A Neurophysiological Investigation on the Genetic Factors for Febrile Convulsions

为了阐明热性惊厥（FC）和癫痫（EP）遗传因素之间的差异或联系，进行了两项研究；(1)对64例癫痫患者的113个后代进行前瞻性神经生理随访，这些患者被认为具有惊厥性疾病，特别是EP的高风险；(2)对88例fc患者的113个兄弟姐妹进行临床电研究。(1)在64例癫痫父母所生的103名儿童中，20名儿童出现临床癫痫发作（19.4%），27名儿童出现癫痫放电（26.2%）。在临床发作中，FC发作13例（12.6%），复发性发热性发作5例（4.9%），孤立性发热性发作（可能为良性婴儿惊厥）和创伤后早期发作各1例（1.0%）。根据Ohtahara的分类，FC病例又分为单纯性FC 4例（3.9%），复杂性FC 1例（1.0%），癫痫性FC 8例（7.8%）。在一般人群中儿童癫痫发病率较高，冈山县儿童癫痫发病率为0.82%。加上癫痫类FC，则上升到10倍以上。但是，与报道的一般人群FC患病率（5-10%）相比，单纯性FC（3.9%）或非癫痫性FC（4.9%）的发病率未见增加。2)对66例3岁以上癫痫父母的子代进行分析，在28例二级亲属内附加遗传因素（AGF）的病例中，临床癫痫发作的病例多达12例（42.9%）。这一比例显著高于38例无此类额外惊厥家族史的13.1%（5例）。虽然AGF组的FC发生率为28.6%（8例），非AGF组的FC发生率为10.5%（4例），但癫痫性FC在AGF组中占87.5%（7/8例），而在非AGF组中占25.0%（1/4例）。这些发现提示通过癫痫父母的遗传因素是癫痫易感性。3) 88例FC患儿113名兄弟姐妹中有39例（34.5%）发生FC，其中癫痫性FC 13例（11.5%）EEG表现为癫痫性放电。同样值得注意的是，单纯性FC的兄弟姐妹中未发现癫痫性FC。4)被认为是FC特征的伪小脉冲放电和睡眠发作性突波活动在单纯性FC中很少发现，而在癫痫性FC中却很常见。因此，这些脑电图模式，特别是后者，被认为与婴儿期和幼儿期的癫痫易感性有关。总之，这项调查支持抽搐和癫痫易感性之间的差异。癫痫性FC可能与病理性的癫痫易感性密切相关，而单纯性FC则是基于惊厥易感性的特定群体，对人类具有普遍的易感性，调节惊厥阈值。少

To clarify the difference or relation between genetic factors for febrile convulsions (FC) and epilepsy (EP), two studies were carried out ; (1)a prospective neurophysiological follow-up of cohort of 113 offspring of 64 epileptic patients supposed to have high risk for convulsive disorders, particularly for EP,and(2)a clinicoelectrical study on 113 sibling of 88 patients with FC.1)Among 103 children born to 64 epileptic parents, clinical seizures developed in 20 children (19.4%) and epileptic discharges in 27 (26.2%). Of clinical seizures, FC appeared in 13 cases (12.6%), recurrent afebrile seizures in 5 (4.9%), an isolated afebrile seizure (probably benign infantile convulsion) and a post-traumatic early seizure in one each (1.0%). According to Ohtahara' classfication, FC cases were subclassfied into 4 cases (3.9%) of simple FC,one case (1.0%) of complex FC,and 8 cases (7.8%) of epileptic FC.Thus, incidence of recurrent afebrile seizures (4.9%) was about 5 times higher than the preval … More ence rate of childhood epilepsy in general population, i.e.0.82% in Okayama Prefecture. Adding epileptic FC,it rose up to over 10 times. But, no increase was observed in the incidence of simple FC (3.9%) or non-epileptic FC (4.9%) compared to the reported prevalence rates of FC in the general population (5-10%).2)With 66 offspring of epileptic parents over 3 years of age, clinical seizures were noted in as many as 12 cases (42.9%) among 28 cases with additional genetic factor (AGF) within the second degree of relatives. This sate was significantly higher than 13.1% (5 cases) in 38 cases without such additional family history of convulsive disorders. Although FC occurred in 28.6% (8 cases) of the AGF group and 10.5% (4 cases) of the non-AGF group, epileptic FC consisted 87.5% (7/8 cases) of FC in the AGF group compared to 25.0% (1/4 cases) in the non-AGF group. These finding suggested that the inherited factor through epileptic parents is the epileptic predisposition.3)39 (34.5%) of 113 sibling of 88 FC children had FC,including 13 cases (11.5%) with epileptic FC whose EEG showed epileptic discharges. It was also noteworthy that no epileptic FC was noted in sibling of simple FC.4)Pseudo petit mal discharge and hypnagogic paroxysmal spike-wave activity, which have been considered characteristic to FC,were rarely detected in simple FC,but frequently in epileptic FC.Accordingly, these EEG pattern, particularly the latter, were suggested to relate the epileptic predisposition in infancy and early childhood.In conclusion, this investigation supported the difference between convulsive and epileptic predisposition. Epileptic FC may closely relate to the epileptic predisposition which is pathological, but simple FC will be a specific group based on the convulsive predisposition which will be universally predisposed to human being, regulating the convulsive threshold. Less