Multiple sclerosis in children: value of serial MR studies to monitor patients

A series of six children with clinical (4) and laboratory (2) evidence of multiple sclerosis is described. The mean age at onset was 12 years and the female-male ratio was 5:1. All patients had white matter abnormalities on initial MR scans. On follow-up MR studies, performed every 3 to 5 months, all children exhibited changing patterns of CNS signal abnormalities. In three cases, clinically silent brain lesions were detected. In four patients with an acute clinical attack, large lesions were present, demonstrating a lamellar structure on T1- and T2-weighted images. The lesions were seen best on long TR/short TE spin-echo sequences. Combined sagittal and axial series with EKG gating and flow-compensation technique were best for MR follow-up studies. Our results show that MR is useful for monitoring patients with multiple sclerosis.     

Preliminary experience of magnetic resonance imaging in neurosarcoidosis

Summary Twelve MR scans performed on seven patients with neurosarcoidosis are presented. The most common abnormalities were ventricular enlargement (four patients) and diffuse periventricular white matter changes (three patients). Infarcts were seen in three patients and mass lesion in one. The lesions were seen in both T1 and T2 weighted images. The results are compared with CT findings. MRI seems to be more sensitive than CT in detecting white matter changes and infarcts. Ventricular enlargement and granulomas were equally well seen with both modalities.     

MR imaging of the brain in patients with migraine headaches

Forty-one patients with migraine headaches were referred for MR imaging of the brain. Intermediate and T2-weighted images were obtained to determine the frequency of areas of high intensity within the white matter. The average age of these patients was 29.8 years; only five were over 40 years old. Each patient was evaluated in the axial plane with long TR/short and long TE images. Twenty-three patients also had T1-weighted short TR/short TE MR scans; enhancement with gadopentetate dimeglumine was used in three patients. Intracranial abnormalities were seen in only six patients: foci or white matter high intensity on intermediate and T2-weighted images in five and a venous angioma in one. Prior studies have indicated that parenchymal brain abnormalities may be found in up to 46% of patients with migraines. The current study demonstrated parenchymal brain lesions in only 12%. This study suggests that the frequency of foci of high intensity seen on long TR sequences in the migraine patient is much lower than previously reported, especially in patients under 40 years old (5.5% in our series).     

MR of the brain in mitochondrial myopathy.

PURPOSETo determine the spectrum of MR findings in patients with mitochondrial myopathy and correlate them with central nervous system symptoms and signs.METHODSWe performed a prospective evaluation of the MR findings of eight patients with mitochondrial myopathy (three with Kearns-Sayre syndrome and five with chronic progressive external ophthalmoplegia), six of whom had central nervous system symptoms or signs (ataxia, sensorineural hearing loss, or cognitive dysfunction).RESULTSAll six patients with neurologic symptoms or signs had multiple abnormal MR findings, whereas patients without neurologic symptoms had either normal MR findings (one patient) or the solitary finding of cortical atrophy (one patient). Abnormal MR findings consisted of cerebral cortical atrophy (seven patients), cerebellar atrophy (six patients), and hyperintense signal abnormalities on T2-weighted images within the cerebral white matter (three patients), cerebellar white matter (one patient), basal ganglia (three patients), brain stem (one patient), and thalamus (one patient). In two patients, the cerebral white matter signal abnormalities were primarily peripheral and involved the arcuate fibers. All patients with ataxia had abnormal cerebellar findings on MR imaging, but there was poor correlation between other neurologic features and MR findings.CONCLUSIONSCerebral and cerebellar atrophy are the most common MR findings in Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia. White matter and deep gray nuclei abnormalities, presumed to result from the diffuse spongiform encephalopathy reported in these patients, can also be seen. Patients with abnormal neurologic findings typically have multiple abnormalities on MR imaging, which frequently do not correlate with specific symptoms.     

Diffusion-weighted imaging of white matter abnormalities in patients with phenylketonuria

Phenylketonuria (PKU) is an autosomal recessive disorder caused by a deficiency of the enzyme phenylalanine hydroxylase (EC 1.14.16.1). Affected patients develop elevated plasma and tissue levels of phenylalanine and its related ketoacids. Untreated patients usually exhibit severe mental retardation and poor motor function, with characteristic T2 white matter signal abnormalities on conventional MR images. In the present study, we performed diffusion-weighted imaging in three PKU patients. All three patients demonstrated significantly restricted diffusion in all white matter areas examined.     

