Eric N. Faerber

Acute Disseminated Encephalomyelitis in Children: Discordant Neurologic and Neuroimaging Abnormalities and Response to Plasmapheresis

Objectives. To describe our experience with acute disseminated encephalomyelitis (ADEM), focusing on (1) the relationship between clinical course and MRI findings and (2) the response to plasmapheresis in a subgroup of patients. Methods. A retrospective record review was conducted of 13 children who were admitted as inpatients with the diagnosis of ADEM during the period 1998–2003. Results. Diagnosis was established by clinical signs and symptoms, cerebrospinal fluid changes and multifocal involvement of deep gray and white matter based on MRI. Initial therapy was high-dose methylprednisolone and intravenous immunoglobulin in 12 patients. One child improved spontaneously. Six of 12 children did not improve with corticosteroid treatment. All 6 had an acute progressive course neurologically, and 5 of them also showed a delay in the onset of neuroimaging changes, eventually developing lesions in the deep gray matter and brainstem. This latter group received 5 sessions of plasmapheresis and recovered over the course of several months with varying degrees of residual neurologic deficits. Conclusions. Presentation of ADEM with delayed development of MRI lesions in deep gray matter and brainstem may herald a prolonged clinical course and lack of response to glucocorticoid therapy. Plasmapheresis might be an effective therapeutic intervention in these patients. The role of plasmapheresis versus corticosteroids and intravenous immunoglobulin as a primary treatment of ADEM needs to be investigated further.

Abnormal diffusion-weighted MRI in medulloblastoma: does it reflect small cell histology?

Abstract A 12-year-old boy presented with the classic CT and MRI findings of medulloblastoma and the unusual finding of increased signal on diffusion MRI. The small-cell histology of medulloblastoma may account for the increased signal seen on diffusion MRI. Diffusion MRI with echoplanar technique may be useful in evaluation of these tumors and metastatic disease.

Desmoplastic cerebral astrocytoma of infancy. Light microscopy, immunocytochemistry, and ultrastructure.

The first detailed ultrastructural study of a superficial desmoplastic cerebral astrocytoma of infancy is reported. This is a neoplasm which mimics a mesenchymal tumor, originally described in 1984 under the name of “superficial cerebral astrocytoma attached to dura.” This tumor, which is believed to have a good prognosis, was resected from the frontoparietal region of a 6.5‐month‐old girl, in whom it had presented as a large densely enhancing vascular and cystic mass. The ultrastructure of the tumor appeared to be distinctive, characterized by the absence of neuronal elements, and the presence of large amounts of redundant and sometimes extensively duplicated basal laminal material and collagen between nonpleomorphic and nonlipidized astrocytes, corresponding to the reticulin fibers seen by light microscopic analysis between the S‐100 protein and glial fibrillary acidic protein (GFAP)‐positive cells. The features of the tumor, its differential diagnosis, and its relationship to other pediatric supratentorial tumors are discussed.

MRI appearances of metachromatic leukodystrophy

Background. The leukodystrophies constitute a wide spectrum of cerebral disorders of varying etiology. The imaging appearances on CT and MRI are recognizable as abnormalities of white matter; however, it may be impossible to arrive at the correct diagnosis based on imaging studies alone. Patients and methods. Three patients of varying age and clinical symptomatology diagnosed with metachromatic leukodystrophy (MLD) had remarkably similar MRI appearances. A “tigroid” or “leopard-skin” appearance was demonstrated within deep white matter in each case. Results. All of the patients had biochemical confirmation of MLD. Conclusion. Although the “tigroid” pattern previously was considered to be pathognomonic of Pelizaeus-Merzbacher disease, the diagnosis of MLD must now be considered when these MRI appearances are encountered.

A newly recognized cause of wheezing: AIDS‐related bronchial leiomyomas

We present two human immunodeficiency virus‐infected children who developed wheezing and radiological evidence of pulmonary air trapping due to intra‐ and peribronchial leiomyomas. At autopsy, leiomyomas were also found in their spleens, which to our knowledge, has never been reported. The smooth muscle tumors were strongly positive for the Epstein‐Barr virus, as demonstrated by in situ hybridization to Epstein‐Barr virus‐encoded ribonucleic acid, confirming the findings of recent investigators and linking these tumors to the Epstein‐Barr virus. Pediatr. Pulmonol. 1997;24:106–110.

