(18)F-fluorodeoxyglucose positron emission tomography and MR imaging findings in Rasmussen encephalitis

BACKGROUND AND PURPOSE: Rasmussen encephalitis is a chronic, progressive encephalitis that manifests as an abrupt-onset, intractable seizure disorder in previously developmentally normal children. The objectives of the current study were to characterize the (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and MR imaging findings in Rasmussen encephalitis and to test the hypotheses that data from both imaging techniques are required to establish the diagnosis and identify the affected cerebral hemisphere in some cases. METHODS: Eleven patients with Rasmussen encephalitis were identified from a review of a computer database. The MR (n = 10) and PET (n = 11) imaging data were reviewed retrospectively and conjointly. RESULTS: On MR images, nine of 10 patients manifested bilateral cerebral atrophy that predominantly involved one hemisphere. One patient had purely unilateral cerebral atrophy. We observed foci of abnormally increased T2 signal intensity in nine of 10 patients. On FDG PET images, all patients showed extensive regions of hypometabolism within the cerebral hemisphere that showed the greatest atrophy. Discrete foci of hypermetabolism, indicative of seizure activity, were observed in six patients. The FDG PET and MR imaging findings were either stable or gradually progressive in patients with multiple imaging studies (MR, n = 5; FDG PET, n = 5). CONCLUSION: Rasmussen encephalitis is characterized by diffuse, unilateral cerebral hypometabolism on FDG PET images, with corresponding regions of cerebral atrophy on MR images. Although MR imaging data alone are sufficient to suggest a diagnosis of Rasmussen encephalitis in many cases, correlation with FDG PET data increases diagnostic confidence and allows the unequivocal identification of the affected cerebral hemisphere in patients whose MR imaging findings are subtle or distributed bilaterally.     

Brain involvement in Salla disease

BACKGROUND AND PURPOSE: Our purpose was to document the nature and progression of brain abnormalities in Salla disease, a lysosomal storage disorder, with MR imaging. METHODS: Fifteen patients aged 1 month to 43 years underwent 26 brain MR examinations. In 10 examinations, signal intensity was measured and compared with that of healthy volunteers of comparable ages. RESULTS: MR images of a 1-month-old asymptomatic child showed no pathology. In all other patients, abnormal signal intensity was found: on T2-weighted images, the cerebral white matter had a higher signal intensity than the gray matter, except in the internal capsules. In six patients, the white matter was homogeneous on all images. In four patients, the periventricular white matter showed a somewhat lower signal intensity; in five patients, a higher signal intensity. In the peripheral cerebral white matter, the measured signal intensity remained at a high level throughout life. No abnormalities were seen in the cerebellar white matter. Atrophic changes, if present, were relatively mild but were found even in the cerebellum and brain stem. The corpus callosum was always thin. CONCLUSION: In Salla disease, the cerebral myelination process is defective. In some patients, a centrifugally progressive destructive process is also seen in the cerebral white matter. Better myelination in seen in patients with milder clinical symptoms.     

Comparison of CT and MR features with clinical outcome in patients with Rocky Mountain spotted fever.

PURPOSETo compare neuroimaging findings and clinical features in patients with Rocky Mountain spotted fever and to determine the impact of imaging studies in the treatment of these patients.MATERIALSWe reviewed the brain CT scans (n = 44), MR images (n = 6), or both (n = 4), and one MR spinal study in 34 patients with Rocky Mountain spotted fever, proved by definitive serologic criteria. Records were reviewed with attention to clinical symptoms and therapeutic modifications based on neuroimaging; outcomes were compared with imaging findings.RESULTSAbnormalities, consisting of infarctions, cerebral edema, meningeal enhancement, and prominent perivascular spaces, were found on four of 44 CT scans and on four of six MR studies. The spinal MR study showed abnormal enhancement of the lower spinal cord and cauda equina. Nonspecific clinical symptoms were present in all patients in whom neuroimaging findings were abnormal and in 80% of patients whose CT and/or MR findings were normal. After treatment, return to baseline clinical status was documented in 67% of patients with abnormal imaging findings and in 93% with normal findings. Death occurred in 17% of patients with abnormal neuroimaging results and in none of those with normal results.CONCLUSIONSAbnormalities on neuroimaging studies were not common in patients with Rocky Mountain spotted fever. When present, they were subtle. Symptoms at presentation and unfavorable outcomes were more prevalent when CT or MR findings were abnormal. Abnormalities identified on neuroimaging studies did not alter clinical treatment in any patient.     

The congenital bilateral perisylvian syndrome: imaging findings in a multicenter study. CBPS Study Group.

