Narcolepsy: A clinical review

Tetrad of Narcolepsy Type 1: Treatment and Management

Narcolepsy is a chronic condition that brings about excessive daytime sleepiness. It can be classified into two types: narcolepsy type 1 (presence of cataplexy, which is marked by weakness of muscles) and narcolepsy type 2 (without cataplexy). It is generally underdiagnosed, which results in delayed diagnosis of the condition. It has more prevalence in the United States of America as compared to India. The narcoleptic tetrad consists of excessive daytime sleepiness (EDS), cataplexy, sleep paralysis, and hypnagogic hallucinations. Rapid eye movement (REM) sleep behavior disorder is another characteristic feature. Research about narcolepsy has been carried out for about 145-150 years, but it is only in the last 18-20 years that there has been advancement in the underlying pathophysiology, diagnosis, and, thus, availability of better treatment. Both pharmacological and non-pharmacological methods are preferred in treating narcolepsy, yet there is no cure for it. Since the knowledge regarding this condition is very limited, it is often misunderstood, and dealing with it is mentally and socially draining, often causing anxiety in the patients, feeling of social isolation, and other significant impacts on the quality of living. Raising awareness about narcolepsy is vital to prevent further medical attention delays.

Reliability and validity of the Japanese version of the Ullanlinna Narcolepsy Scale and Swiss Narcolepsy Scale for screening Japanese individuals with narcolepsy type 1

OBJECTIVE

To validate the Japanese versions of the Ullanlinna Narcolepsy Scale (J-UNS) and Swiss Narcolepsy Scale (J-SNS) for screening narcolepsy in the Japanese population and to discuss strategies for their use in hypersomniac individuals.

METHODS

We selected 451 outpatients with excessive daytime sleepiness (EDS) already diagnosed according to the International Classification of Sleep Disorders third edition. They responded to both scales twice at 1-month intervals. After eliminating individuals who met the exclusion criteria, validity and reliability analyses were performed on 408 and 381 participants, respectively.

RESULTS

Patients with narcolepsy type 1 (NT1) displayed higher J-UNS and lower J-SNS scores than those with NT2 and other sleep disorders. The intraclass correlation coefficients and weighted κ coefficient for scale scores in the total participants and patients with NT1 were ≥0.70 and ≥ 0.40, respectively, indicating high reliability. Furthermore, both the sensitivity and specificity of these scales upon using the original cut-off scores (14 for UNS and 0 for SNS) for detecting NT1 were 0.70 or ≥0.70, suggesting high validity. Additionally, the receiver operating characteristic curve analysis revealed that the best cut-off score did not change for the J-SNS but that for the J-UNS, it increased to 18. In our study, the scale's sensitivity and specificity changed from 96% to 82% and 58%-78%, respectively.

CONCLUSIONS

Both scales revealed satisfactory screening abilities for NT1 in the Japanese population. However, it may be better to use J-UNS cut-off scores of 18 for a population with EDS.

Treating Narcolepsy With Traditional Chinese Medicine

Narcolepsy is an uncommon brain condition characterized by falling asleep suddenly without any proper reason or time. In this chapter, the authors include a brief history of narcolepsy, clinical symptoms, pathophysiology, and current treatments for the disease. The review explains narcolepsy according to the theory of TCM. The authors review the curative effect, pharmacological properties, and clinical results of herbs and prescriptions against narcolepsy. The study searched keywords such as ‘narcolepsy,' ‘Traditional Chinese medicine,' ‘sleep disorder,' ‘excessive sleepiness,' and ‘medicinal treatment' using databases such as CNKI, PubMed, and Google Scholar. Based on the analysis of data obtained from 110 articles, the authors have classified the herbs and prescriptions by their curative effects, following the theory of traditional Chinese medicine. Some herbs can be used alone, while others can use in conjunction with other prescriptions.

Solriamfetol for the Use of Narcolepsy: A Systematic Review

Narcolepsy is a chronic and disabling neurological disorder characterized by excessive daytime sleepiness (EDS) and cataplexy. Historically, some medications have demonstrated efficacy in managing EDS and cataplexy symptoms. However, some patients cannot tolerate them, become refractory, or may use concomitant medications that preclude the use due to drug-drug interaction. Therefore, there is a necessity to explore the efficacy of new treatments, such as solriamfetol (JZP-110), a 2019 FDA-approved drug indicated to improve wakefulness in adults with EDS associated with narcolepsy. We conducted this systematic review to investigate the effectiveness of solriamfetol in EDS and cataplexy, and the drug's overall safety. For this study, we used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and MOOSE protocol. After an initial search of 119 papers, we included four clinical trials to investigate and analyze the use of solriamfetol for the treatment of narcolepsy. Solriamfetol was proven to improve objective measures of EDS in all clinical trials. We conducted this systematic review using objective measures such as the Epworth Sleepiness Scale and the Maintenance of Wakefulness Test. Overall, cataplexy was not formally evaluated in the four clinical trials; however, it demonstrated that EDS improved in patients with and without cataplexy. More clinical trials are needed to analyze the efficacy of solriamfetol on cataplexy. The effect of solriamfetol in EDS seems to be conclusive.

Alterations in the structural covariance network of the hypothalamus in patients with narcolepsy

PURPOSE

The hypothalamus plays a pivotal role in the pathogenesis of narcolepsy. This study aimed to evaluate the differences in the structural covariance network of thehypothalamus based on volume differences between patients with narcolepsy and healthy controls.

METHODS

We retrospectively enrolled 15 patients with narcolepsy and 19 healthy controls.All subjects underwent three-dimensional T1-weighted imaging using a 3-T magnetic resonance imaging scanner. Hypothalamic subunits were segmented, and the volumes of individual hypothalamic subunits were obtained using the FreeSurfer program. Subsequently, we conducted a structural covariance network analysis of the subunit volumes with graph theory using the BRAPH program in patients with narcolepsy and in healthy controls.

RESULTS

There were no significant differences in the volumes of the entire right and left hypothalamus nor in the hypothalamic subunit between patients with narcolepsy and healthy controls. However, we found significant differences in the structural covariance network in the hypothalamus between these groups. The characteristic path length was significantly lower in patients with narcolepsy than in healthy controls (1.698 vs. 2.831, p = 0.001). However, other network measures did not differ between patients with narcolepsy and healthy controls.

CONCLUSION

We found that the structural covariance network of the hypothalamus, as assessed from the subunit volumes of hypothalamic regions using a graph theoretical analysis, is different in patients with narcolepsy compared to healthy controls. These findings may contribute to the understanding of the pathogenesis of narcolepsy.