Imaging Tumors of the Pediatric Central Nervous System

Primary tumors of the central nervous system (CNS) are the second most common neoplasms in children and the leading cause of death in this patient population. The primary objective of this article is to describe the most common pediatric brain tumors and to offer an overview of their respective imaging features, primarily on magnetic resonance imaging. Precise anatomic characterization is essential for developing an appropriate differential diagnosis. Once equipped with this critical information, physicians should be better able to make firm diagnoses, leading to improved disease management and patient outcomes in the setting of CNS tumors of childhood.

An Adolescent With a Mediastinal Mass, Diagnosed With Graves Disease and Thymic Hyperplasia

Graves disease is an autoimmune disorder characterized by thyroid enlargement and hyperthyroidism. Thyrotropin receptor (TSHR) autoantibodies bind the TSHR on the membrane of thyroid follicular cells and stimulate cell proliferation and thyroid-hormone synthesis. TSHR has also been identified in extrathyroidal organs, including the human thymus. Thus far, radiologically detectable thymic enlargement has only been reported in adults with Graves disease. We present here the case of a child with Graves disease and significant thymic hyperplasia. L. K. was a 15-year-old girl evaluated for cough and dyspnea on exertion. A chest radiograph was obtained, and it revealed a widened superior mediastinum. A computed-tomography scan of her chest identified a mass in the anterior mediastinum without associated lymphadenopathy. Because of these radiologic findings and her weight loss, she was referred to the oncology service; a biopsy of the mediastinal mass was obtained and revealed thymic reactive hyperplasia. Because of persistent tachycardia, thyroid studies were obtained, and the diagnosis of Graves disease was established. The childs physical examination revealed a minimally enlarged thyroid gland and no exophthalmos. One month after medical treatment was initiated, a repeat computed-tomography scan of her chest identified significantly reduced thymic size. To our knowledge, this is the first pediatric patient reported with Graves disease and significant thymic enlargement. Considering the diagnosis of Graves disease for a child with an anterior mediastinal mass and without the typical physical findings of autoimmune hyperthyroidism (goiter, exophthalmos) may prevent unnecessary diagnostic studies and their associated financial and emotional costs.

Magnetic resonance of metabolic and degenerative diseases in children.

Cerebral magnetic resonance imaging and spectroscopy form an integral part in the diagnosis and management of the vast spectrum of metabolic and degenerative disorders in children. These varied disorders have been classified in many different ways, according to anatomic location, head size, enzyme disorder, or cellular morphology and function. The clinical features and magnetic resonance imaging appearances of the most common disorders are discussed.

Infantile leukoencephalopathy owing to mitochondrial enzyme dysfunction.

Mitochondrial disease is classically associated with deep gray-matter lesions. When white matter is involved, the lesions are typically subcortical and overshadowed by more significant disease in the gray matter. We report six infants in five families who developed neurodegenerative diseases characterized primarily by abnormalities in deep white-matter structures such as the periventricular region, internal capsule, and corpus callosum. Five patients had impairments of mitochondrial enzymes, including a pre-electron transport chain defect and defects in respiratory chain complexes I, III, and IV (cytochrome-c oxidase). One patient, the sibling of one of the others, was diagnosed clinically with complex III deficiency. These six patients, along with others in the literature, appear to represent a distinct syndrome of mitochondrial infantile leukoencephalopathy. Our observations suggest that infants with leukoencephalopathies, especially leukodystrophies, who do not have one of the more common causes of white-matter disease should be evaluated for mitochondrial dysfunction. (J Child Neurol 2002;17:421-428).

Cerebral Syrinx with Chiari I Malformation

A 13-year-old female presented with acute left gaze paralysis. MRI revealed hydrosyringomyelia (HSM) with syringobulbia in the left pons extending cephalad into the centrum semiovale. A suboccipital craniotomy was performed and the foramen of Magendie was imperforate. Ocular movements normalized in 2 months and postoperative MRI confirmed resolution of the cerebral syrinx and syringobulbia and diminished HSM. This case represents an extreme example of the altered spinal fluid dynamics with Chiari I malformation. Theories on HSM are reviewed.