PURPOSETo describe the neuroimaging findings and the clinical features in patients with the congenital bilateral perisylvian syndrome.PATIENTS AND METHODSEvaluation including history, general and neurologic examinations, electroencephalogram, chromosomal studies, and imaging data were reviewed in 31 patients. Pathologic material was available in two patients.RESULTSAll patients had similar neurologic dysfunction, primarily pseudobulbar paresis. Dysarthria and severe restriction of tongue movements were present in all. Motor milestones were delayed in 75% of the patients and language milestones in all. Mild to moderate intellectual deficits were documented in 75% of patients (full-scale IQ = 70). Pyramidal signs were observed in 70%. Seizures were present in 87% and were intractable to medical therapy in half of this group. MR revealed bilateral perisylvian and perirolandic malformations with exposure of the insula. The malformations were symmetrical in 80% of cases. Pathologic correlation revealed four layered polymicrogyria in the affected areas.CONCLUSIONSThe congenital bilateral perisylvian syndrome is a homogeneous clinical-radiologic entity. The underlying abnormality is probably polymicrogyria.     

Radiologic and neuropathologic findings in patients in a family with dentatorubral-pallidoluysian atrophy

We describe the cases of 2 patients, a father and his son, with DRPLA who underwent MR examinations prior to death and in whom postmortem examinations of the brain were obtained. MR imaging findings had the following features: 1) atrophy of the cerebellum and brain stem were the common findings, 2) high-signal-intensity lesions in the cerebral white matter and brain stem were observed on T2-weighted images in the patient with adult-onset DRPLA, 3) signal-intensity changes in the cerebral white matter were restricted to the periventricular white matter in the patient with juvenile-onset DRPLA, but these changes appear in the advanced stage, and 4) progressive cerebral atrophy was more marked in the patient with juvenile-onset DRPLA. In the patients with DRPLA, the abnormal high signal intensity of the cerebral white matter or brain stem on MR images reflect the loss of myelinated fibers. Cerebral atrophy mainly reflects atrophy of the neuropile.     

Clinical,neurodiagnostic, and MR findings in children with spinal and brain stem multiple sclerosis.

PURPOSETo describe the clinical, neurodiagnostic, and MR findings in seven children with brain stem and spinal multiple sclerosis.METHODSSpinal or brain stem multiple sclerosis was diagnosed in seven children between 1986 and 1992. All patients had neurologic and MR examinations as well as neurodiagnostic testing, including spinal fluid analysis and brain stem and auditory evoked potentials.RESULTSThree children had clinical findings and masslike lesions in the brain stem (two) or spinal cord (one) suggestive of neoplasm, which prompted biopsy (two) or radiation therapy (one). Five of six patients with spinal involvement had cord swelling with increased signal on T2-weighted images over at least three cord segments, and two children had essentially holocord involvement. Three children had normal cranial MR at presentation.CONCLUSIONSMultiple sclerosis involvement of the brain stem and spinal cord may be associated with extensive swelling and MR signal changes suggestive of neoplasm without typical cerebral white matter abnormalities. Serial clinical and neuroimaging examinations may be necessary to make a definitive diagnosis of multiple sclerosis in children.     

Neuroradiologic findings in children with mitochondrial disorders.

PURPOSEWe report the neuroradiologic findings in 25 children with various mitochondrial diseases.METHODSTwenty-two children with a mitochondrial disorder had MR imaging of the brain and three children had CT studies. In all cases, the diagnosis was based on examination of muscle morphology, analysis of oxygen consumption and respiratory chain enzyme activity in isolated muscle mitochondria, and analysis of rearrangements of the mitochondrial DNA.RESULTSFifteen patients were found to have the classical syndromes of mitochondrial diseases. Four children had Kearns-Sayre syndrome, but only one had the typical neuroradiologic findings of basal ganglia and brain stem lesions, T2 hyperintensity of the cerebral white matter, and cerebellar atrophy; the others had nonspecific or normal findings. Eight patients had Leigh syndrome, and all showed changes in the putamina. Involvement of the caudate nuclei, globus pallidi, thalami, and brain stem was common, and diffuse supratentorial white matter T2 hyperintensity was seen in two of these patients. Three patients had mitochondrial encephalopathy with lactic acidosis and strokelike episodes (MELAS), with infarctlike lesions that did not correspond to the vascular territories. Ten children with complex I or IV deficiencies and abnormal muscle morphology had nonspecific imaging findings, such as atrophy and abnormal or delayed myelination. One patient with combined complex I and IV deficiency had extensive white matter changes. None of the patients with clinical encephalopathy had normal findings.CONCLUSIONMR imaging is helpful in the diagnosis of the classical mitochondrial diseases; however, nonspecific findings are common.     

