Asymptomatic self-limiting white matter lesions in the chronic phase of herpes simplex encephalitis

We report a 9-month-old girl with herpes simplex encephalitis. T(2)-weighted magnetic resonance imaging (MRI) on the 8th day of illness showed increased signal intensity in the gray and white matter of the bilateral lobes, especially the right temporo-parietal lobe. High voltage slow waves were recorded in the right parieto-occipital region on electroencephalography. She was discharged on the 34th day of illness without sequelae. On discharge, the high signal intensity on MRI had improved and the abnormal slow waves on electroencephalography had disappeared. At 4 months after the onset of illness, MRI revealed decreased signal intensities in T(1)-weighted images and increased signal intensities in T(2)-weighted images in the periventricular white matter adjacent to the posterior horns of the lateral ventricles. The white matter lesions had expanded at 9 months after the onset of illness. At 14 months after the onset of illness, the white matter lesions were reduced in size, and at 2 years after the onset of illness, they had completely disappeared. During 2 years follow-up after discharge, however, there were no neurological abnormalities corresponding to the lesions and her psychomotor development was normal. Although the mechanism underlying these white matter lesions had not been elucidated, an immune-mediated complication such as edema or demyelination is suspected. Repeat MRI studies over a long period are necessary to follow up a patient with herpes simplex encephalitis.     

Magnetic resonance imaging pattern recognition in hypomyelinating disorders

Hypomyelination is observed in the context of a growing number of genetic disorders that share clinical characteristics. The aim of this study was to determine the possible role of magnetic resonance imaging pattern recognition in distinguishing different hypomyelinating disorders, which would facilitate the diagnostic process. Only patients with hypomyelination of known cause were included in this retrospective study. A total of 112 patients with Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis, Salla disease and fucosidosis were included. The brain scans were rated using a standard scoring list; the raters were blinded to the diagnoses. Grouping of the patients was based on cluster analysis. Ten clusters of patients with similar magnetic resonance imaging abnormalities were identified. The most important discriminating items were early cerebellar atrophy, homogeneity of the white matter signal on T(2)-weighted images, abnormal signal intensity of the basal ganglia, signal abnormalities in the pons and additional T(2) lesions in the deep white matter. Eight clusters each represented mainly a single disorder (i.e. Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, infantile GM1 and GM2 gangliosidosis, Pelizaeus-Merzbacher-like disease and fucosidosis); only two clusters contained multiple diseases. Pelizaeus-Merzbacher-like disease was divided between two clusters and Salla disease did not cluster at all. This study shows that it is possible to separate patients with hypomyelination disorders of known cause in clusters based on magnetic resonance imaging abnormalities alone. In most cases of Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis and fucosidosis, the imaging pattern gives clues for the diagnosis.     

Adrenoleukodystrophy. Value of contrast-enhanced MR imaging

In its early stage adrenoleukodystrophy (ALD) is characterized by hypodensity at CT and signal abnormalities at RMI (low-intensity signal on T1-weighted sequences, high-intensity signal on T2-weighted sequences) in the white matter of the parieto-occipital region and the splenium of the corpus callosum. These CT and RMI abnormalities are suggestive of ALD in children with progressive alteration of the superior brain functions, but they are not specific of the disease. The authors present two cases of ALD and underline the almost pathognomonic value of contrast-enhanced ribbons found at the periphery of low-intensity signal plaques after gadolinium injection. These areas of blood-barrier disruption on a background of inflammation and active demyelination appear, on T2-weighted sequences, as ribbons of low-intensity signal within plaques of high-intensity signal. MRI is also superior to CT in detecting abnormalities located in the posterior fossa, notably lesions of the auditory fibres.     

Cerebral amyloid angiopathy presenting as a pseudotumor: 2 cases with spontaneously favorable outcomes

A rare clinical and radiographical presentation of cerebral amyloid angiopathy mimicking a brain neoplasm was observed in 2 patients. The signs and symptoms included seizures and focal parieto-occipital dysfunction in 1 case, massive left hemisphere dysfunction and akinetic mutism in the other. Brain CT and MRI showed nonspecific focal white matter abnormalities suggestive of the diagnosis of low-grade glioma. Gradient echo T1 and T2-weighted images showing multiple areas of signal void suggesting multiple disseminated petechial hemorrhages led to the diagnosis of cerebral amyloid angiopathy. An eventless brain biopsy confirmed the diagnosis. The neuropathology examination disclosed amyloid angiopathy of the pial and cortical vessels selectively stained by anti A-beta protein antibodies. The clinical course was remarkable in the two cases with almost complete clinical recovery without any particular treatment.     

