Sleep disorder testing performed during the acute phase of an illness or injury is not appropriate.
Narcolepsy. — Narcolepsy is a neurologic disorder of unknown etiology characterized predominantly by abnormalities of REM, some abnormalities of NREM sleep and the presence of excessive daytime sleepiness often with involuntary daytime sleep episodes. Other associated symptoms of narcolepsy include cataplexy and other REM sleep phenomena, such as sleep paralysis and hypnogogic hallucinations.
Related diagnostic testing is covered if the patient has inappropriate sleep episodes or attacks (e.g., while driving, in the middle of a meal, in the middle of a conversation), amnesiac episodes or continuous disabling drowsiness. The sleep disorder clinic must maintain documentation that this condition is severe enough to interfere with the patient’s well-being and health.
The diagnosis of narcolepsy is usually confirmed by overnight polysomnography followed by a multiple sleep latency test (MSLT) the next day. The following measurements are normally required to diagnose narcolepsy:
- PSG assessment of the quality and quantity of night-time sleep;
- Mean sleep latency of 8 minutes or less for 4 or more naps in the MSLT; and
- The presence of two or more sleep-onset REM periods during the MSLT.
Repeat polysomnography may be indicated if the initial PSG and MSLT fail to identify narcolespy when:
- The first study is technically inadequate due to equipment failure;
- The patient could not sleep or slept for a insufficient amount of time to determine a clinical diagnosis;
- The initiation of therapy or confirmation of the efficacy of prescribed therapy is clinically needed; or
- The results were inconclusive.