Integrated MR imaging and proton nuclear magnetic resonance spectroscopy in a family with an X-linked spastic paraparesis

Seven members of a family with an X-linked spastic paraparesis syndrome were analyzed by MR imaging and stimulated echo, solvent-suppressed proton nuclear magnetic resonance spectroscopy. The MR scans of three symptomatic males and two asymptomatic females demonstrated abnormal signal in the supratentorial white matter. Each of these patients had a proton spectroscopic examination of a 2 X 2 X 2 cm voxel localized to the abnormal white matter of the centrum semiovale. The spectra demonstrated depression of N-acetyl aspartate/creatine, N-acetyl aspartate/choline, and creatine/choline ratios compared with normal control subjects. Additionally, these patients had abnormal elevations of amino acid resonances in the 2.1-3.0 ppm range. In a patient with symmetric white matter signal intensity abnormalities, an asymmetric spectroscopic study correlated with asymmetric symptoms. One asymptomatic family member with a normal MR study had abnormal metabolite ratio measurements. She was referred for further evaluation, since the proton spectrum suggested she may possess the affected gene. If the findings in this study are duplicated in other cases of hereditary dysmyelinating syndromes, we believe the integrated MR/proton nuclear magnetic resonance spectroscopy examination will be of benefit in evaluating and counseling families with familial dysmyelinating disorders.     

MR imaging of periventricular leukomalacia in childhood

Eight children with clinical and radiologic abnormalities consistent with periventricular leukomalacia were investigated with MR imaging of the brain that employed both inversion-recovery and T2-weighted spin-echo imaging sequences. The more precise delineation of white and gray matter on inversion-recovery images as compared with CT allows a detailed demonstration of the anatomic features of periventricular leukomalacia; specifically, a reduced quantity of white matter in the periventricular region and centrum semiovale and, in more severe cases, cavitated infarcts that replace the immediate periventricular white matter. The T2-weighted spin-echo and short inversion time inversion-recovery images demonstrated abnormally increased signal in white matter that appeared normal on CT scans and only minimally abnormal on conventional inversion-recovery images. These abnormalities most probably represent white matter gliosis that extends beyond the immediate periventricular regions. MR recognition of cerebral white matter abnormalities associated with periventricular leukomalacia may confirm the clinical suspicion of this diagnosis in children with spastic diplegia or quadriplegia.     

Migraine: evaluation by MR

Twenty-four patients clinically diagnosed as having migraine (17 of the classic or common type and seven of the complicated type) were evaluated on a 0.5-T or 0.6-T superconductive MR imaging unit with the objective of detecting associated parenchymal lesions. Thirteen (54%) of the patients had normal MR studies. Eleven (46%) of the patients (seven with classic or common and four with complicated migraine) showed well-defined lesions with prolonged T2 signal intensity. The lesions associated with classic migraine were focal and predominantly distributed in the periventricular white matter, bilateral in four and unilateral in three. In the group with complicated migraine, larger cortical abnormalities similar to infarcts were seen in three patients and multiple bilateral focal white matter lesions were seen in one. Almost all the lesions were evident only on T2-weighted studies; a few exhibited hypointense signal intensity on T1-weighted studies. The focal periventricular white matter lesions were not necessarily associated with neurologic deficits, but the cortical lesions were. Our study indicates that parenchymal changes are frequently associated with migraine and that MR may well be the screening and diagnostic method of choice for their detection and evaluation.     

Volumetric brain differences in children with periventricular T2-signal hyperintensities: a grouping by gestational age at birth

