Postmeningitic ossification in pediatric cochlear implantation.

OBJECTIVE: The goals of this study were to retrospectively review high-resolution CTs (HRCTs) of pediatric postmeningitic cochlear implant recipients and to correlate results with surgical findings. METHODS: HRCTs of 20 children (11 months to 12 years old) who underwent implantation with multichannel devices were reviewed. Results were correlated with the degree of ossification observed at surgery. RESULTS: Ninety percent of subjects required drilling of ossified bone within the basal turn at surgery. HRCT of the cochleas suggested ossification within the basal turn in 45% (50% sensitivity). Ossification of the lateral semicircular canal on HRCT was present in 72% (77% sensitivity). Five of 6 cases without radiographic evidence of ossification had positive findings at surgery. CONCLUSION: Ossification is a common occurrence in postmeningitic deaf children. Ossification of the lateral semicircular canal on HRCT is a more sensitive measure for predicting ossification than evidence of cochlear involvement. Absence of ossification on HRCT is no guarantee of cochlear patency at the time of implantation.

Clinical impact of MR spectroscopy when MR imaging is indeterminate for pediatric brain tumors.

OBJECTIVE: We undertook this study to determine if single-voxel proton (hydrogen) MR spectroscopy could have clinical impact on the management of pediatric brain tumors when MR findings were indeterminate. SUBJECTS AND METHODS: Eleven children (mean age, 9 years) being examined for brain tumors underwent MR imaging that revealed indeterminate criteria of enhancement, mass effect, and prolonged T1 and T2 signal. MR spectroscopy was then used to distinguish radiation necrosis from tumor in one patient, differentiate residual tumor from scarring in two patients, document early treatment response in three patients, and discriminate benign from malignant masses in five patients. RESULTS: In 10 of the 11 patients, spectra were successfully acquired. Based on the chemical analysis of the indeterminate area shown on MR imaging, clinical impact was achieved in these 10 patients. Clinical impact included treatment modification in five patients, follow-up studies replacing further treatment in three patients, and tumor characterization in the remaining two patients. Confirmation was by histology in four patients and by follow-up MR imaging and MR spectroscopy for up to 30 months in the remaining six patients. CONCLUSION: When MR imaging is indeterminate in evaluating pediatric brain tumors, MR spectroscopy can provide objective neurochemical information, thereby altering treatment.

Transcranial Doppler imaging in pediatric abnormalities in older children.

Transcranial Doppler (TCD) is a noninvasive diagnostic ultrasound study which uses a 2 megahertz pulsed Doppler transducer to measure the velocity and pulsatility of blood flow within the major intracranial arteries. It has proved to be extremely useful as a screening test or to help confirm the diagnosis of several clinical conditions in infants and children. Some of the proved indications for TCD is for evaluating cerebrovascular occlusive disease especially in screening children with sickle cell disease, hydrocephalus, asphyxia and cerebral edema, confirming brain death, arteriovenous malformations, and vasoplasm. TCD technique, indications, and common pathological findings are emphasized.

MR imaging of symptomatic neurocutaneous melanosis in children.

Neurocutaneous melanosis is a syndrome consisting of cutaneous nevi and melanocytosis of the leptomeninges. Over a 5-year period (1989-1994) we evaluated with MR imaging the central nervous system of five children with a confirmed histologic diagnosis of neurocutaneous melanosis. The children ranged in age from 7 to 10 years and consisted of two girls and three boys. They all had multiple pigmented skin lesions (cutaneous nevi) and presented with seizures, signs of raised intracranial pressure, cranial nerve palsies and/or myelopathy. The MR studies were performed with T1-weighted, T2-weighted and T1-weighted post-gadolinium images of the brain in addition to T1-weighted post-gadolinium images of the entire spine. The MR findings in all the children consisted of marked, diffuse enhancement of thickened leptomeninges surrounding the brain and spinal cord which was only demonstrated on the post-gadolinium T1-weighted images and mild to moderate hydrocephalus. We present our MR findings and compare these findings with other imaging findings in the literature. Our findings represent part of a spectrum of imaging abnormalities seen in patients with neurocutaneous melanosis.