Magnetic resonance imaging of the brain in phenylketonuria

To investigate the correlation between the abnormalities of magnetic resonance imaging (MRI) of the brain and blood phenylalanine (Phe) levels in phenylketonuria (PKU) and hyperphenylalaninemia (HPA), we reviewed MRIs from 16 patients with early treated PKU and HPA. Their ages ranged from 4-24 years and were found by mass screening and treated from early infancy, and 5 patients with late detected PKU who were aged 24-33 years. The former patients had no remarkable neurological signs or symptoms. One patient of the latter had severe mental retardation and 3 patients had mild to border mental retardation. Axial T1-weighted and T2-weighted spin echo sequences, fluid attenuated inversion recovery MR sequences (FLAIR) through the brain were performed. The scans were graded according to the extent of increased signal intensity of white matter on T2-weighted and FLAIR sequences. To investigate the influence of plasma Phe levels, three approaches were used. Firstly an average of all yearly serial blood Phe concentration was calculated for each patient, then Phe was determined for a period of 6 months and 12 months prior to MRI, and also for their lifetime up to their age at the time this study began. These average blood Phe levels were classified into four categories: group A:Phe level below 5 mg/dl, group B:5-8 mg/dl, group C:9-12 mg/dl, group D:above 12 mg/dl. MRI findings were not significant in group A. Remarkable high signals of white matter were obtained in group C and D, except for one patient in group D whose MRI finding was normal. MRI findings correlated to long-term dietary control stronger than those of 6 months prior to MRI. The clinical significance of MRI abnormalities is still unclear, and further study is required to clarify the relationship of the MRI findings and clinical conditions.     

Early diagnosis in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL): the role of MRI

The aim of our work was to evaluate the early presence of white matter changes on magnetic resonance imaging (MRI) in young asymptomatic children of patients with full-blown cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in whom DNA analysis revealed a Notch3 Cys146Tyr missense mutation on chromosome 19. Brain MRI was performed in all subjects using axial and coronal spin-echo proton density and T2-weighted images, axial fluid-attenuated inversion recovery (FLAIR) and sagittal and axial T1-weighted images. In asymptomatic subjects with Notch3 gene mutation, MRI showed small T2 hyperintense foci in periventricular and subcortical white matter. Routine use of MRI in the initial phases of a CADASIL diagnostic work up and the subsequent recognition of early abnormal findings in asymptomatic subjects may lead to prompt diagnosis of the disease in these patients. Moreover, these findings suggest that genetic screening is warranted in the presence of a suspect clinical history with specific MRI abnormalities.     

Temporopolar changes in temporal lobe epilepsy: a quantitative MRI-based study

OBJECTIVES: To quantify the morphologic changes of temporopolar structures to better understand the pathophysiology of anterior temporal white matter increased T2 signal observed in temporal lobe epilepsy (TLE). METHODS: MRI was performed in 30 patients with TLE and in 30 normal control subjects and independently assessed by visual analysis and quantitative measurements. Specifically, the temporal pole (TP) volume, as well as its gray and white matter components, was measured using three-dimensional T1 MR images and a semiautomatic protocol. The authors tested whether the presence of an increased T2-weighted signal in the anterior temporal white matter was associated with significant TP atrophy. The associations between the TP volume and MRI signs of hippocampal sclerosis, age at onset, seizure frequency, duration of illness, and a history of febrile convulsions were also studied. RESULTS: Both right and left TLE populations demonstrated a reduction of the temporopolar white and gray matter volumes ipsilateral to seizure onset (p < 0.02 in right TLE; p < 0.0001 in left TLE). Twenty-two patients (72%) exhibited significantly abnormal TP volume measurements, which correctly lateralized the epileptogenic zone in all cases. The presence of an increased T2-weighted signal in the anterior temporal white matter (ISWM), but not that of hippocampal sclerosis, was associated with a greater TP volume asymmetry index (p < 0.05). CONCLUSIONS: The temporal pole is frequently atrophic ipsilateral to seizure onset in refractory TLE. The association between TP atrophy and ISWM suggests that both abnormalities might derive from a common pathologic process.     