Congenital porencephaly: MR features and relationship to hippocampal sclerosis.

PURPOSEWe determined the frequency of amygdalar-hippocampal atrophy in patients with congenital porencephaly-related seizure disorders to ascertain whether specific MR features of the porencephaly correlate with amygdalar-hippocampal atrophy and epilepsy.METHODSWe studied brain MR images of 22 patients with congenital porencephaly and measured the volume of the amygdala, the hippocampal formation, and the porencephalic cyst. We then compared imaging features with seizure symptoms.RESULTSPorencephaly was unilateral in 20 patients and bilateral in two. Eighteen patients had cortical or subcortical cavitation and four had encephaloclastic changes (noncircumscribed parenchymal destruction associated with cystic components). The porencephaly was located in the middle cerebral artery territory in 12 patients, in the posterior cerebral artery in four, in the internal carotid artery in two, and in multiple vessels in four. The volume of the porencephalic cyst ranged from 1% to 32% of total intracranial volume (mean, 11%). Volumetry detected atrophy of the hippocampal formation in 21 cases (11 unilateral, 10 bilateral) and atrophy of the amygdala in 12 (nine unilateral, three bilateral). No correlation was found between size or location of the porencephaly and degree of hippocampal atrophy. Seizure symptoms correlated with mesial temporal origin but not with cyst location.CONCLUSIONAmygdalar-hippocampal atrophy often coexists with congenital porencephaly (95%), and the atrophy may be bilateral despite unilateral cysts. Hippocampal structures should be carefully assessed in patients with porencephaly-related seizures.     

CT and MR characteristics of cerebral sparganosis

BACKGROUND AND PURPOSE: Sparganosis is a rare parasitic infection in humans by a larval cestode of the genus Spirometra. Preoperative diagnosis of cerebral sparganosis in the past has been very difficult. Our objective was to evaluate the CT and MR features of cerebral sparganosis in order to make a definite diagnosis. MATERIALS AND METHODS: We retrospectively reviewed 25 patients (13 male and 12 female; age range, 9-83 years) who proved to have cerebral sparganosis. Fifteen patients underwent MR imaging: 2 patients had CT scanning, and the remaining 8 had both CT and MR scanning. We focused on evaluating the imaging features on CT and MR. RESULTS: All patients showed edema and degeneration of cerebral white matter. All but 1 had a unilateral lesion. Twenty-two patients had ipsilateral ventricular dilation. The new finding was a tunnel sign, approximately 4 cm in length and 0.8 cm in width, column or fusiform shaped on postcontrast coronal and sagittal MR images (n = 10). Thirteen patients showed bead-like enhancement, but solitary ring enhancement was common on the CT images (n = 2). The wall of the ring and tunnel appeared isointense or slightly hyperintense on T2-weighted images. Punctate calcifications were seen in 6 patients on CT images but only in 3 patients on the MR images. Hemorrhage was seen in 4 patients on the MR images. An intact whitish, stringlike, living worm was found (n = 5). CONCLUSION: The most characteristic finding was a tunnel sign on postcontrast MR images. The most common finding was bead-shaped enhancement. MR is superior to CT in demonstrating the extent and number of lesions, except punctate calcifications. Combined with clinical data and enzyme-linked immunosorbent assay, the preoperative diagnosis of cerebral sparganosis could be established on MR imaging.     

New syndrome characterized by hypomyelination with atrophy of the basal ganglia and cerebellum

BACKGROUND AND PURPOSE: Leukoencephalopathies of unknown origin constitute a considerable problem in child neurology. The purpose of our ongoing study of the subject was to define new disease entities among them by using primarily MR imaging pattern recognition. METHODS: We identified seven unrelated patients with a distinct MR imaging pattern consisting of hypomyelination and atrophy of the basal ganglia (neostriatum) and cerebellum (H-ABC). We reviewed the clinical, MR imaging, MR spectroscopic, and laboratory data. RESULTS: Clinically, the patients' diseases were characterized by variably disturbed early development followed by increasing extrapyramidal movement abnormalities, ataxia, and spasticity. Mental capacity was variably affected, but it appeared to be relatively preserved. Parents were not related, and none of their siblings were affected. No metabolic defect was found. Follow-up MR imaging demonstrated atrophy of the cerebral white matter, neostriatum, and cerebellum, which was most pronounced in the most clinically severe cases. Single-voxel proton MR spectroscopic results were normal in the parietal cortex. In the cerebral white matter, myo-inositol and creatine levels were elevated; this finding was compatible with gliosis. N-acetylaspartate and choline levels were normal, suggesting that neither axonal loss nor active demyelination occurred. Proton MR spectroscopic imaging revealed relatively decreased N-acetylaspartate levels in the frontal region. CONCLUSION: The uniform and highly characteristic MR imaging findings, in combination with the similarities in the clinical findings, provide evidence of a distinct nosologic entity. The acronym H-ABC is offered to indicate patients sharing these clinical and MR imaging features.     

