网友[飘过的云]：
急性CO中毒：
常累及基底节区，包括苍白球，壳核，尾状核，当然丘脑、侧脑室及皮层下白质，胼胝体，皮层，颞叶海马都可累及。
下图:急性期12h时FLAIR示正常，但DWI序列示顶、额、颞白质高信号，ADC图示相应部位低信号，提示细胞毒性水肿，16天后复查：壳核、尾状核出现高信号，而顶叶白质无高信号。
提示：CO中毒急性期：脑白质可能比基底节区对缺血更敏感，且具有可逆性，继之出现基底节区病变。
参考文献：Acute Carbon Monoxide Poisoning: Diffusion MR Imaging Findings （American Journal of Neuroradiology 24:1475-1477, August 2003）
CO中毒迟发性脑病：
指CO中毒恢复后一段时间（通常2-3周）后再次出现神经精神症状。MRI示双侧弥漫性，对称（或不对称性）脑白质病变，主要累及侧脑室旁和半卵园中心。
下图:上、中、下分别为三个病人的MRI。
参考文献：Delayed Encephalopathy of Acute Carbon Monoxide Intoxication: Diffusivity of Cerebral White Matter Lesions（American Journal of Neuroradiology 24:1592-1597, September 2003）
放射损伤：可引起局灶性脑坏死，弥漫性脑白质病变，脑萎缩，矿物化微血管病，大血管病等。
放射导致的脑白质脱髓鞘病变存在于38-50％全脑放射的病人中，经常是亚临床的，通过影像学检查发现，全脑放射比局灶性放射容易出现。影像上是对称性的、无强化及明显的占位效应。
参考文献：Radiation-induced changes in the central nervous system and head and neck（RadioGraphics, Sep 1996; 16: 1055）
Diffuse white matter injury in a 60-year-old patient who underwent whole-brain radiation therapy (4,500 cGy) for metastases from lung carcinoma. Contrast-enhanced CT ( a ) and T2-weighted MR ( b ) images obtained 9 months after radiation therapy demonstrate a diffuse abnormality throughout the white matter, seen as hypoattenuation on a and hyperintensity on b.
第二章 遗传性
线粒体神经胃肠脑肌病:
线粒体病为一大类由线粒体基因或(和)核基因异常所致的多系统疾病,多数患者表现为骨骼肌、心肌和中枢神经系统的损害,其他系统如胃肠道和周围神经等也可以被累及并成为主要临床表现之一。
其中线粒体神经胃肠脑肌病（MNGIE）是一种以胃肠道损害为主要表现的线粒体病,其临床特征多为青少年发病,主要临床症状包括胃肠道动力障碍、恶液质、进行性眼外肌麻痹、周围神经病及白质脑病,由于胃肠道动力障碍非常明显而常被误诊。作为一种常染色体隐性遗传病, 近几年发现其致病基因位于染色体22q13132区编码脱氧胸腺嘧啶核苷磷酸化酶( TP) 的基因。
临床症状：
1.胃肠道的症状:是最常见的首发表现,出现肠鸣、腹泻、早饱、腹部绞痛、恶心、呕吐、假性肠梗阻及胃轻瘫。吞咽困难常见,在少数患者中有显著的肝病。
2．恶液质:大部分患者消瘦,体重下降一般出现在胃肠道症状出现或加重时。有些患者身材矮小。
3．眼睑下垂、眼外肌麻痹常见。视觉系统的功能异常少见,个别患者有视网膜色素变性。偶有视神经萎缩。
4．周围神经病:周围神经病几乎出现在所有患者,主要表现为手套袜套样感觉丧失及腱反射消失。
5．白质脑病:脑白质变性出现在所有患者,但少见脑部症状者。
头颅MR I检查在所有MNGIE患者均有广泛的脑白质变性。胼胝体、内囊白质、基底节、丘脑、中脑、脑桥和小脑白质也常常被累及。
网友[fmuzzy]：
异染性脑白质营养不良（metachromatic leukodystrophy,MLD）
又名“脑硫脂沉积病”，是脑白质营养不良一类疾病中最常见的一型。是常染色体隐性遗传病，其生化缺陷是芳基硫酸酯酶A缺乏，脑硫脂蓄积体内。异常的沉积物见于中枢和末梢神经、肾、肝、胰、肾上腺、胆囊等器官。脑的病变以白质为主，有广泛脱髓鞘，沉积物常见于髓鞘内层。神经元和星形胶质细胞内也有沉积物。受累的组织呈异染性。
临床上MLD可分为晚婴型、幼年型和成年型。晚婴型最多见，出生时正常，多2岁左右起病，早期步态异常，共济失调，斜视，肌张力低下，自主运动减少，腱反射引不出，神经传导速度减慢。中期智力减退，反应减少，语言消失，病理反射阳性，不注视、瞳孔对光反应迟钝、可有视神经萎缩。晚期呈去大脑强直体位，偶有抽搐发作。有球麻痹征。病程持续进展，多在4～8岁间死于感染。
本病早期即有脑脊液蛋白增多，逐渐加重。末梢神经传导速度减慢。脑干听觉诱发电位在临床症状出现前即可有异常。脑CT检查可见脑白质病变由前额向后部发展。MRI在T2加权像可见白质高信号影，开始于脑室周围。
本病幼年型在4～15岁间起病，成年型在16岁以后起病。症状与上述相似，缓慢进展，晚期有明显精神行为异常。确诊需测白细胞或成纤维细胞的酶活性。患儿要摄入缺乏维生素A的食物，因为维生素A是合成硫苷脂的辅酶。治疗还可用骨髓移植。
MR imaging findings in metachromatic leukodystrophy in a 3-year-old female child (acute phase). Axial T2-weighted fast spinecho( a ), diffusion-weighted ( b ) and ADC map ( c ) images. The T2-weighted image shows extensive white matter disease. On the
diffusion-weighted image (b=1,000 s) the lesions areas appear to be quite uniformly hyperintense, but the ADC image provides inconsistent data. In the frontal and the deep parietal regions hyperintensities indicate increased water diffusion, therefore the
hyperintensities on the diffusion-weighted images, at least partially, may correspond to T2 shine-through. Definite hypointensities are suggested only in the parietal and central periventricular areas as well as the knee of the corpus callosum; these may represent myelin edema and active demyelination
肾上腺脑白质营养不良（adrenoleukodystrophy,ALD)
