How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors?

BACKGROUND: Supratentorial atypical teratoid rhabdoid tumor (ATRT) in many cases has a distinctive appearance on post-gadolinium MRI. OBJECTIVE: We sought to determine whether this is a unique appearance allowing ATRT to be distinguished accurately from other types of pediatric supratentorial tumors. MATERIALS AND METHODS: Retrospective review of all available preoperative MRI of pediatric supratentorial tumors at two tertiary children's hospitals, and systematic literature review of case series and reports describing the MRI imaging appearances of supratentorial ATRT. RESULTS: We had 61 supratentorial tumors, including 32 gliomas, 6 ATRT, 8 ependymomas, 6 gangliogliomas, 2 pilomyxoid astrocytomas, 3 primitive neuro-ectodermal tumors, 2 choroid plexus papillomas, and 2 meningiomas. ATRT presented in significantly younger patients than astrocytomas (mean age 2.6 years vs. 9.9 years, P < 0.05). The visual pattern of a thick, wavy (irregular) heterogeneously enhancing wall around a cystic center was seen in 5/6 (83%) ATRTs and only 3/55 (5.4%) other tumors (P < 0.0001), for specificity of 95%, sensitivity of 83%, positive predictive value of 63% and a negative predictive value of 95%. CONCLUSION: A supratentorial tumor with a thick, wavy (irregular) heterogeneously enhancing wall surrounding a central cystic region is suggestive of ATRT in the appropriate clinical setting, especially in a child of preschool age.

Acute transverse myelitis and acute disseminated encephalomyelitis in childhood: spectrum or separate entities?

The clinical and radiological features of childhood acute transverse myelitis are compared to those of acute disseminated encephalomyelitis with spinal cord involvement in 22 children with acute transverse myelitis and 12 children with acute disseminated encephalomyelitis with spinal cord involvement. Children with acute transverse myelitis were more likely to have a sensory level (55%) and areflexia. Sixty-eight percent of the children with acute transverse myelitis, and 92% of children with acute disseminated encephalomyelitis had longitudinally extensive transverse myelitis. Demyelination was more extensive in acute disseminated encephalomyelitis (mean 15.6 vertebral segments) than in acute transverse myelitis (mean 8.0 vertebral segments). The outcome was normal to good in 82% with acute transverse myelitis and in 100% with acute disseminated encephalomyelitis. Persistent bladder dysfunction was uncommon in both. Poor prognostic factors in acute transverse myelitis are flaccid paraparesis, respiratory failure, and age less than 6 months. These clinical and radiological differences suggest acute transverse myelitis and acute disseminated encephalomyelitis are separate entities.

Temozolomide in pediatric low-grade glioma.

BACKGROUND: We describe a retrospective series of children with low-grade glioma who received temozolomide. PROCEDURE: Eligible patients had had a diagnosis of low-grade glioma with or without histological confirmation. Temozolomide was administered at a dose of 200 mg/m(2) daily for 5 days, in a 4-week cycle. Therapy was stopped on completion of the targeted 12 cycles of chemotherapy or on evidence of tumor progression. RESULTS: Thirteen eligible patients were identified, eight male and five female. Median age at diagnosis was 5.5 years (range 2.6-15.0 years) and at commencement of temozolomide treatment was 9.0 years (range 3.8-15.2 years). Nine patients had a histological diagnosis of pilocytic astrocytoma. Twelve patients had received carboplatin prior to temozolomide, including three in combination with vincristine. A total of 111 cycles of therapy have been administered. Hematological toxicity and nausea were the most common adverse effects. Median time to progression was 6.7 months (range 1.5-41.8 months). Event-free survival rate at 3 years was 57%. Twelve of 13 patients remain alive at the time of report. Eleven have stable disease (SD). CONCLUSION: Temozolomide appears to be active in pediatric low-grade glioma, with the advantage of oral administration and excellent tolerability.

Apparent diffusion coefficient in the posterior limb of the internal capsule predicts outcome after perinatal asphyxia.