OBJECTIVE: The purpose of this study was to compare both the volumes of the lateral ventricles and the cerebral white matter with gestational age at birth of children with periventricular white matter (PVWM) T2-signal hyperintensities on MR images. The spectrum of neuromotor abnormalities associated with these hyperintensities was also determined. MATERIALS AND METHODS: We retrospectively reviewed the MR images of 70 patients who were between the ages of 1 and 5 years and whose images showed PVWM T2-signal hyperintensities. The patients were divided into premature (n = 35 children) and term (n = 35) groups depending on their gestational age at birth. Volumetric analysis was performed on four standardized axial sections using T2-weighted images. Volumes of interest were digitized on the basis of gray-scale densities of signal intensities to define the hemispheric cerebral white matter and lateral ventricles. Age-adjusted comparisons of volumetric measurements between the premature and term groups were performed using analysis of covariance. RESULTS: The volume of the cerebral white matter was smaller in the premature group (54 +/- 2 cm(3)) than in the term group (79 +/- 3 cm(3), p < 0.0001). The volume of the lateral ventricles was greater among the patients in the premature group (30 +/- 2 cm(3)) than among those in the term group (13 +/- 1 cm(3), p < 0.0001). Fifty percent of all the premature children had spastic diplegia or quadriplegia. Thirty-two percent of all the term children had hypotonia. There were patients in both groups whose PVWM T2-signal hyperintensities did not correlate with any neuromotor abnormalities but were associated with seizures or developmental delays. CONCLUSION: The differences in volumetric measurements of cerebral white matter and lateral ventricles in children with PVWM T2-signal hyperintensities are related to their gestational age at birth. Several neurologic motor abnormalities are found in children with such hyperintensities.     

Magnetic resonance imaging of the brain in glutaric acidemia type I: a review of the literature and a report of four new cases with attention to the basal ganglia and imaging technique

RATIONALE AND OBJECTIVES: In glutaric acidemia type I (GA I), a pediatric neurometabolic disease that may be mistaken for nonaccidental trauma, expeditious detection is critical as early treatment may substantially improve psychomotor dysfunction. In this study, we examine in depth the magnetic resonance (MR) findings, with special attention to the basal ganglia, in 4 new cases and compare the findings with those described in the literature. METHODS: MR studies of 4 children, diagnosed to have GA I via cultured fibroblast enzyme studies or urine metabolite assays, were performed on a 1.5 T system in the axial plane using spin echo T(1)-weighted, fast spin echo T(2)-weighted, and fluid-attenuated inversion recovery (FLAIR) technique. Three of 4 patients were followed with serial exams to document temporal evolution of the disease. RESULTS: On T(2)-weighted images, abnormal increased signal intensity was seen in both the putamen and globus pallidus in all cases. However, in contradistinction to cases reported in the literature, involvement of the caudate nucleus was minimal or absent even on serial MR exams. In children 15 months and older, FLAIR improved recognition of basal ganglia and white matter abnormalities. The previously described widened cerebrospinal fluid spaces anterior to the temporal lobes, increased T(2)-weighted signal intensity in the periventricular white matter, and widened sylvian fissures characteristic of GA I were noted in all patients. CONCLUSIONS: Abnormalities of the caudate nucleus are not a prominent presentation of these patients and the absence of this finding should not exclude a diagnosis of GA I. FLAIR scans, as an adjunct to more conventional T(1)- and T(2)-weighted sequences, can play an important role in children 15 months or older despite immature myelination in these patients.     

Magnetic resonance images of tuberous sclerosis

Summary The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.     

Encephalopathy in AIDS patients: evaluation with MR imaging

The presence and extent of encephalopathy were evaluated in 47 patients with AIDS or AIDS-related complex (ARC) by the use of MR imaging. Twenty-nine (62%) of the patients showed some form of white matter disease, exhibited as high signal intensity on T2-weighted images. Focal white matter lesions were seen in 23 (49%) of the patients, while a diffuse white matter process was observed in six patients (13%). Of the 29 patients who had white matter disease on MR scans, 17 (36%) had a suggestion of white matter involvement on an initial CT study. Meanwhile, 12 (26%) of the patients had a normal CT scan on the initial examination. MR findings showed predominant disease in the subinsular and peritrigonal white matter areas. Marked cerebral atrophy was observed in 17 (36%) of 47 patients, cerebellar atrophy in 18 (38%), and brainstem atrophy in seven patients (15%). Pathologic findings showed that toxoplasmosis was present in eight patients (17%), and primary CNS lymphoma was present in three patients (6%). Cryptococcal meningitis was noted in two (4%) of the patients at autopsy, and Mycobacterium tuberculosis was seen in one (2%) of the patients at autopsy. MR imaging has been shown to be a valuable technique for the detection of encephalopathy in AIDS patients.     