Clinical symptoms and characteristic MR spectroscopic findings in Pelizaeus-Merzbacher disease

Clinical symptoms and MR spectroscopic findings were studied on 4 cases of Pelizaeus-Merzbacher disease including 1 autopsy case. Common symptoms were severe mental retardation and spastic tetraplegia. These cases had nystagmus, and one had involuntary athetotic movement. Genetical diagnosis revealed in 2 cases, duplication of proteolipid protein (PLP) and deletion in 1, whereas one case had no abnormality of PLP gene. MRI indicated the reversal of signal intensities on T1- and T2-weighed images, a characteristic finding of PMD MR spectroscopy demonstrated a pattern of NAA in 3 cases. This was specific to PMD because other white matter diseases show a decrease in NAA. In conclusion, MRS was useful to differentiate PMD from other white matter diseases.     

Leukoencephalopathy in HTLV-I-associated myelopathy: MRI and EEG data

Magnetic resonance imaging (MRI) of the brain and electroencephalography (EEG) were carried out for patients with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM). Nineteen of 22 patients (86%) had abnormalities on brain MRI and/or EEG. Thirteen patients showed high signal intensity lesions scattered in the cerebral white matter, as seen on the T2-weighted MRI images. The lesions were mostly located in the subcortical and deep cerebral white matter and were not contiguous with the lateral ventricles. Patients with abnormalities on the brain MRI had a longer duration of disease and a greater disability than did those without MRI abnormalities. The EEG records showed definite abnormalities in 9, and minor abnormalities in 5. All patients with HAM for more than 5 years showed definite evidence of cerebral involvement. Our findings strongly suggest that a multifocal pathological process over the entire CNS is probably a common occurrence in HAM.     

MRI and CT findings in Krabbe disease

The progression and characteristics of magnetic resonance imaging (MRI) and computed tomographic (CT) findings in 3 patients with infantile Krabbe disease (i.e., globoid cell leukodystrophy or galactocerebroside beta-galactosidase deficiency) are reported. We obtained initial CT and MRI studies when patients demonstrated hyperirritability and hypertonicity. The following results facilitated early diagnoses: increased density in the thalami, corona radiata, and cerebellar cortex on CT and plaque-like, high signal intensity in the periventricular region and cerebellar white matter on MRI T2-weighted images. After severe motor and mental deterioration and spasticity had developed, progressive brain atrophy, low density in the white matter, and calcification-like, symmetric, punctate high-density areas in the corona radiata were evident on CT and high signal intensity in T2-weighted images and low signal intensity in T1-weighted images in the white matter were present on MRI. In particular, linear patterns were observed in the centrum semiovale on MRI.     

高分辨MRI在Ⅰ型局灶性皮质发育不良患儿术前评估中的应用

目的 探讨高分辨MRI成像在儿童Ⅰ型局灶性皮质发育不良(FCD)术前评估中的价值.方法 回顾性分析52例经病理学证实的FCD Ⅰ型患儿的MRI及相关临床资料,比较高分辨成像与MRI常规序列对Ⅰ型FCD各主要MRI征象(局灶性灰白质分界模糊、局灶性皮质结构异常、白质异常信号灶及局限性脑叶萎缩/发育不全)的检出率,以及对病...     

Normalization of T2 signal abnormalities in hemispheric white matter with liver transplant

OBJECTIVE: To determine whether edema can be assessed by MRI using T2-weighted signal intensity of hemispheric white matter in cirrhotic patients. METHODS: Fast-FLAIR and magnetization transfer images were obtained before (24) and after (11) liver transplantation. T2-weighted abnormalities on baseline scans and their time-course changes were analyzed and compared with MT ratios (MTR). RESULTS: Fast-FLAIR baseline images showed faint to substantial, bilateral, symmetric increased signal intensity along the hemispheric white matter in or around the corticospinal tract in 23/24 patients. After liver transplantation the signal abnormalities gradually recovered. This gradual decrease in signal intensity correlated with an increase in MTR values. CONCLUSION: Asymptomatic symmetric high-signal intensity in the hemispheric white matter on fast-FLAIR MR images is present in cirrhosis. Normalization of this finding after successful liver transplantation and its correlation with MTR values suggest that this signal abnormality reflects mild edema.     