MR imaging of the pediatric spine.

An overview of MR imaging of the pediatric spine is presented with a systematic approach to the analysis of spinal dysraphic disorders. An introduction to the most commonly used MR imaging techniques, with an emphasis on the newer pulse sequence of cine MR flow of the cerebrospinal fluid and embryogenesis of the spine and spinal cord, provides the orientation for diagnosis of this common pediatric disorder.

Magnetic resonance spectroscopy (MRS) in the evaluation of pediatric brain tumors, Part II: Clinical analysis.

Over a 1-year period (1994-1995), 75 children with brain neoplasms were evaluated with a new automated magnetic resonance spectroscopy (MRS) software package called Proton Brain Exam/Single-Voxel (PROBE/SV) to determine the efficacy of this modality in children. The children ranged in age from newborn to 17 years and were comprised of 30 girls and 45 boys. The types of brain neoplasms consisted of 45 astrocytomas, 4 medulloblastomas, 2 ependymomas, 3 craniopharyngiomas, 3 germinomas, 1 pineoblastoma, 2 teratomas, 1 choroid plexus papilloma, 4 meningiomas, 2 astroblastomas, 3 rhabdoids, and 5 metastases from primary brain neoplasms. All children underwent magnetic resonance imaging (MRI) at the same setting as the MRS examination. The MRS examination was performed with the stimulated echo acquisition mode (STEAM) pulse sequence in all children, and occasionally the point resolved spectroscopy (PRESS) sequence also was used. Qualitative spectra were obtained in all children, and at times quantification data also were obtained. We found that our spectra over the brain neoplasms were consistent with the MRS findings of brain neoplasms in the literature. There was markedly elevated choline with markedly decreased or absent N-acetylasparate and at times elevated lactate and lipid peaks. In children with meningiomas, there was also an elevated alanine peak. We found MRS to be extremely useful in 1) characterizing a brain mass as a neoplasm, 2) differentiating radiation necrosis and radiation-induced meningiomas from the recurrent primary tumor, 3) following treatment response of the primary neoplasm, 4) differentiating residual or recurrent primary neoplasm from postsurgical changes, and 5) identifying inactive neoplasms or neoplasms in remission.

Magnetic resonance spectroscopy (MRS) in the evaluation of pediatric brain tumors, Part I: Introduction to MRS.

Magnetic resonance spectroscopy (MRS) provides a means to assess functional (metabolic activity) of the brain. It is now possible to perform MRS in a clinical setting with the use of an inexpensive software package called Proton Brain Exam/Single Voxel (PROBE/SV) developed by General Electric Medical System for use on their 1.5-T MR scanner. We have used PROBE for over a year and have found it to be useful in the evaluation of brain abnormalities. Most of our experience with MRS has been in the evaluation of children with brain tumors. In this first article of a two-part series, a simplified introduction to single-voxel MRS is presented, including: 1) the differences in the normal MRS spectra of the brains of infants, children, and adults demonstrating the variation in peaks of the common metabolities (N-acetylasparate, creatine, and choline); 2) the two types of MRS pulse sequences, stimulated echo acquisition mode (STEAM), a T1-weighted sequence, and point resolved spectroscopy (PRESS), a T2-weighted sequence; and 3) some of the factors that influence the production of diagnostic and nondiagnostic spectra. Part Two will report findings on the efficacy of MRS in children with brain tumors. With a basic understanding of MRS, the abnormal spectra in the diagnosis of brain tumors can be appreciated.

Neurocysticercosis among children in Chicago.

