Objectives

The patho-aetiology of narcolepsy Type I (NT1) is the loss of hypocretin-1 secreting neurons in the hypothalamus. Diagnostic criteria for NT1 include excessive daytime sleepiness (EDS) for at least three months not explained by any other condition, cataplexy and cerebrospinal fluid (CSF) hypocretin-1 concentrations lower than 110 pg/ml. In this study we evaluated the utility of measuring CSF hypocretin-1 levels in patients with suspected narcolepsy (N).

Methods

The study included 29 consecutively recruited patients at a tertiary sleep centre presenting with EDS for exclusion of N. All patients were examined using an extensive clinical interview followed by two weeks of actigraphy and sleep diary recordings, polysomnography (PSG) and multiple sleep latency testing (MSLT). Additionally, HLA-typing, urinary screening for substances of abuse and a lumbar puncture to measure CSF hypocretin-1 expression using radioimmunoassay were carried out.

Results

In sum, 19 patients (66%) had a CSF hypocretin-1 level <110 pg/ml, of whom two had current severe depression without any features of narcolepsy except EDS. The predictive potential of hypocretin-1 measurement in diagnosing narcolepsy revealed a positive predictive value (PPV) of 89%, a specificity of 83%, with both negative predictive value (NPV) and sensitivity equal to 100%.

Conclusions

Despite a high sensitivity and specificity, the MSLT is not always a reliable diagnostic test for narcolepsy and where this uncertainty exits, CSF hypocretin-1 concentrations <110 pg/ml can be useful. However, due to a lower PPV and specificity at this cut-off, it may also not be entirely reliable as a stand-alone diagnostic test, particularly in the context of severe depression.

中文翻译：

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在怀疑有发作性睡病的患者中测量CSF hypocretin-1水平的实用性。

目标

I型发作性睡病（NT1）的病理病因是下丘脑中分泌分泌hycrecretin-1的神经元的丢失。NT1的诊断标准包括至少三个月的白天过度嗜睡（EDS），没有其他任何情况可以解释，脑瘫和脑脊液（CSF）hypocretin-1浓度低于110 pg / ml。在这项研究中，我们评估了在怀疑有发作性睡病（N）的患者中测量CSF hypocretin-1水平的实用性。

方法

该研究纳入了29名在三级睡眠中心连续入选的EDS排除N的患者。所有患者均接受了广泛的临床访谈，随后进行了两周的眼动描记和睡眠日记记录，多导睡眠图（PSG）以及多次睡眠潜伏期测试（ MSLT）。此外，还进行了HLA分型，尿液中滥用物质的筛查以及腰椎穿刺以使用放射免疫测定法测量CSF hypocretin-1的表达。

结果

总之，有19名患者（66％）的CSF hypocretin-1水平<110 pg / ml，其中2例目前严重抑郁，除EDS以外没有发作性睡病的任何特征。hypocretin-1检测在发作性睡病诊断中的预测潜力显示阳性预测值（PPV）为89％，特异性为83％，阴性预测值（NPV）和敏感性均等于100％。

结论

尽管敏感性和特异性高，但MSLT并非始终是针对发作性睡病的可靠诊断测试，并且在存在不确定性的情况下，脑脊液hypercretin-1浓度<110 pg / ml可能有用。但是，由于该临界值下的PPV和特异性较低，因此作为独立的诊断测试，也可能并不完全可靠，尤其是在严重抑郁的情况下。