Phenylketonuria: MR imaging of the brain with clinical correlation

Fifteen patients with biochemically documented phenylketonuria (PKU) were studied with use of magnetic resonance (MR) imaging with spin-echo T2-weighted pulse sequences. The resulting images demonstrated varying degrees of symmetric high signal intensity of the white matter within the posterior cerebral hemispheres. Involvement of the anterior hemispheres was seen only in cases with severe signal intensity changes. There was no involvement of the cerebral cortex, brain stem, or cerebellum. Moreover, no anatomic structural abnormalities were observed. Mild cortical atrophy was observed in eight of the 15 patients. There was no significant correlation between the patients' IQ scores and the level of MR signal intensity changes. Although MR imaging routinely shows relatively distinct abnormalities in patients with PKU, the clinical severity of the disease does not parallel its imaging severity.     

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.     

The Sturge-Weber syndrome: comparison of MR and CT characteristics

Four patients with Sturge-Weber syndrome were evaluated with CT and MR. MR demonstrated the characteristic features of the disease: cerebral atrophy (four patients), ipsilateral bone and sinus hypertrophy (three), ocular findings (one), intracranial calcification (four), prominent deep venous system (three), and enlarged choroid plexus (two). CT demonstrated the following: cerebral atrophy (four), ipsilateral bone and sinus hypertrophy (three), calcification (four), gyral enhancement (two), prominent deep venous system (two), and enlarged choroid plexuses (three). The features of Sturge-Weber syndrome were visualized equally well with MR and CT with the exception of intracranial calcification. Conventional spin-echo MR revealed fewer calcifications, and those visualized appeared smaller than with CT. Gradient-echo acquisition sequences were more effective in the detection of intracranial calcification.     

Disorders of cortical formation: MR imaging features

The purpose of this article was to review the embryologic stages of the cerebral cortex, illustrate the classification of disorders of cortical formation, and finally describe the main MR imaging features of these disorders. Disorders of cortical formation are classified according to the embryologic stage of the cerebral cortex at which the abnormality occurred. MR imaging shows diminished cortical thickness and sulcation in microcephaly, enlarged dysplastic cortex in hemimegalencephaly, and ipsilateral focal cortical thickening with radial hyperintense bands in focal cortical dysplasia. MR imaging detects smooth brain in classic lissencephaly, the nodular cortex with cobblestone cortex with congenital muscular dystrophy, and the ectopic position of the gray matter with heterotopias. MR imaging can detect polymicrogyria and related syndromes as well as the types of schizencephaly. We concluded that MR imaging is essential to demonstrate the morphology, distribution, and extent of different disorders of cortical formation as well as the associated anomalies and related syndromes.     

Cerebrotendinous xanthomatosis (van Bogaert-Scherer-Epstein disease): CT and MR findings.

PURPOSETo describe the CT and MR findings in the brain and spinal cord of patients with cerebrotendinous xanthomatosis and to seek possible correlations between clinical, biochemical (cholestanol levels), and neuroimaging findings.METHODSTen patients with well-defined clinical and biochemical diagnoses of cerebrotendinous xanthomatosis were examined. Brain CT was performed in eight cases. In all patients MR was obtained using spin-echo and gradient-echo sequences. In eight patients spine MR was also performed.RESULTSNeuroradiologic findings included diffuse cerebral and cerebellar atrophy. In half the cases, atrophy of the brain stem and corpus callosum was also found. In the majority of patients cerebellar bilateral focal lesions and mild white matter signal alterations were present. Spinal cord MR did not show signal abnormalities or atrophy.CONCLUSIONSWe found cranial alterations in patients with severe neurologic impairment, but there was no correlation with cholestanol plasma levels. No spinal cord abnormalities were present.     

Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging

The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio.     