OBJECTIVE: Predicting long-term outcome in infants with hypoxic-ischemic encephalopathy (HIE) is a difficult task. Magnetic resonance imaging, particularly diffusion imaging, holds promise in this regard as it is more sensitive to brain injury than any other available imaging modality. Previous studies have suggested that abnormal signal intensity in the posterior limb of the internal capsule (PLIC), detectable on inversion-recovery T1-weighted imaging, is a strong predictor of outcome. The aim of this study was to assess the relationship between apparent diffusion coefficient (ADC) values from the PLIC, measured by diffusion imaging, and neuromotor outcome in term infants with HIE. METHODS: Twenty-eight term infants with a clinical diagnosis of HIE underwent magnetic resonance imaging as soon as practicable after birth (mean age: 5.6 days), including diffusion-weighted imaging, from which ADC values in the PLIC were measured. Motor outcome was assessed in 12 of 16 survivors. RESULTS: The ADC value in the PLIC was significantly associated with survival in term infants with HIE. For survivors, the mean ADC value in the PLIC was 0.89 +/- 0.17 microm2/ms, whereas the mean ADC value for nonsurvivors was 0.75 +/- 0.17 microm2/ms (t = 2.25). Among survivors, the ADC value in the PLIC was also associated with neuromotor outcome (F = 5.60). CONCLUSION: The ADC value in the PLIC is an indicator of ischemic injury and may be of use as an objective prognostic marker for infants with HIE.

MR imaging and spectroscopic study of epileptogenic hypothalamic hamartomas: analysis of 72 cases.

BACKGROUND AND PURPOSE: Reports of MR imaging in hypothalamic hamartomas associated with epilepsy are few, and the number of patients studied is small. We aimed to detail the relationship of hypothalamic hamartomas to surrounding structures, to determine the frequency and nature of associated abnormalities, and to gain insight into mechanisms of epileptogenesis. METHODS: We systematically examined MR imaging studies of 72 patients with hypothalamic hamartoma and refractory epilepsy (patient age, 22 months to 31 years). A dedicated imaging protocol was used in 38 cases. Proton MR spectroscopy of the hypothalamic hamartoma was performed for 19 patients and compared with the metabolite profile of the thalamus in 10 normal children and the frontal lobe in 10 normal adults. RESULTS: Compared with normal gray matter, hypothalamic hamartomas were hyperintense on T2-weighted images (93%), hypointense on T1-weighted images (74%), and had reduced N-acetylaspartate and increased myoinositol content shown by MR spectroscopy. Hypothalamic hamartomas always involved the mammillary region of the hypothalamus, with attachment to one or both mammillary bodies. Intrahypothalamic extension (noted in 97%) tended to displace the postcommissural fornix and hypothalamic gray matter anterolaterally, such that the hypothalamic hamartomas nestled between the fornix, the mammillary body, and the mammillothalamic tract. Larger hamartoma size was associated with central precocious puberty. Associated findings of questionable epileptic significance included anterior temporal white matter signal intensity abnormalities (16%) and arachnoid cysts (6%). Malformations of cortical development were observed in only two patients, and hippocampal sclerosis was not observed. CONCLUSIONS: Hypothalamic hamartomas can be readily distinguished from normal hypothalamic gray and adjacent myelinated fiber tracts, best appreciated on thin T2-weighted images. MR imaging and spectroscopy suggest reduced neuronal density and relative gliosis compared with normal gray matter. Associated epileptogenic lesions are rare, supporting the view that the hypothalamic hamartoma alone is responsible for the typical clinical features of the syndrome. The intimate relationship to the mammillary body, fornix, and mammillothalamic tract suggests a role for these structures in epileptogenesis associated with hypothalamic hamartomas.

Anterior temporal changes on MR images of children with hippocampal sclerosis: an effect of seizures on the immature brain?

BACKGROUND AND PURPOSE: Ipsilateral loss of anterior temporal gray-white matter definition, due mainly to white matter signal intensity abnormality, is frequently seen on MR images of patients with hippocampal sclerosis. Our aim was to determine the prevalence and clinical correlations of these anterior temporal changes in pediatric cases of hippocampal sclerosis and to determine whether cumulative damage from seizures is important for their development. METHODS: We reviewed the MR images and clinical details of 54 children (age range, 1.5-19 years) with typical hippocampal sclerosis. Specific imaging features noted included hippocampal sclerosis, anterior temporal changes, anterior temporal atrophy, and extra-hippocampal abnormality. RESULTS: Thirty-one (57%) of 54 children with hippocampal sclerosis had associated ipsilateral anterior temporal changes. Ipsilateral anterior temporal atrophy was associated with anterior temporal changes (P <.03). Children whose images showed anterior temporal changes were younger at onset of epilepsy (P <.01) and younger at antecedent cerebral insult (P <.03) than those with normal anterior temporal lobes. Most (84%) children whose images showed anterior temporal changes had experienced the onset of epilepsy or antecedent cerebral insult before the age of 2 years (P <.0009). Eighty-one percent of children with anterior temporal changes shown on their images experienced seizures at the time of antecedent insult. CONCLUSION: Ipsilateral anterior temporal changes identical to those observed in adult cases are seen on the MR images of young children with hippocampal sclerosis, with a similar prevalence, and are associated with either epilepsy onset or seizure-related cerebral insult before the age of 2 years. We suggest that the loss of gray-white matter definition may represent a persistent immature appearance, including an abnormality of myelin or myelination, possibly a result of seizures occurring during maturation of the temporal pole.

