be in agreement with the ICD codes.
At this time the majority of the sleep disorders are the G47 codes and these are in the chapter Diseases of the Nervous System. This group of codes applies to many of the more commonly encountered sleep disorders and will be reviewed more specifically, especially those that are of importance to the dentist, as each of the sleep disorders is reviewed in this chapter. The codes that begin with R06 are related to abnormal breathing, such as snoring and even mouth breathing. These are respiratory codes that are associated with abnormal clinical and laboratory findings as well as signs and symptoms that are not otherwise classified. The F50 codes are in the broad category of behavioral disorders. In this specific group, these are sleep disorders (F51) that are not related to a substance or to any known physiological condition.
In January of 2022 the ICD‐11 will go into effect. Information regarding this can be found on the website for the WHO. As in the past this may undergo some adaptive revisions to conform to the healthcare system in the United States.
Diagnostic and Statistical Manual of Mental Disorders (DSM)
This category of coding is focused on psychiatric and mental health issues. It is currently referred to the DSM‐5 and was published in May of 2013 [4]. The ICSD‐3 was used as a guide for the incorporation of diagnostic coding in this publication. The primary focus has been and is on insomnia; however, in the DSM‐5 attention was given to other sleep disorders under the broad category of sleep–wake disorders. This included 10 diagnostic groups that included other sleep disorders such as sleep apnea, narcolepsy, rapid eye movement (REM) behavior disorders, and circadian rhythm disorder to name a few. The overall importance of this is based on the growing evidence that sleep disorders may coexist with a variety of medical and psychiatric conditions and these may interact and impact one another.
The International Classification of Sleep Disorders (ICSD)
In 1990, the ICSD was first published as a joint effort between the ASDA, European Sleep Research Society, the Japanese Society of Sleep Research, and the Latin American Sleep Society [6]. It was developed mainly for diagnostic, epidemiologic, and research purposes. It was intended to enhance communication relative to sleep disorder research for the international community.
Since the pathophysiology of many of these sleep disorders was not well understood at that time, the ICSD was based on the most common or major symptoms. These consisted primarily of insomnia, excessive sleepiness, and parasomnias (abnormal events that would take place while sleeping).
In 2005, the second edition of the ICSD was published and this made minor changes and updates to the original ICSD. As more research on the various sleep disorders was being published, the need to further revise and update the classifications to be more relevant became evident. In 2011, the need to have a classification system that was based as much as possible on the most current evidence available was initiated that resulted in the third edition. The third edition was basically similar in structure to the second edition as it relates to various clinical categories. In addition an effort was made to coordinate the ICD‐10‐CM codes where possible. This was not always practical because there was no total agreement between the ICD coding and the coding of sleep disorders based on the criteria established in the third edition.
The third edition of the ICSD has a large number of sleep disorders that are of little to no consequence to the practicing dentist. The intent therefore is to be aware of the various categories of those disorders, and attention will be given to those that are most important and are most relevant. If there is interest in reviewing all of the sleep disorders in more detail, it is advisable that the ICSD‐3 be obtained from the AASM. This would provide more detail(s) regarding all of the sleep disorders and in addition would be educational. Each of the sleep disorders is accompanied by discussion as well as a bibliography of evidence that supports the diagnosis as being clinically relevant. The third edition was the outcome of a task force that oversaw the development of this project, and in addition there were specific workgroups made up of experts related to the respective categories.
General Categories
The ICSD‐3 contains six general categories of sleep disorders, and under each of these are more detailed and descriptive disorders. In each of these categories there is a description of alternate names that may apply or may be used as well the specific diagnostic criteria that need to be met to make each diagnosis. In most instances the essential features of the disorder are reviewed. In addition to the six general categories there are three additional categories: Other Sleep Disorder, Appendix A, and Appendix B. The presence of the ICD‐10‐CM code in association with each disorder, when present, is specific to that disorder based on the relevant criteria.
The six general categories of sleep disorders are as follows:
Insomnia
Sleep‐related breathing disorders
Central disorders of hypersomnolence
Circadian rhythm sleep–wake disorders
Parasomnias
Sleep‐related movement disorders