Frontal intermittent rhythmic delta activity (FIRDA), rhythmic slow wave pattern lasting several seconds over the anterior leads of electroencephalography (EEG), has been reported in a wide variety of clinical conditions. We investigated the clinical significance of FIRDA without structural brain lesions. We reviewed 7689 EEGs between October 2017 and September 2019 at a university hospital. Patients (age >18 years) who were confirmed to have “nonsignificant neuroimaging” were examined. Clinical data were retrospectively collected, and the estimated cause was carefully decided. We found 83 FIRDA among 7689 EEGs (1.08%). After patients with any structural lesion identified on neuroimaging were excluded, 37 FIRDAs were reviewed. There were 20 (51.35%) patients of metabolic encephalopathy. Six patients showed FIRDA due to neurodegenerative disease (16.21%). In addition, we found 6 (16.21%) of neurodegenerative disease and 5 (13.51%) of hypoxic encephalopathy (cardiac arrest). Four (16.21%) patients were related to systemic infection (10.81%), whereas 2 were related to encephalitis (5.40%). We demonstrated several potential etiologies, including metabolic encephalopathy, neurodegenerative disease, hypoxic encephalopathy, and infections, which should be considered in the case of FIRDA without structural brain lesions.

中文翻译：

---

无结构性脑损伤的额叶间歇性节律性 Delta 活动的临床相关性

额叶间歇性节律性 delta 活动 (FIRDA)、节律性慢波模式在脑电图 (EEG) 的前导联上持续数秒，已在各种临床情况中得到报道。我们研究了没有结构性脑损伤的 FIRDA 的临床意义。我们回顾了 2017 年 10 月至 2019 年 9 月期间在大学医院的 7689 份脑电图。检查了被确认具有“无显着神经影像学”的患者（年龄 >18 岁）。回顾性收集临床数据，并仔细确定估计的原因。我们在 7689 个脑电图中发现了 83 个 FIRDA（1.08%）。在排除神经影像学发现的任何结构性病变的患者后，审查了 37 份 FIRDA。代谢性脑病患者20例（51.35%）。6 名患者因神经退行性疾病而出现 FIRDA（16.21%）。此外，我们发现了 6 例 (16.21%) 神经退行性疾病和 5 例 (13.51%) 缺氧性脑病（心脏骤停）。4 名（16.21%）患者与全身感染有关（10.81%），而 2 名患者与脑炎有关（5.40%）。我们证明了几种潜在的病因，包括代谢性脑病、神经退行性疾病、缺氧性脑病和感染，在没有结构性脑损伤的 FIRDA 的情况下应该考虑这些病因。