OBJECTIVE Nerve conduction studies (NCS) are essential to differentiate between demyelinating and axonal subtypes in Guillain-Barré syndrome (GBS). However, it is debated to which extent the delay of NCS after symptom onset and repeated measurements during the disease course influence the diagnostic accuracy. METHODS We evaluated NCS in 93 patients with a classical GBS applying two widely used criteria (Hadden's and Rajabally's). The initial measurements after symptom onset were compared to follow-up studies where available (n = 43). We analyzed the influence of NCS timing after symptom onset and clinical severity on fulfilling the electrophysiological criteria for axonal or demyelinating subtypes and evaluated the impact of repeated measurements. We further evaluated the presence of reversible conduction failure. RESULTS A higher GBS disability scale at nadir correlated with a successful subclassification whereas the delay of the first NCS after symptom onset did not influence the diagnostic yield (75% for Hadden's and 68% for Rajabally's criteria for the first assessment). A second measurement allowed the additional successful classification in 19% and 14% of patients, respectively. On the other hand, a repeated measurement in patients with an initial successful classification resulted in a different subtype in 5% and 7%, respectively. Reversible conduction failure was found in 7% of patients. CONCLUSION Clinical severity but not timing of NCS influenced the fulfilment of electrophysiological criteria for either the axonal or demyelinating subtype. Repeated electrophysiological measurements led to a further specification or a change in subtype classification in a relevant proportion of patients.

中文翻译：

---

吉兰-巴雷综合征的神经传导研究：时间和重复测量值的影响

目的 神经传导研究 (NCS) 对区分吉兰-巴雷综合征 (GBS) 的脱髓鞘亚型和轴突亚型至关重要。然而，在症状出现后延迟 NCS 并在病程中重复测量会在多大程度上影响诊断准确性存在争议。方法 我们应用两种广泛使用的标准（Hadden 和 Rajabally）评估了 93 名经典 GBS 患者的 NCS。症状出现后的初始测量值与可用的后续研究进行比较（n = 43）。我们分析了症状出现后 NCS 时间和临床严重程度对满足轴突或脱髓鞘亚型的电生理标准的影响，并评估了重复测量的影响。我们进一步评估了可逆传导失败的存在。结果 最低点的较高 GBS 残疾量表与成功的子分类相关，而症状出现后第一次 NCS 的延迟不影响诊断率（Hadden's 为 75%，Rajabally 的第一次评估标准为 68%）。第二次测量允许分别在 19% 和 14% 的患者中进行额外的成功分类。另一方面，对初始成功分类的患者进行重复测量，结果分别为 5% 和 7% 的不同亚型。在 7% 的患者中发现了可逆传导失败。结论 NCS 的临床严重程度而非时间影响了轴突或脱髓鞘亚型电生理标准的实现。