Neurocysticercosis has been diagnosed increasingly in the United States as a consequence of increased immigration from and travel to areas of endemic cysticercosis. We report a retrospective series of 47 pediatric cases of neurocysticercosis in our large children's hospital in Chicago, which has a large immigrant population. Neurocysticercosis was diagnosed on the basis of any of the following three criteria: (1) surgical biopsy findings, (2) radiographic findings consistent with neurocysticercosis as well as diagnostic serum and/or cerebrospinal fluid titers, or (3) consistent radiographic findings and a compatible epidemiologic history (without diagnostic serological findings). Epidemiologic, clinical, laboratory, and radiographic data were analyzed. Neurocysticercosis is a relatively common cause of afebrile seizures in children who present to our emergency department in Chicago. Computed tomography and magnetic resonance imaging are both important modalities in evaluation of children with neurocysticercosis. Laboratory studies are neither sensitive for nor predictive of the diagnosis of neurocysticercosis. Therapy is well tolerated. The long-term prognosis for treated patients appears to be excellent.

Imaging of terminal myelocystoceles.

This article presents a retrospective analysis of the presentation, imaging studies, and associated findings in 20 children with surgically and histologically proven terminal myelocystoceles. All 20 children presented at birth with a black mass; 13 had cloacal extrophy. The patient population was comprised of 15 girls and 5 with ambiguous genitalia: Of the imaging studies, 8 had plain radiographs, 6 myelography-computed tomography, 11 ultrasound, and 14 magnetic resonance. The associated findings included Chiari I (eight patients), Chiari II (one patient), hydromyelia (three patients), hydrocephalus (three patients), and vertebral segmentation anomalies (six patients). Magnetic resonance imaging was the best imaging modality to diagnose and evaluate children with a myelocystocele. Magnetic resonance imaging demonstrated the classic findings: a terminal cyst of the central canal of the spinal cord that is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysphria onto the back as a mass.

Craniofacial gliomas.

Ten patients with gliomas were treated between 1977 and 1993. Three of the lesions (30 percent) exhibited intracranial extension. Fifty percent (2 of 4) of the intranasal lesions exhibited intracranial extension. Effective removal of the lesion required manipulation of nasal bones in intranasal lesions and extranasal lesions with intranasal extension. Gliomas with an intracranial component were best addressed through a combined intracranial and extracranial approach.

MR of terminal myelocystoceles.

PURPOSE: To delineate the clinical and MR findings in children with an unusual type of spinal dysraphism, the terminal myelocystocele. Infants with a terminal myelocystocele carry a favorable neurologic prognosis if the entity is diagnosed early. Understanding the MR characteristics of this entity will allow for earlier and more accurate diagnosis. METHOD: Analysis of the medical charts and MR studies in 15 children with surgically and histologically proven myelocystocele. RESULTS: In all 15 children, MR demonstrated the primary findings of a terminal cyst of the central canal of the spinal cord which is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysraphia onto the back as a mass. Of these children, 10 had additional findings (one or more) on MR of Chiari I (five cases), Chiari II (one case), cervicothoracic hydromyelia (two cases), lumbar hydromyelia (two cases), hydrocephalus (2 cases) segmentation anomalies of vertebrae (3 cases) and partial agenesis of sacrum (six cases). Of the clinical findings, all 15 children had a back mass, 10 also had cloacal exstrophy. One had imperforate anus, 10 were girls, five had ambiguous genitalia and all were neurologically intact. CONCLUSION: Children with a terminal myelocystocele present with a back mass and there is a high association with cloacal exstrophy. MR is the best noninvasive modality to diagnose all of the components of a terminal myelocystocele and the associated central nervous system findings.

MR of leptomeningeal melanosis in children.

PURPOSE: To delineate the magnetic resonance (MR) appearance of leptomeningeal melanosis in children. METHOD: Retrospective review of the medical, surgical, pathologic and MR findings in four children with a confirmed histologic diagnosis of leptomeningeal melanosis. The brain MR was performed with T1- and T2-weighted images in all four children and three had T1-weighted post-gadolinium images. Two of the children also had T1-weighted post gadolinium spine images. RESULTS: The MR brain findings consisted of cortical plaque and nodular hyperintense lesions on the noncontrast T1-weighted images in one child, marked, diffuse leptomeningeal enhancement in two children, and an enlarged, hypointense left temporal lobe with adjacent mild leptomeningeal enhancement in one child. The MR spine findings consisted of diffuse leptomeningeal enhancement in one child and hyperintensity of the cerebrospinal fluid in the other. CONCLUSION: The T1-weighted pre- and post-contrast images were the best to demonstrate the MR findings in leptomeningeal melanosis which consisted of either diffuse or localized enhancement of the leptomeninges; or cortical plaque and nodular hyperintense lesions pre-contrast.

