IRCCS Neuromed, Pozzilli (IS), Italy.
Department of Human Neuroscience, Sapienza University, Rome, Italy.
Pain. 2020 Oct;161(10):2385-2393. doi: 10.1097/j.pain.0000000000001920.
We aimed to investigate whether small-fibre pathology, a common skin biopsy finding in patients with fibromyalgia, implies clinically important abnormalities of somatosensory system function and verify whether it is associated with voltage-gated sodium channel variants. In 57 consecutively enrolled patients with fibromyalgia, we used skin biopsy to distinguish patients with and without small-fibre pathology. In all patients, we assessed somatosensory system function using quantitative sensory testing (QST) and laser-evoked potentials and investigated voltage-gated sodium channel genotyping. We then compared these variables in patients with and without small-fibre pathology. We found that clinical measures, QST, and laser-evoked potential variables did not differ between patients with and without small-fibre pathology. In most patients with small-fibre pathology, QST and laser-evoked potential variables fell within normative ranges commonly used in clinical practice. Of the 57 patients, one patient without small-fibre pathology and 2 patients with small-fibre pathology had rare variants of voltage-gated sodium channels, namely SCN11A, SCN9A, and SCN1A variants. The SCN9A variant, found in a patient with small-fibre pathology, was an already profiled gain-of-function mutation, previously reported in small-fibre neuropathy. Our findings suggest that small-fibre pathology has a negligible impact on somatosensory system function in fibromyalgia. The genetic analysis suggests that patients with rare small-fibre neuropathy due to voltage-gated sodium channel variants may be misdiagnosed as patients with fibromyalgia.
我们旨在研究小纤维病变（纤维肌痛患者常见的皮肤活检发现）是否意味着躯体感觉系统功能存在临床上重要的异常，并验证其是否与电压门控钠离子通道变体有关。在 57 名连续入组的纤维肌痛患者中，我们使用皮肤活检来区分有小纤维病变和无小纤维病变的患者。在所有患者中，我们使用定量感觉测试（QST）和激光诱发电位评估躯体感觉系统功能，并调查电压门控钠离子通道基因分型。然后，我们比较了有和无小纤维病变患者的这些变量。我们发现，有和无小纤维病变患者的临床指标、QST 和激光诱发电位变量没有差异。在大多数有小纤维病变的患者中，QST 和激光诱发电位变量均在临床实践中常用的正常范围内。在 57 名患者中，1 名无小纤维病变患者和 2 名有小纤维病变患者存在电压门控钠离子通道的罕见变体，即 SCN11A、SCN9A 和 SCN1A 变体。在有小纤维病变的患者中发现的 SCN9A 变体是一种已证实的功能获得性突变，先前在小纤维神经病中报道过。我们的研究结果表明，小纤维病变对纤维肌痛的躯体感觉系统功能影响可以忽略不计。基因分析表明，由于电压门控钠离子通道变体引起的罕见小纤维神经病患者可能被误诊为纤维肌痛患者。
