The utility of a 5(th) nap in multiple sleep latency test

Multiple Sleep Latency Test: when are 4 naps enough?

STUDY OBJECTIVES

The Multiple Sleep Latency Test (MSLT) is central to the diagnosis of narcolepsy and idiopathic hypersomnia. This study is the first to assess the impact of a 5-nap protocol on meeting MSLT-derived diagnostic criteria in a general cohort referred for MSLT, without selection bias.

METHODS

Data for all MSLTs performed at 2 tertiary sleep units in Australia between May 2012 and May 2018 were retrospectively assessed for the impact of the fifth nap on mean sleep latency (MSL) and sleep onset rapid eye movement periods.

RESULTS

There were 122 MSLTs included. The MSL was 8.7 ± 5.1 minutes after 4 naps, compared with 9.2 ± 5.2 minutes for 5 naps (P < .0001). In 8 cases, inclusion of the fifth nap changed the MSL to a value above the diagnostic threshold of 8 minutes. There were no instances in which the MSL moved to ≤ 8 minutes based on fifth nap data. A sleep onset rapid eye movement period occurred in the fifth nap in 9 patients and altered the interpretation in 2 cases.

CONCLUSIONS

The fifth nap in an MSLT is associated with an increased MSL, although this difference is rarely clinically significant. In patients with borderline MSL or 1 sleep onset rapid eye movement period after 4 naps, a fifth nap can alter the outcome and should be performed. However, for many cases, a 4-nap MSLT protocol will suffice, potentially allowing resource savings without compromising diagnostic accuracy. We propose the adoption of a conditional 4-nap or 5-nap protocol based on specific criteria.

A Case of Off-label Sodium Oxybate in an 11-Year-Old with Narcolepsy

Narcolepsy is a rare chronic condition which affects sleep architecture. It may manifest in childhood or adolescence by causing excessive daytime sleepiness, sleep attacks, and hallucinations. Research suggests that there is a significant delay in diagnosis with the mean age being 10 to 15 years from onset of symptoms. Although narcolepsy is predominantly associated with loss of hypocretin (orexin), the role of genetics is complementary to the diagnosis. In addition, clinical manifestations of symptoms vary in presentation and severity from case to case. Therefore, this report provides an opportunity to review pediatric narcolepsy including the diagnostic workup and clinical response to sodium oxybate. This particular case describes an 11-year-old boy meeting the clinical and diagnostic criteria for narcolepsy. Clinically, the patient had a very positive response to treatment with sodium oxybate, which at the time of initiating therapy was off-label for patients under the age of 18.

Off-label Sodium Oxybate in Childhood Narcolepsy: A Comprehensive Report

Narcolepsy is a sleep disorder that can manifest in childhood or adolescence by causing excessive sleepiness, hallucinations, sleep attacks, or cataplexy. There is often a significant delay in diagnosis with the mean time being 15 years from the onset of symptoms, which may lead to further exacerbations and a high comorbidity burden. Although narcolepsy is predominantly associated with loss of hypocretin (orexin), the role of genetics is poorly understood and, therefore, is complementary to the diagnosis but not confirmatory. We present the case of a child who was misdiagnosed as suffering from schizophrenia only to later uncover narcolepsy with cataplexy. Even though she did not meet strict criteria for narcolepsy type 1, her history and objective data were consistent enough to make an official diagnosis. In addition, her clinical response to treatment was very positive, further supporting narcolepsy as the most likely underlying condition. This presentation highlights the importance of continued education and research to reduce the risk of delay in diagnosis or misdiagnosis.