Use of computed tomography, magnetic resonance imaging, and localized 1H magnetic resonance spectroscopy in Canavan's disease: a case report

The neuroradiological evaluation of Canavan's disease in a 38-month-old girl is discussed. Computed tomography showed diffuse symmetrical low attenuation values of the subcortical and deep cerebral white matter. Magnetic resonance imaging demonstrated symmetrical diffuse low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. With the use of 1H magnetic resonance spectroscopy, we were able to show elevated levels of N-acetylaspartic acid in the occipital lobe of our patient. The in vivo measurement of N-acetylaspartic acid in the brain by 1H magnetic resonance spectroscopy offers an additional noninvasive diagnostic test for establishing the diagnosis of Canavan's disease. With the increasing availability of magnetic resonance spectroscopy, clinicians may be able to confirm the diagnosis of Canavan's disease immediately after magnetic resonance imaging reveals the typical abnormalities of the white matter.     

Disappearance of a white matter lesion in incontinentia pigmenti

We report a 12-month-old Japanese female with incontinentia pigmenti, in whom magnetic resonance imaging (MRI) disclosed a small transient lesion in the white matter. After birth, she developed some vesicular skin eruptions that mainly involved the lower extremities. These skin lesions increased in size and number and became hyperpigmented within 2 weeks. At 1 month of age, MRI revealed a small hypointense lesion on T(1)-weighted imaging, with water density on T(2)-weighted imaging, in the right centrum semiovale. At 4 months of age, her hyperpigmented lesions had faded, and at 7 months of age, MRI disclosed the disappearance of the previously observed abnormality. She exhibited no neurologic abnormalities. No cases have been reported concerning a transient lesion in the white matter revealed by MRI in incontinentia pigmenti. Although the pathogenesis is unknown, transient central nervous system involvement might have occurred in early infancy as did the fading skin lesions.     

Reversible bilateral pyramidal tract lesions after hypertensive crisis and cerebral seizures

This is a rare case of reversible high signal-intensity changes along the pyramidal tracts in a patient with reversible posterior leukoencephalopathy syndrome (RPLS). A 38-year-old man was admitted to hospital for loss of consciousness and generalized seizures. His systolic blood pressure was 220 mmHg. Neurological examination revealed bilateral pyramidal-tract signs, and paresis of the right arm. Initial MRI showed increased signal intensities on T2-weighted, FLAIR and diffusion-weighted imaging in the following regions: bilateral temporo-occipital white matter and cortex, dorsal parts of the lentiform nuclei, bilateral caudate nuclei and external capsule. High signal intensities were observed in the pyramidal tracts as well. On patient follow-up, MRI signal abnormalities and clinical symptoms were completely resolved after antihypertensive treatment.     

Abnormal white matter appearance on term FLAIR predicts neuro-developmental outcome at 6 years old following preterm birth

Preterm infants are at significant risk of neuro-developmental disorders at school-age. MRI is a potentially useful screening tool of such disorders. Using FLAIR imaging in the preterm infants at term, here we demonstrate that abnormal low-intensity signal in the white matter predicts the neuro-developmental outcome at 6 years.

Study design

Clinical factors associated with white matter appearance on MRI obtained at term were investigated in 210 preterm infants.

Results

Low-intensity signal on FLAIR imaging was commonly observed (69%) at <2 months corrected-age. Its incidence correlated with corrected-age at scan, maternal pyrexia and cystic periventricular leukomalacia. Low-intensity signal on FLAIR significantly correlated with performance and full-scale developmental quotients, whereas diffuse high-intensity signal on T2-weighted imaging correlated only with the full-scale developmental quotient at 6 years (n = 75, WISC-R). FLAIR imaging, but not T2-weighted imaging, predicted mild neuro-developmental delay.

Conclusions

FLAIR appeared to detect subtle white matter injury related with neuro-developmental disorders at school-age, whereas T2-weighted imaging seemed to identify relatively more severe injury. FLAIR is a potentially sensitive screening tool that is readily available and easily interpretable.     