是一组病因不同的遗传性脂类代谢病，其病理特点是中枢神经进行性脱髓鞘以及肾上腺皮质萎缩或发育不良；生化代谢特点是血浆中极长链脂肪酸异常增高；遗传表现是细胞中过氧化物酶有结构的或酶活性缺陷，故属于过氧化物酶病的范围。在遗传方式上可分两种类型。一种是较多见的X连锁遗传，其中，起病于成人的变异型称为肾上腺脊髓神经病。另一种是常染色体隐性遗传，发生于新生儿，称为新生儿肾上腺脑白质营养不良。
治疗：用皮质激素替代治疗可延长生命。避免含长链脂肪酸的食物。骨髓移植可改善临床症状，防止痴呆。可测羊膜细胞中的二十六烷酸（C26：0）增高，以作产前诊断。
图：MR imaging findings in a 6-year-old male child in X-linked adrenoleukodystrophy. Axial fast FLAIR ( a ), gadolinium-enhanced T1-weighted spin-echo ( b ), diffusion-weighted ( c ) and ADC map( d ) images. Prominent and symmetrical white matter changes are shown in the parietal regions, within which the three distinct zones are well identified. The intermediate zone is markedly hyperintense on the FLAIR image and shows enhancement on the gadolinium enhanced T1-weighted image. This zone is hyperintense on the diffusion-weighted image (b=1,000 s) and hypointense on the ADC map, consistent with isotropically restricted water diffusion. Anterior to this, the zone of demyelination shows faint hypersignal on the diffusion-weighted image, but the signal is hyperintense on the ADC map, hence it mainly corresponds to T2-shine-through. The demyelinated zone is hypointense on the diffusion-weighted image and hyperintense on the ADC map, indicating increased, isotropical water diffusion due to demyelination and loss of tissue matrix. In the frontal regions the white matter is normal on all image types, but MR spectroscopic and quantitative diffusion data suggest abnormalities in the normal appearing white matter too in patients with X-ALD.
成人的变异型肾上腺脑白质营养不良称为肾上腺脊髓神经病
图：MR imaging findings in a 30-year-old male patient in adrenomyeloneuropathy.Axial T2-weighted fast spin-echo ( a, c ) and diffusion-weighted ( b, d ) images. The brainstem and cerebellar white matter abnormalities are obvious on the T2-weighted image ( a ), but no active demyelination is shown on the corresponding diffusion-weighted image ( b ). Supratentorially, the white matter lesions are limited to the posterior limbs of the internal capsules ( c ), where the diffusion-weighted image (b=1,000 s) suggests small areas of hypersignal posteriorly, which may indicate loss of physiological
anisotropy and restricted diffusion, consistent with some ongoing demyelination and myelin edema ( d )
Alexander病
病因尚不明。病理有脑白质弥散性脱髓鞘，血管周围有大量含有胶质细胞原纤维酸性蛋白的Rosenthal纤维。婴儿期起病，巨头，智力倒退，痉挛性瘫，癫痫发作。有的病例在儿童期或成年起病。CT检查可见白质弥散性低密度，额部最著。
Alexander disease in a 5-year-old boy with macrocephaly. ( a ) T2-weighted MR image shows symmetric demyelination in the frontal lobe white matter. The internal and external capsules and parietal white matter are also involved. ( b ) Photomicrograph (original magnification, �100; hematoxylin-eosin stain) of the pathologic specimen shows deposition of Rosenthal fibers (arrows).
Zellweger综合征
即“脑肝肾综合征”，是一种铁质累积症，属常染色体隐性遗传，肌张力极度低下，多发性小畸形，面容似先天愚型，智力障碍，且有运动障碍及惊厥。脑白质呈硬化和严重脱髓鞘改变。一般于生后6个月内死亡。
Zellweger syndrome in a 5-month-old girl. ( a ) T2-weighted MR image shows extensive areas of diffuse high signal intensity in the white matter. The gyri are broad, the sulci are shallow, and there is incomplete branching of the subcortical white matter, findings that suggest a migration anomaly with pachygyria. ( b ) On a T1-weighted MR image, the white matter abnormalities demonstrate low signal intensity.
编辑：西门吹血