Ipsilateral mamillary body atrophy after infarction of the posterior cerebral artery territory: MR imaging

We describe herein magnetic resonance (MR) features of ipsilateral mamillary body atrophy after infarction of the posterior cerebral artery (PCA) territory. During the period May 2000 through July 2004, 13 patients with infarction of the PCA territory underwent cranial MR imaging in the chronic stage. Two 1.5-T scanners were used to obtain axial T1- and T2-weighted images with conventional spin-echo and fast spin-echo pulse sequences, respectively. The slice thickness was 6 mm, with a 2-mm interslice gap. Five of the 13 patients with PCA territory infarction had ipsilateral mamillary body atrophy. However, this asymmetry of the mamillary bodies was unclear in two of the five patients because of the thickness of the axial image slices. All five patients had a temporo–parieto–occipital infarction. The remaining eight patients had a parieto–occipital or an occipital infarction. Unilateral transneuronal mamillary body degeneration after infarction of the ipsilateral PCA territory including the posteromedial temporal lobe can be detected on conventional thick axial MR images.     

Neuroradiological findings in primary progressive aphasia: CT,MRI and cerebral perfusion SPECT

Primary progressive aphasia (PPA) is defined as progressive decline in language for 2 or more years with preservation of activities of daily living and general cognitive functions. Whereas the clinical features of this syndrome have been well documented, the neuroradiological findings have not been studied systematically. We studied 13 patients with PPA retrospectively: 10 underwent CT, 12 MRI and 12 cerebral perfusion studies using^99mTc-HMPAO SPECT. CT and MR images were scored for focal atrophy by two independent assessors. Initial qualitative assessment of SPECT images was confirmed by quantitative analysis. CT was normal in 5 patients. Focal atrophy, affecting predominantly the left temporal lobe, was seen in 4 of 10 patients on CT, and 10 of 12 on MRI. Atrophy was localised primarily to the superior and middle temporal gyri on MRI. All 12 patients who underwent SPECT had unilateral temporal lobe perfusion defects, in 2 patients of whom MRI was normal. CT is relatively insensitive to focal abnormalities in PPA; MRI and SPECT are the imaging modalities of choice. MRI allows accurate, specific localisation of atrophy within the temporal neocortex. SPECT may reveal a functional decrease in cerebral perfusion prior to establishment of structural change.     

MR of craniocerebral hemiatrophy.

The magnetic resonance (MR) findings of three patients with cerebral hemiatrophy, the so-called Dyke-Davidoff-Masson syndrome, which is characterized by variable degrees of unilateral loss of cerebral volume and compensatory changes of the calvarium are presented. The condition was due to middle cerebral artery stroke in all patients. The pathologic alterations of cerebral tissue and the brainstem were reflected in detail on the MR studies. MR findings in addition to the primary vascular insult included prominence of the cortical sulci and perimesencephalic cistern in one subject with acquired infarction, but an absence of such generalized sulcal prominence in two cases of congenital infantile paralysis. Otherwise the secondary ipsilateral pathologic observations were quite similar in the patients with congenital and acquired ischemic disease and encompassed a unilaterally small cerebral hemisphere together with ipsilateral diploic calvarial expansion, elevation of the petrous bone and orbital roof, and hypoplasia/atrophy of the cerebral peduncle. Although computed tomography (CT) and MR are complimentary, it is felt that MR represents the imaging procedure of choice with respect to the assessment of the etiology and extent of cerebral parenchymal involvement in patients presenting with a clinical combination of congenital or early onset of seizures, hemiparesis/plegia, and/or craniofacial asymmetry.     

Neuroradiologic findings in children with mitochondrial disorder: correlation with mitochondrial respiratory chain defects

Mitochondrial disorders are a heterogeneous group of disorders affecting energy metabolism that can present at any age with a wide variety of clinical symptoms. We investigated brain magnetic resonance (MR) findings in 40 children with defects of the mitochondrial respiratory chain (MRC) complex and correlated them with the type of MRC defects. Enrolled were 40 children with MRC defects in biochemical enzyme assay of the muscle specimen. Twenty-one children were found to have classical syndromes of mitochondrial disorders and 19 children presented nonspecific mitochondrial encephalomyopathies. Their brain MR imaging findings were retrospectively reviewed and correlated with the biochemical defect in the MRC complex. Children with MRC defects showed various neuroradiologic features on brain MR imaging that resulted from a complex genetic background and a heterogeneous phenotype. Rapid progression of atrophy involving all structures of the brain with variable involvement of deep gray and white matter are the most frequent MR findings in children with MRC defects in both classical syndromes of mitochondrial disorder and nonspecific mitochondrial encephalomyopathies. The type of biochemical defect in the MRC complex enzyme did not correlate with brain MR findings in child patients.