Anatomy of the brainstem: correlation of in vitro MR images with histologic sections

MR imaging was performed on three formaldehyde-fixed brainstem specimens that were sectioned in the axial plane and myelin stained. The histologic sections were used to identify and label the structures demonstrated on short TR/TE axial MR images. Fiber tracts and nuclei that cannot be resolved on in vivo scans were well delineated by in vitro MR. Improved gray-white differentiation may be due to much greater T1 shortening of gray matter relative to white matter after fixation. The excellent anatomic detail provided by these scans should facilitate comparison of clinical scans with histologic sections.     

Orbital and optic pathway sarcoidosis: MR findings.

PURPOSETo identify and characterize the MR findings of sarcoidosis when it involves the orbit and visual pathways.METHODSThe MR scans of 15 patients, 3 with presumed and 12 with proved orbital or optic pathway sarcoidosis were retrospectively reviewed.RESULTSEight patients had MR evidence of optic nerve involvement by sarcoid granuloma. Perineural enhancement was seen in four cases, optic atrophy in one. Three who had had unenhanced scans showed optic nerve enlargement. Nine patients had optic chiasmal involvement. One patient had increased T2 signal in the optic radiations. Three patients had orbital masses that had MR signal characteristics similar to pseudotumor. Five patients had periventricular white matter abnormalities closely resembling multiple sclerosis.CONCLUSIONSSarcoidosis should be considered in the differential diagnosis of optic nerve or nerve sheath enhancement on MR. Orbital sarcoidosis has MR characteristics very similar to pseudotumor.     

MR and CT of tuberous sclerosis: linear abnormalities in the cerebral white matter

A review of MR and CT images in five patients, 8 months to 22 years old, diagnosed as having tuberous sclerosis, revealed linear abnormalities in the cerebral white matter. A linear abnormality connecting a subependymal nodule to a subcortical lesion was shown in two patients as an area of hypointensity on T1-weighted MR images and as an area of hyperintensity on T2-weighted images. These appeared as faintly high-density areas on CT images. Seventeen linear abnormalities extending from the ventricle to the cortex with a subependymal nodule or subcortical lesion on each end were visible in all five patients as areas of hyperintensity on the T2-weighted images. On the T1-weighted images, only nine hypointense lines were noted. CT scans did not show these latter lines. Linear abnormalities in cerebral white matter are suggestive of lesions of demyelination, dysmyelination, hypomyelination, or lines of migration disorder. MR imaging, especially T2-weighted, is particularly sensitive in detecting these abnormalities.     

MR imaging of phenylketonuria

Cranial MR imaging was performed on nine patients (13-27 years old) with classical phenylketonuria in order to define the spectrum of abnormal findings and to determine if these could be related to clinical or biochemical findings. MR abnormalities consistent with demyelination were found in varying degrees in a distribution corresponding to previous histopathologic studies. Specifically, increased signal was seen on T2-weighted sequences, most marked in the periventricular deep cerebral white matter. These changes were more prominent posteriorly, especially about the optic radiations. Comparison with clinical history and MR findings in this small series revealed that patients with adequate dietary control of phenylalanine levels had less severe white matter abnormalities than did patients with poorly controlled phenylalanine intake.     

Corpus callosal signal changes in patients with obstructive hydrocephalus after ventriculoperitoneal shunting

BACKGROUND AND PURPOSE: Few reports have documented signal abnormalities within the corpus callosum on MR studies obtained after ventricular decompression in patients with hydrocephalus. Our purpose was to establish the frequency of this finding in shunted patients and attempt to elucidate its cause and clinical significance. METHODS: All patients with hydrocephalus shunted between 1989 and 1999 with postoperative MR studies available for review were included in the study group. Imaging analysis consisted of documenting hypointense signal on T1-weighted sagittal images and hyperintense signal on double-echo T2-weighted axial images within the corpus callosum. RESULTS: Characteristic signal abnormalities in the corpus callosum were noted in nine of 161 patients with shunted hydrocephalus studied with MR imaging. All nine patients were asymptomatic in regard to these MR findings. Comparison with preoperative scans and surgical records revealed that all patients with signal changes on postshunt scans had chronic obstructive hydrocephalus at presentation. Preshunt MR images were notable for marked elevation of the corpus callosum, which subsequently descended after ventricular decompression, suggesting that the cause of the signal changes was related to compression of the corpus callosum against the rigid falx. CONCLUSION: Signal abnormalities within the corpus callosum after ventricular shunting for obstructive hydrocephalus are not uncommon and are probably produced by compression of the corpus callosum against the falx before ventricular decompression. This distinctive appearance should not be mistaken for significant disease. Recognition of this pattern of signal abnormality will help avoid unnecessary intervention.     

