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, after obstructive sleep apnea has been ruled out by polysomnography; or
   2. For members with clinical features of sleep apnea (obstructive or central), to provide an objective assessment of sleepiness.

   Aetna considers MSLT experimental and investigational for all other indications (e.g., evaluation of the effectiveness of modafinil therapy in narcolepsy) because its effectiveness for indications other than the ones listed above has not been established.

   According to the American Sleep Disorders (AASM) Standards of Practice Committee, MSLT alone is not sufficient for the diagnosis of sleep apnea; polysomnography is necessary to establish this diagnosis.  Although the results of the MSLT alone do not establish the diagnosis of sleep apnea, the MSLT may be medically necessary to quantify the magnitude of excessive sleepiness in sleep apnea syndromes.

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

   1. The first test was invalid or uninterpretable; or
   2. The response to treatment needs to be ascertained; or
   3. The member is suspected of having more than 1 sleep disorder (such as when a member diagnosed with sleep apnea continues to suffer from excessive daytime sleepiness despite treatment with continuous positive airway pressure); or
   4. If results of previous testing are remote (most recent prior MSLT test was conducted 2 or more years ago).

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 guidelines from the AASM (Littner et al, 2001), for patients suspected of having narcolepsy, an all-night polysomnogram is done primarily to ascertain the presence of concurrent sleep disorders and is followed immediately by a MSLT to help confirm the diagnosis.  The MSLT also helps determine the severity of daytime sleepiness.  AASM guidelines (2000) stated that the MSLT is not routinely indicated for the evaluation of insomnia.

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.