Derek C. Harwood-Nash

Neuroimaging of childhood craniopharyngioma.

The imaging of craniopharyngioma may include plain skull x-rays, computer tomography (CT) scans, magnetic resonance imaging (MRI) and angiography. Coronal studies are essential to properly define the regional anatomy. The solid or cystic character of the lesion is especially apparent with contrast enhancement. MRI adds a sagittal projection which is useful, and its increasing sophistication may eventually make angiography superfluous in these tumours. The appearance of craniopharyngiomas in each modality is described, including 3D, and an ideal imaging strategy presented. Postoperative imaging is best done with both MRI and CT, and enhanced studies done within 48 h to avoid the effect of surgical trauma.

Magnetic Resonance Imaging Evaluation of Delayed Myelination in Down Syndrome: A Case Report and Review of the Literature

Magnetic resonance imaging has been found to be useful in assessing brain myelination and provides information on brain maturation. The normal pattern of brain myelination conforms to a fixed sequence, with good pathologic and MRI correlation. Neuropathologic analysis of myelination has shown delayed central myelination in Down syndrome. Delayed myelination on MRI in Down syndrome has not previously been reported. We report a case of Down syndrome with a significant delay in myelination as demonstrated on MRI. This 18-month-old infant had brain myelination equivalent to that expected for an 11-month-old infant. To determine the relative incidence, extent of delayed myelination, and time for recovery to full myelination in Down syndrome, more cases require examination and assessment. Magnetic resonance imaging has the advantage of serial assessment of myelination during brain maturation. (J Child Neurol 1992;7:417-421).

Congenital craniocerebral abnormalities and computed tomography.

U NTIL NOW, neuroradiologic techniques have demonstrated either ventricular and cisternal alterations or direct or indirect effects on the intracranial vessels. Computed tomography (CT) has added another dimension. It defines a specific tissue pattern of the brain itself, so that solid or fluid-filled lesions within and surrounding the brain can be identified. Although CT is a relatively noninvasive and certainly safe examination, especially in infants, the nuances of the often complex congenital anomalies it uncovers often require additional neuroradiologic procedures. It is not that CT fails to provide satisfactory images, but that such images are often more difficult to understand and interpret than those provided by angiography or pneumography. Intracranial anomalies of the brain are deviations in form and structure induced during the brain’s intrauterine development. It is the interaction between the genetic and the intrauterine environmental factors that ultimately produce the malformation. Ebaugh and Holt6 state that chromosome deviations account for lo%, inheritance (either recessive or dominant) for 20%, and intrauterine environmental factors such as infection for 10% of intracerebral malformations. No pathogenetic factor is present in the remaining 60%. Many segments of the immature central nervous system may be so completely altered in utero that a logical cause cannot be deduced. Cerebral dysgenesis may occur in the formative period of neural tube development (3 weeks or before) or during its later intrauterine maturation and development. A malformation may result from nonlethal neural tissue destruction, cessation of growth, or altered development of a large or small portion of the brain. Inflammatory reactions within the fetal brain are uncommon before the sixth month of fetal life. Yakovlev14 subdivided alterations of form and

Posterior fossa hemorrhages in the newborn.

Abstract: Of 700 neonates examined by computed tomography (CT) in a 4 year period, 17 were found to have a posterior fossa hemorrhage. Eleven were born at term, and six were premature. Delivery was traumatic in 12 babies. The hematoma was in the subdural space in nine and within the cerebellum in eight. The CT diagnosis of extravasated blood in the posterior fossa is easy both in full-term neonates and prematures. The localization of the hematoma, however, may be difficult. While in the full-term neonates differentiation between subdural and intracerebellar location is relatively easy, in the premature the cerebellar hematoma frequently has a crescentic shape that resembles a subdural collection. Four patients with a subdural hematoma and four with a cerebellar hematoma were operated on. The general prognosis is poor: seven patients died; of the survivors, only three are normal at follow-up.

Clinical significance of ventriculomegaly in children who suffered perinatal asphyxia with or without intracranial hemorrhage: an 18 month follow-up study.