MR and CT imaging patterns in post-varicella encephalitis.

The aim of the investigation was to determine the patterns of cerebral involvement on computed tomography (CT) and magnetic resonance (MR) imaging in post-varicella encephalitis. Four children between the ages of 2 and 11 years presented over a 5-year period with a diagnosis of post-varicella encephalitis. Their imaging studies and clinical data were reviewed retrospectively. The medical histories of all four children were noncontributory except for recent bouts of chickenpox 1 week to 3 months prior to hospitalization. Three children presented with parkinsonian manifestations. Bilateral, symmetric hypodense, nonenhancing basal ganglia lesions were found on CT. These areas showed nonenhancing low signal intensity on T1-weighted images and high signal intensity on T2-weighted images on MR. One child presented with diffuse, multiple gray and white matter lesions of similar imaging characteristics; some lesions, however, did enhance. This child had no gait disturbances. Post-varicella encephalitis can produce two patterns of dramatic CT and MR findings. With an appropriate history and clinical findings, varicella as a cause of bilateral basal ganglia or diffuse cerebral lesions can be differentiated from other possible etiologies which include trauma, anoxia, metabolic disorders and demyelinating diseases.

Three-dimensional computed tomography imaging in the evaluation of craniofacial abnormalities.

A retrospective study was undertaken to assess the value of three-dimensional computed tomography (3-D CT) in evaluating craniofacial abnormalities. Over a 2-year period, 145 children evaluated with routine two-dimensional (2-D) CT had 3-D CT reformatted images assessing a variety of anomalies including craniosynostosis, midface clefts, trauma, and craniofacial syndromes. There were 62 females and 83 males ranging in age from 1 month to 17 years (median: 5 months). Both soft-tissue and bone algorithms were used. In all 145 cases, the 3-D CT images confirmed or provided additional information of depth perception, contours, volumes, and extent of an abnormality. This was especially important and useful in the settings of complex anomalies and preoperative planning. We concluded that 3-D CT reconstructed images in conjunction with routine 2-D CT should be an integral part of the examination in evaluating craniofacial abnormalities.

MR of pediatric intracranial meningiomas.

PURPOSE: To assess MR and pathologic characteristics of childhood intracranial meningiomas, comparing the radiographic findings with those observed in adult intracranial meningiomas. METHODS: Clinical records, MR and CT scans, and histology of eight children with intracranial meningiomas presenting for a period of 7.5 years were retrospectively reviewed. RESULTS: Boys equaled girls but predominated from ages 4 to 11 years. The ages ranged from 4 to 18 years. Two patients had radiation-induced meningiomas. Two children had multiple lesions; neither had neurofibromatosis. All solitary lesions were supratentorial. Other characteristics included: dural-based attachment (n = 6); large size (> 5 cm) (n = 4); cystic components (n = 3); and intraventricular location (n = 1). Histologic subtypes were: meningothelial (n = 4); transitional (n = 3); and fibroblastic (n = 1). Preoperative diagnoses of meningiomas were made in six cases based on overall imaging characteristics. CONCLUSIONS: Diagnosis of childhood intracranial meningiomas does not differ from that of adults radiographically, with the exception of larger tumor sizes.

Contrast agents in neuroimaging.

Until there is total elimination of adverse reactions and side effects with contrast agents, there will continue to be a need for improvement. The ideal contrast agent should be efficacious, safe, water soluble, with chemical and heat stability, biologically inert, with low viscosity, with osmolality the same as human serum, with selective excretion by the kidneys, and inexpensive.

