Myelination of the corpus callosum in the cat: time course, topography, and functional implications

The parameters of myelin development were ascertained in two specific regions of the corpus callosum in a series of cats aged 12 postnatal days through adult. The posteriormost portion of the splenium and the anterior-most portion of the genu were examined in cross section by using the electron microscope. Measurements were made to determine the age at which myelin first appeared, the number and distribution of myelinated fibers, the number and distribution of myelin lamellae, and cross-sectional area of ensheathed axons during development. The results indicate that myelination begins and ends earlier in the anterior region of the callosum. Measurements of myelin lamellae indicate similarities between anterior and posterior regions of the callosum, although development occurs earlier in the genu than in the splenium. No evidence was found for a sequence in the size of axons acquiring myelin sheaths, except that extremely small fibers are the last to begin myelinating. Myelination of the splenium of the corpus callosum begins at the very end of the behavioral and physiological critical period for the corpus callosum's role in visual functional development (Elberger: Behav. Brain Res. 11:223-231, '84; Elberger and Smith: Exp. Brain Res. 57:213-223, '85). Since myelination of a pathway is used as an index of functional reliability, this indicates that the basis for the callosal role in developing visual functions is probably not based on its physiological input to visual cortex.     

Nonconvulsive status epilepticus manifesting as rapidly progressive dementia and infarction in the splenium of the corpus callosum: A case report

Rationale:Nonconvulsive status epilepticus (NCSE) is a heterogeneous disease with multiple subtypes. NCSE poses great diagnostic and therapeutic challenges due to the lack of typical symptoms. Here, we report a case of NCSE manifesting as rapidly progressive dementia (RPD) and infarction in the splenium of the corpus callosum. Additionally, the relevant literature was reviewed.Patient concerns:A 63-year-old man presented with RPD. Electroencephalogram (EEG) revealed NCSE, and brain magnetic resonance imaging (MRI) showed an isolated infarction in the splenium of the corpus callosum. Mini-mental state examination showed moderate cognitive impairment (14/30 points).Diagnosis:A diagnosis of NCSE with RPD and infarction in the splenium of the corpus callosum was made.Interventions:The patient was treated with intravenous diazepam (10 mg), oral levetiracetam (1.0g twice daily), oral sodium valproate (0.2g twice daily), and intramuscular phenobarbital sodium (0.2g once daily).Outcomes:After the treatment, the symptoms were improved. The patient could answer questions. Repeated EEG showed that the background a rhythm was slightly overdeveloped, and no clinical or electrical seizures were observed. After discharge, the patient was treated with oral levetiracetam (1.0g twice daily) and oral sodium valproate (0.2g twice daily) for 6 months. At the last follow-up, the patient had clear consciousness, sensitive response, and fluent answering ability. Repeated mini-mental state examination showed that his cognitive function was significantly improved (28/30 points); nevertheless, the lesion in the splenium of corpus callosum remained unchanged on MRI.Lessons:NCSE manifesting as RPD and infarction in the splenium of the corpus callosum is extremely rare. Epileptic events and focal infarction are usually overlooked in patients with dementia, and the diagnostic value of MRI and EEG should be highlighted     

胼胝体压部可逆性病变的MRI诊断与临床分析

目的探讨胼胝体压部(splenium of the corpus callosum,SCC)可逆性病变的MRI表现及临床特点。方法回顾性分析8例脑MRI表现为单纯胼胝体压部可逆性病变患者的临床和影像学资料。结果 8例患者的SCC可逆性病变均为继发性,原发病分别为脑内感染5例,肝豆状核变性、低血糖脑病及脑外伤各1例。8例患者均急性起病,临床表现为发热、头痛5例,急性意识障碍2例,肌张力增高2例,颈强2例,均符合原发病的临床表现。8例均行脑MRI检查,均表现为T1低或等信号,T2及FLAIR序列高信号,DWI高信号(提示细胞源性水肿),其中4例行增强扫描未见强化。8例患者均于临床症状好转或消失后复查MRI提示病灶消失。结论 SCC可逆性病变在多种疾病中均可出现,无该病变相关的特异性临床表现,MRI表现提示病灶为细胞源性水肿可能。     

基于汉字左半错读机制的治疗性阅读策略及其效果

目的:明确基于汉字左半错读机制所设计的一种新的治疗性阅读策略(注视汉字左边界),对左半错读患者KY阅读成绩的影响。方法:让KY分别在自然注视条件下以及注视汉字左边界条件下各朗读一组匹配的汉字,观察是否后者的朗读成绩显著高于前者。并对另一组在自然注视条件下阅读错误的汉字采用注视其左边界阅读的方式,观察阅读正确率是否提高。结果:KY对于自然注视组的汉字出现左半错读,正确率较低,而注视左边界组的汉字朗读正确率显著提高(P=0.001)。对于另一组自然注视条件下错读的汉字,采用注视其左边界的阅读策略后正确率也显著提高(P0.001)。结论:这种基于左半错读机制所采用的注视汉字左边界的治疗性阅读策略是有效的。     

儿童伴可逆性孤立胼胝体压部病变的轻度脑炎/脑病临床及影像学特点

目的:分析儿童伴可逆性孤立胼胝体压部病变的轻度脑炎/脑病(MERS)的临床特征及影像学特点。方法:选取2011年8月至2015年8月就诊于内蒙古医科大学附属医院儿科的15例临床诊断为MERS的患儿,进行头颅MRI、腰椎穿刺、长程EEG、血生化及病原体等检查,并对其临床特征进行分析。结果:15例患儿均有发热、咳嗽或腹泻等前驱感染症状,之后出现一过性轻度嗜睡,伴有下列症状之一:惊厥、头痛伴呕吐、共济失调。查体多数无神经系统阳性体征。其中2例血检支原体鄄IgM(+),3例大便检测出轮状病毒鄄IgM。血生化大多显示低钠血症。所有患儿头颅MRI均出现胼胝体压部孤立性、边界清楚的圆形或椭圆形病灶。经常规抗感染治疗后,1~2周内复查头颅MRI上述病灶完全恢复正常。结论:儿童MERS是一种急性胼胝体压部可逆性病变的轻微脑病,可能与感染相关,经抗感染治疗,1~2 周内可完全恢复。