West Nile virus infection: MR imaging findings in the nervous system

BACKGROUND AND PURPOSE: West Nile virus (WNV) infection is an ongoing seasonal epidemic. We correlated the MR imaging findings with the clinical presentations and outcomes of WNV infection. METHODS: We reviewed 14 brain and three spinal MR images: nonenhanced and contrast-enhanced T1-weighted images (T1WIs) and T2-weighted images (T2WIs), nonenhanced fluid-attenuated inversion recovery (FLAIR) images (11 patients) and enhanced FLAIR images (three patients), with diffusion-weighted (DW) images and apparent diffusion coefficient maps. WNV infection was diagnosed by means of enzyme-linked immunosorbent assay with a plaque reduction neutralization test. We also correlated the MR findings with the clinical presentation, course, and outcome to determine their prognostic importance. RESULTS: MR imaging findings included: 1) normal (five patients); 2) DW imaging-only abnormalities in the white matter, corona radiata, and internal capsule (four patients); 3) hyperintensity on FLAIR images and T2WIs in the lobar gray and white matter, cerebellum, basal ganglia, thalamus and internal capsule, pons and midbrain (three patients); 4) meningeal involvement (two patients); and 5) spinal cord, cauda equina, and nerve root involvement (three patients). All patients with finding 1 and all but one with finding 2 recovered completely. Two patients with finding 3 died. Those with finding 4 or 5 had residual neurologic deficits that were severe or moderate to severe, respectively. CONCLUSION: Patients with normal MR images or abnormalities on only DW images had the best prognosis, while those with abnormal signal intensity on T2WI and FLAIR images had the worst outcomes. No definite predilection for any specific area of the brain parenchyma was noted.     

Brain MR in chronic fatigue syndrome.

PURPOSETo determine the prevalence of MR white matter abnormalities in patients with chronic fatigue syndrome (CFS).METHODSBrain MR studies of 43 patients (29 women and 14 men, 22 to 78 years old) with a clinical diagnosis of CFS (n = 15), CFS with associated depression (n = 14), and CFS with associated other psychiatric disorders, namely, anxiety and somatization disorder (n = 14), were compared with brain MR studies in 43 age- and sex-matched control subjects.RESULTSMR findings were abnormal in 13 (32%) of the patients in the study group (ages 34 to 78 years) and in 12 (28%) of the control subjects (ages 26 to 73 years). One patient with CFS had multiple areas of demyelination in the supratentorial periventricular white matter. Another patient with CFS and associated depression had a single focus of probable demyelination in the supratentorial periventricular white matter. In four patients with CFS (ages 34 to 48 years) MR abnormalities consisted of one or several punctate hyperintense foci in the corona radiata, centrum ovale, and frontal white matter. The remaining seven patients (ages 50 to 78 years) had frontoparietal subcortical white matter foci of high T2 signal. The prevalence of white matter hyperintensities was not different between the patients and the control subjects.CONCLUSIONSOur findings suggest that no MR pattern of white matter abnormalities is specific to CFS.     

Quantitative MR in the diagnosis of multiple sclerosis.

In patients with multiple sclerosis (MS), the apparently uninvolved cerebral white matter between demyelinated plaques may have biochemical abnormalities. To what degree the changes in the white matter contribute to symptomatology in MS is unknown. In 39 patients with multiple sclerosis, and in 39 age-matched nondiseased volunteers, T1 and T2 were calculated from spin-echo images in four regions of apparently uninvolved white matter. In three of four white matter areas, the average T1 and T2 were significantly longer in the patients than in the controls. The T1 correlated with the disability, measured by the Kurtzke Extended Disability Status Scale, although the correlation was marginally significant. The results suggest that in patients with MS, white matter disease that is not visualized in MR as distinct foci of abnormal signal intensity may contribute to disease burden and disability.