Sickle cell trait and stroke in children.

Cerebrovascular complications of sickle cell anemia are well known to be one of the more common causes of stroke in the pediatric age group. Although it is far less common, the association of stroke with sickle cell trait has been described in young adults and only twice in children in the English literature. In this report, we describe a case of a posterior circulation infarct occurring in a 12-year-old male who also had a normal variant vertebral artery, which may have been a contributing factor in his presentation. The literature is reviewed and other possible risk factors for stroke in sickle cell trait are discussed.

The clinical and radiological evaluation of primary brain neoplasms in children, Part II: Radiological evaluation.

Data collected over the past 8 years on the radiological appearance of common pediatric primary brain neoplasms are presented. An emphasis is placed on the newer radiological imaging modality of magnetic resonance imaging (MRI). Part I of this article emphasized the clinical evaluation of these brain neoplasms. Three hundred eighty-five children with known brain neoplasms ranging in age from newborn to 18 years were evaluated with one or all of the following radiological modalities: MRI, computed tomography (CT), water-soluble myelography (WSM), WSM with CT, and angiography. Contrast-enhanced MRI and CT scans both were accurate in delineating these brain neoplasms although MRI provided better resolution and delineation than CT. Angiography provided information on the vascularity of the neoplasms and their relationship to prominent arterial and venous structures. Water-soluble myelography with CT and gadolinium-enhanced MRI of the spine were equally accurate in demonstrating metastatic spread to the spinal canal and spinal cord. Magnetic resonance imaging with gadolinium was more accurate than CT with contrast in demonstrating recurrent or residual neoplasm at the operative site and metastatic spread to the brain. Magnetic resonance imaging with gadolinium is the best radiological modality to fully evaluate pediatric brain neoplasms.

The clinical and radiological evaluation of primary brain tumors in children, Part I: Clinical evaluation.

In Part I of this article, we present our data collected over the past 8 years on the clinical evaluations of pediatric brain tumors with an emphasis placed on the more common neoplasms. Our data consists of 385 children ranging in age from newborn to 18 years. The majority of children presented with signs of raised intracranial pressure (including nausea, vomiting, and headaches), seizures or other focal neurologic deficits. Five percent of our children presented to outlying hospitals with symptoms that retrospectively turned out to be due to brain neoplasms but were misdiagnosed as "gastroenteritis," "viral upper respiratory tract infection," or even viral meningitis. These delays in diagnosis can cause serious negative outcomes for these patients and can be avoided through more careful neurologic and ophthalmologic examination at the time of first presentation. Central nervous system neoplasms are not uncommon in children and any child presenting with nausea, vomiting, and headaches should raise the suspicion of a primary brain tumor and should receive both a thorough neurologic exam and screening for papilledema. If papilledema is present, these children should be referred for proper neuroradiologic evaluation (which will be addressed in Part II.

Magnetic resonance imaging of the central nervous system in children with a new nonionic gadolinium contrast agent--gadoteridol injection (ProHance).

This article reports the results of clinical testing in pediatric patients of a new contrast agent, gadoteridol injection (ProHance), developed by Squibb Diagnostic as a nonionic gadolinium agent for use in magnetic resonance imaging (MRI). Thirteen children (four girls and nine boys) ranging in age from 10 to 18 years were enrolled in the study. The children had MR studies of the brain and/or spine with T1-weighted, T2-weighted, and postgadoteridol injection T1-weighted sequences. Five children had primary brain or spine neoplasms, three children had metastatic disease to the central nervous system, one child had a recurrent brain neoplasm and spinal canal metastasis, one child had an arteriovenous malformation, and two children were normal on the MRI studies. No minor or major reactions to gadoteridol injection developed in the 13 patients. Gadoteridol injection provided excellent delineation and enhancement of the arteriovenous malformation and all of the primary and secondary neoplasms of the central nervous system except for one case of a grade 1 glioma of the midbrain. Gadoteridol injection is a safe and excellent contrast agent for use in MRI.