患者1，7岁男孩,跛行并左侧肢体无力。7-year-old male, limp with left sided weakness.
患者2，正常发育的6岁男孩出现动作改变和不良共轭凝视。developmentally normal 6-year-old boy with new onset behavioral changes and dysconjugate gaze.
figure 1: axial non contrast ct demonstrates symmetric low attenuation in the temporal-parietal white matter. note involvement of the splenium of the corpus callosum (red arrows).图1:轴位的平扫ct显示对称性的低密度影在颞枕叶脑白质区,需要注意的是病变累及胼胝体的压部.
figure 2 andfigure 3: axial t1 and t2 images demonstrate symmetric t1 hypointensity and t2 hyperintensity in the temporal-parietal white matter corresponding to the low attenuation on ct. note relative sparing of the subcortical u-fibers (yellow arrows).图2.3:轴位的t1和t2显示颞枕叶脑白质区对称性的长t1长t2信号,与ct上低密度相符合.注意相对保留正常的皮质下u形纤维(黄色箭头)
figure 4: axial post gadolinium t1 weighted image demonstrates abnormal hypointensity involving the temporal-parietal white matter, with enhancement of the leading edge (blue arrows) which represents active demyelination.图4:轴位的增强t1序列显示累及颞枕叶的低信号影,有边缘强化(蓝箭),代表活动的脱髓鞘病变
figure 5 mr spectroscopy demonstrates increased choline and decreased naa, findings that are non specific but consistent with adrenal leukodystrophy. note the presence of lactate an indicator of necrosis.图5:mrs显示胆碱峰增高和naa峰降低,这些改变是非特异性的,但是符合肾上腺脑白质营养不良,注意乳酸峰出现代表坏死
figure 1 and figure 2: axial flair and t2 weighted images show bilateral confluent deep periatrial white matter and splenium (red arrow in figure 3) signal abnormality. there is notable sparing of the subcortical u-fibers (blue arrows), better seen on the t2 weighted images where there is better gray matter-white matter differentiation.图1和图2:轴位flair和t2序列显示双侧脑室周白质及胼胝体压部(红色箭头)信号异常,特别要注意的是皮质下u形纤维的保留(蓝色箭头).在t2序列上显示的更好.
figure 3,figure 4, and figure 5 are axial t1 pre and post contrast images. there is inherent t1 hyperintensity involving the periatrial white matter (yellow arrows in figure 3) consistent with calcification as was seen on concurrent ct (not shown). post contrast images show flame shaped areas of enhancement (green arrows in figure 4 and figure 5) at the margins of the flair signal abnormality, the classic “leading edge” of active demyelination.图3,4,5和轴位的t1平扫和增强扫描,累及到室周白质的t1高信号影(图3黄箭)符合钙化(ct上证实,未显示).增强后显示flair异常信号的边缘火焰状强化(图4.5 绿箭),这是典型的活动性脱髓鞘"缘".
figure 6,figure 7, figure 8,figure 9: axial t2 weighted images show bilateral symmetric t2 prolongation involving the corticopontine and corticospinal tracts (white arrows).图6-9:显示双侧皮质桥脑束和皮质脊髓束的对称性t2高信号影.
【影像诊断】：adrenal leukodystrophy 肾上腺脑白质营养不良
【诊断要点】：adrenal leukodystrophy (ald) is an x-linked hereditary disorder classically affecting developmentally normal young boys who develop behavioral, visual, auditory and motor problems in childhood.肾上腺脑白质营养不良是一种x连锁遗传病,典型的累及发育正常的男孩，在儿童期出现行为、视觉、听力和运动异常。
nearly all patients are between the ages of 5 and 12 years old.几乎所有的病人都是在5-12岁。
classic imaging findings of ald include bilateral, confluent periatrial (parietal-occipital) deep white matter t2 prolongation with sparing of the u-fibers, and a “leading edge” of enhancement that represents a border of active demyelination.典型的ald影像包括双侧、融合性（顶枕部）深部白质长t2信号伴皮质下u形纤维的保留，边缘强化代表活动性脱髓鞘边缘。
【讨论】：adrenal leukodystrophy is a hereditary disorder caused by impaired beta-oxidation of very long chain fatty acids (vlcfa). various forms exist, each named according to the age of presentation, including neonatal, childhood, adolescent and adulthood. another variant, in which there is severe involvement of the spinal cord rather than the cerebrum, is termed adrenomyeloneuropathy (amn).
the disease is caused by a mutation of the ald gene which codes for a peroxisomal membrane protein. transport of very long chain fatty acids into the peroxisome is consequently restricted. this results in reduced supply of shorter chain fatty acids within the peroxisome available for synthesis of complex lipids and proteins, which are myelin components.
the defective myelin is more easily broken down by the body’s normal physiologic functioning and the resulting pathophysiologic processes which include a severe inflammatory demyelination that predominates in the cerebral white matter and axonal degeneration that predominates in the posterior fossa and spinal cord. these processes manifest radiologically as three zones in the cerebral white matter: zone a, a central burned out zone containing only astrogliosis, zone b, an inflammatory zone peripheral to the central zone containing perivascular inflammatory cells and demyelination where axons are preserved, and zone c, site of demyelination without inflammation.
clinically, patients suffering from the childhood variant of ald develop normally initially, but then present with behavioral changes and progressive visual, auditory and motor dysfunction between the ages of 4-10. diagnosis is usually made by laboratory evaluation of very long chain fatty acid levels once there is clinical suspicion. treatment options are limited and aimed at lowering levels of vlcfa’s through dietary restriction, consumption of lorenzo’s oil and lovastatin therapy. bone marrow transplantation has also shown to be of benefit in some cases. imaging is helpful as an adjunctive tool to evaluate the extent of disease at presentation and to assess for evolution of the disease during treatment.
the classic picture of ald is that of confluent, bilateral periatrial (parietal-occipital) deep white matter signal abnormality with sparing of the subcortical u-fibers. the pathological basis for the signal abnormality is a combination of demyelination and gliosis. the signal abnormality demonstrates a “leading edge” of enhancement which reflects blood brain barrier breakdown at sites of active demyelination at the margins of the signal abnormality. calcifications along the trigone have also been noted as late sequelae, and are present in this case.
loes et al. have described five patterns of involvement, which when considered in the context of patient age at presentation, may give a clue to prognosis. pattern 1 describes involvement of the parietal-occipital white matter and splenium and is associated with rapid progression with younger age of presentation and with enhancement. pattern 2 is that of frontal white matter and genu involvement, and has a similar prognosis to that of pattern 1. pattern 3 is that of corticospinal tract involvement, usually seen in adults and demonstrates slower progression. pattern 4 is that of corticospinal tract involvement associated with abnormality of the cerebellar white matter, which is seen in adolescents and is also associated with slower progression. finally, pattern 5 is that of concomitant frontal and parietal-occipital white matter abnormality, seen mostly in children and having a rapidly progressive course.
proton mr spectroscopy demonstrates decreased naa and myo-inositol and increased choline, glutamine, glutamate and lactate. decreased naa/cr and naa/ch ratios and increased ch/cr ratios are characteristic. the classic imaging findings are virtually pathognomonic with limited differential diagnosis. another peroxisomal disorder, acyl coa oxidase deficiency, has similar imaging findings, but the clinical presentation is much different.