Laminar cortical necrosis in adrenal crisis: sequential changes on MRI

We describe the serial magnetic resonance imaging (MRI) findings in a six-year-old girl with congenital adrenal hyperplasia, who presented with seizures and unconsciousness during a hypoadrenal crisis. Initial neuroimaging revealed the presence of brain edema with high signal changes in the fronto-parietal cortex on diffusion-weighted MRI. The brain edema worsened four days into admission, and by day 14 low-density areas were seen over the frontal lobes bilaterally using computed tomography (CT). Follow-up MRI at between one and two months of admission revealed extensive white matter lesions with high intensity on T2-weighted images (T2WI) and fluid-attenuated inversion recovery (FLAIR) images, which extended into deep cortical layers. Additionally, linear lesions with high signal change on T1-weighted imaging developed in the superficial cortical layers, with frontal predominance. This layer appeared isointense on T2WI and high intensity on FLAIR images, suggesting laminar cortical necrosis. Two months later, linear, cavitary lesions appeared in the middle cortical layers between the aforementioned superficial laminar abnormality and deep cortex/white matter lesions. The high-intensity signals in the deep cortical layers remained contiguous with the white matter lesions. This unique type of multi-layered cortical lesion may have resulted from a complex combination of hypoglycemia and hypoxia/ischemia in the setting of adrenal insufficiency.     

吸食海洛因致海绵状白质脑病的CT及MRI诊断

目的评价海洛因中毒所致的海绵状白质脑病的CT、MRI表现及诊断价值.方法搜集6例海洛因海绵状白质脑病的CT及MRI资料,全部患者均进行MRI检查,检查序列包括T1WI、T2WI、FLAIR序列,其中2例同时行颅脑CT扫描. 结果全部患者MRI显示对称性双侧小脑半球、大脑半球后部、内囊后肢、胼胝体压部、脑干等皮质下白质为主的多发性大片状长T1、长T2信号,加强后病灶无强化;2例行头颅CT检查显示两大脑半球皮质下白质、基底节及两侧小脑呈对称性广泛低密度灶,无占位效应.结论海洛因中毒所致的海绵状白质脑病具有特征性的MRI表现,MRI对本病的诊断具有重要价值.     

Computed tomography and magnetic resonance imaging of the brain in Hurler's disease

Computed tomographic (CT) and magnetic resonance imaging (MRI) scans of the brain in five patients with Hurler's disease are described and compared to the few available reports in the literature. Computed tomographic scans revealed low attenuation areas in the centrum semiovale and peritrigonal white matter. Ventriculomegaly was not a prominent feature in our patients, compared to those previously reported. In two patients, CT were normal. The most prominent magnetic resonance imaging abnormalities were the presence of radially oriented cystic areas in the centrum semiovale, peritrigonal white matter, corpus callosum, and pericallosal region. Magnetic resonance imaging abnormalities were present in all patients, even when CT scans were normal. Abnormalities on CT and MRI scans tended to be more prevalent in the posterior regions. Magnetic resonance imaging proved to be a more reliable imaging method in Hurler's disease. T1-weighted images delineated the cystic areas more clearly, whereas T2-weighted images were more sensitive in detecting small white-matter abnormalities. Magnetic resonance imaging abnormalities correlated well with known neuropathologic alteration in this disease. It is suggested that the cystic areas seen on MRI correspond to perivascular lacunae seen in histopathologic material.     

Sequential magnetic resonance imaging and neurophysiological studies in a patient with inferior spinal cord infarction]

A 66-year-old woman suddenly developed anterior spinal artery syndrome with complete flaccid paraplegia, superficial sensory disturbance caudally to the L5 dermatome level with preservation of deep sensation, incontinence, and absent deep tendon reflexes in both legs. An MRI of the whole spine and an analysis of the CSF 4 hours after onset were normal. The electrophysiological study showed an absence of F wave on the posterior tibial nerve stimulation on admission, while the peripheral nerve conduction velocities and amplitudes of upper and lower limbs were normal. T2-weighted MRI 4 days after onset demonstrated an area of high signal intensity in the gray and white matters of the epiconus and conus medullaris, and T1-weighted MRI showed the swelling. Three weeks later, F wave became evoked nd the high signal areas on axial T2-weighted MRI were localized in the bilateral anterior horns of the gray matter. T1-weighted MRIs after an administration of Gd-DTPA 3 and 7 weeks after onset demonstrated an enhancement of the ventral roots of the lumbar nerves and cauda equina, while the enhancements disappeared 8 months after onset. The patient was finally able to walk independently over 10 meter. An absent F wave was an only positive finding at the hyperacute (hours after onset) stage of the spinal cord infarction.