1. Aetna considers the multiple sleep latency test (MSLT) medically necessary for either of the following 2 indications:

   1. For evaluation of symptoms of narcolepsy, to confirm the diagnosis; or
   2. For evaluation of persons with suspected idiopathic hypersomnia to help differentiate idiopathic hypersomnia from narcolepsy.

   Aetna considers MSLT experimental and investigational for all other indications because its effectiveness for indications other than the ones listed above have not been established, including (not an all-inclusive list): chronic fatigue syndrome; circadian rhythm disorders; insomnia, neurologic disorders other than narcolepsy; obstructive sleep apnea syndrome; and evaluation of the effectiveness of modafinil therapy in narcolepsy.

2. Aetna considers repeat MSLT tests not medically necessary, unless:

   1. The initial test was invalid or uninterpretable; or
   2. The initial test is affected by extraneous circumstances or when study conditions were not present during initial testing; or
   3. The patient is suspected to have narcolepsy but earlier MSLT evaluation did not provide polygraphic confirmation.
       

3. Aetna considers single nap studies experimental and investigational because a full MSLT is required for accurate diagnosis of narcolepsy.

4. Aetna considers home MSLT experimental and investigational because home MSLT has not been proven to be equivalent to formal MSLT performed in a sleep laboratory.

See also CPB 0004 - Obstructive Sleep Apnea in Adults.

The multiple sleep latency test (MSLT) involves multiple trials during a day to objectively assess sleep tendency by measuring the number of minutes it takes the patient to fall asleep.  The patient may be instructed to lie down in a dark room, with permission or a suggestion given to sleep (MSLT) or to sit up in a dimly lit room and try to stay awake (maintenance of wakefulness test).  The MSLT is the better test for demonstration of sleep-onset rapid eye movement (REM) periods, a determination that is important in establishing the diagnosis of narcolepsy.  Parameters necessary for sleep staging (including 1 to 4 channels of EEG, EOG, and chin EMG) are recorded. 

According to AASM guidelines (Littner, et al., 2005), the MSLT is indicated as part of the evaluation of patients with suspected narcolepsy to confirm the diagnosis. The MSLT may be indicated as part of the evaluation of patients with suspected idiopathic hypersomnia to help differentiate idiopathic hypersomnia from narcolepsy. The MSLT is not routinely indicated in the initial evaluation and diagnosis of obstructive sleep apnea syndrome or in assessment of change following treatment with nasal CPAP (Littner, et al., 2005). The MSLT is not routinely indicated for evaluation of sleepiness in medical and neurological disorders (other than narcolepsy), insomnia, or circadian rhythm disorders. According to the AASM (Littner, et al., 2005), repeat MSLT testing may be indicated in the following situations: (a) when the initial test is affected by extraneous circumstances or when appropriate study conditions were not present during initial testing, (b) when ambiguous or uninterpretable findings are present, (c) when the patient is suspected to have narcolepsy but earlier MSLT evaluation(s) did not provide polygraphic confirmation.

Huang et al (2008) noted that the cause and pathogenesis of Kleine-Levin syndrome, a recurrent hypersomnia affecting mainly male adolescents, remain unknown, with only scant information on the sleep characteristics during episodes.  These investigators described findings obtained with polysomnography (PSG) and MSLT and correlation obtained between clinical and PSG findings from different episodes.  A total of 19 patients (17 males) were investigated with PSG and MSLT; 10 had data during both symptomatic episode and asymptomatic interval.  The analyses considered day of onset of symptoms and relationship between this time of onset and day of recording during the symptomatic period.  When PSG was performed early (before the end of the first half of the symptomatic period), an important reduction in slow wave sleep (SWS) was always present with progressive return to normal during the second half (with percentages very similar to those monitored during the asymptomatic period) despite persistence of clinical symptoms.  Rapid eye movement sleep remained normal in the first half of the episode but decreased in the second half: the differences between first and second half of episodes were significant for SWS (p = 0.014) and REM sleep (p = 0.027).  The overall mean sleep latency at MSLT was 9.51 +/- 4.82 mins and 7 of 17 patients had 2 or more sleep onset REM periods during the symptomatic period.  The authors concluded that important changes in sleep occur over time during the symptomatic period, with clear impairment of SWS at symptom onset.  However, MSLT is of little help in defining sleep problems and findings from the MSLT do not correlate with symptom onset.

Yeh and Schenck (2010) compared MSLT and Epworth sleepiness scale (ESS) for evaluating the effectiveness of modafinil in treating excessive daytime sleepiness in patients with narcolepsy.  A total of 10 consecutive patients with narcolepsy-with-cataplexy who were treated with 200 mg/day modafinil for more than 6 months were included in this study.  This comparative study was prompted by the requirement of the Bureau of National Health Insurance in Taiwan that modafinil users need to be followed-up with MSLTs every 6 to 12 months.  The mean age at onset of narcolepsy onset in these 10 patients was 11.8 +/- 3.3 years, and 8 (80 %) were male.  These investigators compared the differences in MSLT and ESS between baseline and follow-up at 6 to 12 months after starting modafinil therapy using paired-t tests.  Epworth Sleepiness Scale scores (p < 0.001) were considerably more sensitive than MSLT scores (p < 0.05) in documenting the effectiveness of modafinil and that improvements in MSLT scores were minimal and remained in the pathologically sleepy range.  These findings suggested that the ESS is a more sensitive and clinically meaningful tool to evaluate the effectiveness of modafinil in narcolepsy.

Mariman et al (2013) evaluated undiagnosed and co-morbid disorders in patients referred to a tertiary care center with a presumed diagnosis of chronic fatigue syndrome (CFS).  Patients referred for chronic unexplained fatigue entered an integrated diagnostic pathway, including internal medicine assessment, psychodiagnostic screening, physiotherapeutic assessment and PSG + MSLT.  Final diagnosis resulted from a multi-disciplinary team discussion.  Fukuda criteria were used for the diagnosis of CFS, DSM-IV-TR criteria for psychiatric disorders, ICSD-2 criteria for sleep disorders.  Out of 377 patients referred, 279 (74.0 %) were included in the study [84.9 % female; mean age of 38.8years (SD 10.3)].  A diagnosis of unequivocal CFS was made in 23.3 %.  In 21.1 %, CFS was associated with a sleep disorder and/or psychiatric disorder, not invalidating the diagnosis of CFS.  A predominant sleep disorder was found in 9.7 %, 19.0 % had a psychiatric disorder and 20.8 % a combination of both.  Only 2.2 % was diagnosed with a classical internal disease.  In the total sample, a sleep disorder was found in 49.8 %, especially obstructive sleep apnea syndrome, followed by psychophysiologic insomnia and periodic limb movement disorder.  A psychiatric disorder was diagnosed in 45.2 %; mostly mood and anxiety disorder.  The authors concluded that a multi-disciplinary approach to presumed CFS yielded unequivocal CFS in only a minority of patients, and revealed a broad spectrum of exclusionary or co-morbid conditions within the domains of sleep medicine and psychiatry.

However, an UpToDate review on “Clinical features and diagnosis of chronic fatigue syndrome” (Gluckman, 2014) does not mention the use of MSLT as a diagnostic tool.