Childhood chronic inflammatory demyelinating polyneuropathy with central nervous system demyelination resembling multiple sclerosis.

Central nervous system demyelination has been described in adults but not in children with chronic inflammatory demyelinating polyneuropathy. We describe a patient with clinical and electrophysiological features consistent with chronic inflammatory demyelinating polyneuropathy who presented at age 5 with an intramedullary spinal cord tumor-like lesion and at age 8, represented with cerebral and spinal demyelinating lesions. Her clinical course and magnetic resonance imaging features were atypical for multiphasic disseminated encephalomyelitis and indistinguishable from multiple sclerosis. To our knowledge, this association has not been previously described in the English literature in childhood.

Neonatal alloimmune thrombocytopenia: antenatal and postnatal imaging findings in the pediatric brain.

BACKGROUND AND PURPOSE: Neonatal alloimmune thrombocytopenia (NAIT) is a maternal-fetal platelet antigen incompatibility disorder estimated to occur in one of 2000 to 5000 neonates. The diagnosis is made serologically by showing parental platelet antigen incompatibility and the presence of maternal platelet antibodies. In the absence of formalized antenatal screening, the radiologist has an important role to play in the recognition of this disorder, which has significant implications for the index case and any subsequent offspring. Our aim was to characterize the neuroradiologic findings and identify, if possible, a consistent pattern of neurologic injury typical of NAIT. METHODS: We retrospectively reviewed the ultrasonograms, CT scans, MR images, and medical histories of six patients (21 weeks gestation to 9 years old) with intracranial injury secondary to serologically proved NAIT. RESULTS: Hemispheric porencephalic cysts (n = 6), primarily located within a temporal lobe with extension into other lobes, were seen on the ultrasonograms, CT scans, and MR images of all six children. In five cases, this was thought to represent encephaloclastic porencephaly and, in one case, schizencephaly (agenetic porencephaly). Six children had ventriculomegaly of varying degrees and severity and asymmetry. Extra-axial hemorrhages (n = 2), intraventricular hemorrhage (n = 1), acute parenchymal hemorrhage (n = 2), and neuronal migrational disorder (n = 1) occurred with varying frequency. CONCLUSION: Antenatal or early postnatal neuroradiologic imaging showing hemispheric porencephaly and lateral ventriculomegaly is a recognizable pattern of cerebral injury suggestive of the diagnosis of NAIT. In the absence of a cost-effective screening program of primiparous women and neonates for this disease, the radiologist has an important role to play in the recognition of this disease entity. It is crucial for the reporting radiologist to consider the possibility of NAIT in any child with antenatal hemorrhage and, more importantly, with the pattern of cerebral injury described above. Because a high percentage of subsequent pregnancies might be equally or more severely affected, antenatal management directed at preventing intracranial hemorrhages in utero has become of significant clinical importance.

Hemiconvulsion-hemiplegia-epilepsy syndrome: characteristic early magnetic resonance imaging findings.

We report three patients with hemiconvulsion-hemiplegia-epilepsy syndrome who presented acutely and were shown to have striking neuroimaging findings suggestive of diffuse cytotoxic edema confined to one hemisphere, including extensive diffusion-weighted imaging abnormalities in two cases. Two patients subsequently developed progressive and extensive atrophy of the involved hemisphere. These findings are consistent with earlier descriptions of the classic neuroradiologic features of this syndrome and are helpful in the differential diagnosis of acute infantile hemiplegia. Further, the findings support the previously proposed pathogenetic mechanism of neuronal injury caused by status epilepticus.