Consequently, diagnostic delays between 10 and 20 years from symptom onset have been reported, 3,4 and an estimated 50% of narcolepsy cases remain undiagnosed. Comorbid diseases and medications that increase daytime sleepiness also add to the diagnostic challenges. The differential diagnosis of NT1 and NT2 can be particularly challenging because other conditions with similar symptomology of excessive daytime sleepiness, including Kleine-Levin syndrome and idiopathic hypersomnia, can be confused with narcolepsy. 11 The diagnosis of NT2 is more challenging due to the nonspecificity of symptoms, limitations of diagnostic tests, and the absence of useful biomarkers. 10 Currently, few clinical practices offer hypocretin testing, although testing for orexin-A/hypocretin-1 in spinal fluid is available through Mayo Clinic Laboratories.
8 Effective treatment is critical to the management of this condition, starting with a prompt differential diagnosis, which often requires assessment at specialized sleep centers. The associated significant health care resource utilization, the detrimental effect on employment, and stigma negatively affect the quality of life of individuals with narcolepsy.
Narcolepsy also increases the risk for serious accidents and injuries. The negative consequences of narcolepsy with or without cataplexy can be seen in various settings, including at schools, workplaces, and social settings. New treatment options have emerged from improved understanding of the underlying pathophysiologic mechanisms of narcolepsy, with treatments targeting the histamine 3 receptor and dopamine and norepinephrine reuptake recently being approved. In contrast, for other patients their narcolepsy may become refractory to treatment or treatment may be contraindicated due to comorbidities or the use of concomitant medications. 3 However, despite their efficacy, conventional treatments that have been used as the standard of care for excessive daytime sleepiness (modafinil, armodafinil, stimulants, and sodium oxybate) and cataplexy (sodium oxybate and venlafaxine) may not be tolerated by some patients. Because there is no cure for this condition, current treatments aim to improve wakefulness and reduce cataplexy attacks, sleep disruption, sleep paralysis, and sleep-related hallucinations. Narcolepsy, with or without cataplexy, can have a substantial detrimental effect on well-being and quality of life. 6 A health care claims database that includes 6703 individuals diagnosed with narcolepsy with and without cataplexy estimates an overall prevalence of 79.4 per 100,000 - 65.4 per 100,000 without cataplexy and 14.0 per 100,000 with cataplexy - with the prevalence increasing with age (Figure). 4 The prevalence estimates range from 20 to 67 people per 100,000 5 to as many as 180 per 100,000. 3 However, the exact prevalence of this condition is challenging to determine due to underdiagnosis and delayed diagnosis. 1,2Ī relatively rare condition, narcolepsy affects children and adults of both sexes. 1 NT2 presents with the same characteristics as NT1 but excludes cataplexy however, cataplexy has been later observed in people initially diagnosed with NT2, resulting in its re-diagnosis as NT1. NT1 is associated with the symptom of cataplexy, the sudden loss of muscle tone, which is estimated to affect up to 60% of patients with narcolepsy. The International Classification of Sleep Disorders-Third Edition recognizes 2 types of narcolepsy: narcolepsy type 1 (NT1) and type 2 (NT2). Narcolepsy is a chronic sleep disorder characterized by severe and persistent daytime sleepiness.
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