One-hundred and thirty neonates who suffered perinatal asphyxia were divided into two groups according to maturity at birth. All the neonates were studied with computed tomography (CT) of the brain in the neonatal period and again at 6 months of age. They were all followed clinically until at least 18 months of age. Eleven infants (8%) developed progressive hydrocephalus needing surgical intervention, and 67 (51%) had ventriculomegaly that was not diagnosed as progressive hydrocephalus during the 18-month-long follow-up period. All 11 neonates who developed progressive hydrocephalus had had hemorrhage, but ventriculomegaly without progressive hydrocephalus was very common and as common among those who had had hemorrhage as among those in whom no hemorrhage was found in the neonatal CT scan. We conclude from this study that, although posthemorrhagic hydrocephalus is a not infrequent complication of intracranial hemorrhage in neonates, the diagnosis should be made with caution, since ventriculomegaly of etiologies other than progressive hydrocephalus is common in this group of patients. The CT scan should be evaluated together with the clinical course of the patient. This combined approach will minimize the risks of a false positive diagnosis of progressive hydrocephalus and subsequent overtreatment as well as lack of treatment in cases in which it is necessary.

Computed tomography of rhabdomyosarcomas of the skull base in children.

The computed tomographic (CT) findings of rhabdomyosarcomas involving the skull base in seven children are described. The tumor may arise in the nasopharynx, maxillary sinus, petrous bone, or orbit. Computed tomography clearly shows the full extent of bone destruction and replacement by soft tissue. The CT picture, however, is not specific and differential diagnosis with other aggressive lesions involving the base of the skull such as histiocytosis X, neuroblastoma, and lymphoma can be made only with a combined clinical and radiological approach.

Primary neoplasms of the central nervous system in children

Modern diagnostic imaging techniques are able to detect primary neoplasms of the central nervous system (CNS) in children safely and accurately but with less specificity as to cell type or degree of malignancy. These neoplasms, often peculiar in cell type and size, mediated by hydrocephalus in their clinical presentation, demand careful and often extensive imaging techniques best to evaluate their geography and character. Added to these basic observations, determination of the neoplasm from surrounding edema, detection of possible spread, and evaluation of residual or recurrent neoplasm are prime responsibilities of the pediatric neuroradiologist toward the child, neurosurgeon, and oncologist.

Cerebellar arteriovenous malformations in children.

Abstract We review the presentation, imaging findings and outcome in 18 children with cerebellar arteriovenous malformations (AVM). This group is of particular interest because of the reported poor outcome despite modern imaging and neurosurgical techniques. All children had CT and 15 underwent catheter angiography at presentation. Several of the children in the latter part of the study had MRI. Of the 18 children, 17 presented with a ruptured AVM producing intracranial haemorrhage. The remaining child presented with temporal lobe epilepsy and was shown to have temporal, vermian and cerebellar hemisphere AVM. This child had other stigmata of Osler-Weber-Rendu syndrome. Three other children had pre-existing abnormalities of possible relevance. One had a vascular malformation of the cheek and mandible, one a documented chromosomal abnormality and another a midline cleft upper lip and palate. Six of the 17 children with a ruptured cerebellar AVM died within 7 days of the ictus. Vascular pathology other than an AVM was found in 10 of the 14 children with a ruptured cerebellar AVM who had angiography: 4 intranidal aneurysms, 5 venous aneurysms and 2 cases of venous outflow obstruction (one child having both an aneurysm and obstruction). The severity of clinical presentation was directly related to the size of the acute haematoma, which was a reasonable predictor of outcome.

Computerized Tomography Appearance of Accidental Infusion of Air into the Venous Sinuses

A needle for intravenous fluid administration in a newborn was accidentally placed in the sagittal sinus and resulted in dural sinus air embolism. CT findings are described and the risks for venous air embolism are discussed.

Neuroimaging studies in children with temporal lobectomy

Twenty-eight children with intractable seizures who subsequently underwent a temporal lobectomy were studied by electroencephalogram (EEG), prolonged video EEG telemetry, computed tomography (CT), magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT) for the localization of epileptogenic foci. MRI showed abnormalities indicating epileptogenic foci in 21/25 patients and a increased signal intensity in 7/11 patients with mesial temporal sclerosis (MTS). SPECT showed corresponding abnormalities in 17/22 patients, including an interictal decrease in regional cerebral blood flow corresponding to the epileptogenic zone in 15. CT showed localized abnormalities in 16/28. All 12 patients with benign, slow-growing neoplasms showed an abnormality on CT scan. In children, MRI is essential in localizing epileptogenic abnormalities, especially MTS and cortical dysplasia. SPECT contributes to the localization of epileptogenic foci, which are often coincident with EEG abnormalities, particularly in single pathology. CT depicts benign neoplasms with calcification in the temporal lobe, which are likely to provoke complex partial seizures.