White matter abnormalities in children with idiopathic developmental delay

BACKGROUND

The underlying cause of developmental delay (DD) often remains unclear despite extensive clinical examination and investigations. Interference in normal development of the brain may result in DD.

PURPOSE

To identify the prevalence of abnormalities on magnetic resonance (MR) imaging in idiopathic developmental delay.

MATERIAL AND METHODS

Of the 124 children referred for MR imaging with DD, 34 were excluded due to known history of progressive neurodevelopmental disorders, birth asphyxia, congenital CNS infections, metabolic disorder, chromosomal anomalies, and severe epileptic syndromes. The following structures were systematically reviewed: ventricles, corpus callosum, gray and white matter, limbic system, basal ganglia, brainstem, and cerebellum.

RESULTS

Ten out of 90 (11%) were referred with DD only, whilst 80/90 (89%) were referred with DD and additional clinical findings, such as seizures, neurological deficit, and abnormal head size. Of the 90 patients, 14 (16%) had normal MR and 76 (84%) had abnormal MR findings. Abnormal ventricles were seen in 43/90 (48%); abnormal corpus callosum was identified in 40/90 (44%). Other MR findings included abnormalities in the white matter (23/90, 26%), hippocampi (5/90, 6%), cerebellum (5/90, 6%), and brainstem (4/90, 4%).

CONCLUSION

Abnormalities of the ventricles and corpus callosum were identified in a large proportion of patients with idiopathic DD, indicative of changes in the white matter. Further studies using quantitative methods and diffusion tensor imaging are required to evaluate the white matter in these children.

Rhombencephalosynapsis: prenatal imaging and autopsy findings

OBJECTIVES

Rhombencephalosynapsis is a rare, but increasingly recognized, brain malformation characterized by congenital fusion of the cerebellar hemispheres and absence of the vermis. Rhombencephalosynapsis is associated with significant developmental delay, seizures and involuntary head movements. We report four cases, with correlation of prenatal and postnatal imaging and autopsy findings.

METHODS

Over a 2-year period, four cases of rhombencephalosynapsis were diagnosed in the perinatal period, three in one center and one in another center. The clinical cases were reviewed, and correlation was made between the prenatal and postnatal imaging and autopsy findings where available.

RESULTS

All cases presented initially with ventriculomegaly on prenatal ultrasound examination. Subsequent magnetic resonance imaging (MRI) established the diagnosis in two cases and postnatal MRI established the diagnosis in a further two cases. Autopsy was available and confirmed the diagnosis in two cases. In one case the pregnancy was terminated, two infants died in the neonatal period and one died in infancy.

CONCLUSIONS

The cases in this perinatal series of rhombencephalosynapsis showed a very poor prognosis. The presence of ventriculomegaly on prenatal ultrasound imaging should alert the physician to consider rhombencephalosynapsis in the differential diagnosis. MRI appears to be the imaging modality of choice in establishing the diagnosis.

Radiographic features of tumefactive giant cavernous angiomas

BACKGROUND

Giant cavernous angiomas (GCAs) are very rare, and imaging features of GCAs can be very different from those of typical cavernous angiomas (CAs), making them a diagnostic challenge. The purpose of the study was to evaluate the radiographic features of GCAs, with an emphasis on the differentiating features from neoplastic lesions.

METHODS

The neuroradiological findings of 18 patients who harbored a histologically verified GCA (CA of 4 cm or larger) were reviewed retrospectively. The magnetic resonance imaging (MRI) appearance, enhancement pattern, presence of edema or mass effect, size, and location of each lesion were recorded. When available, pertinent clinical information, including age, sex, and mode of presentation, was obtained.

FINDINGS

Seizures, neurologic deficits, hemorrhage, and hydrocephalus were the most common presenting symptoms. The lesions were hyperdense and nonenhancing on computed tomography with frequent calcifications. On MRI, the lesions most commonly had a multicystic appearance, representing blood of various ages, and multiple complete hemosiderin rings. GCAs can present in any location with associating edema and mass effect, giving them a tumefactive appearance. No developmental venous anomaly was observed with any lesion.

CONCLUSIONS

Most GCAs in our series presented as multicystic lesions with complete hemosiderin rings on MRI, giving a "bubbles of blood" appearance. Although this characteristic feature is helpful in the diagnosis of many cases of GCAs, the correct diagnosis in the remaining cases may not be apparent until histopathological evaluation of the specimen is made.

Hypomyelination with atrophy of the basal ganglia and cerebellum: Follow-up and pathology

BACKGROUND AND OBJECTIVE

Hypomyelination with atrophy of the basal ganglia and cerebellum is a recently defined disorder. Only a few patients have been described. We report on 11 additional patients and new MRI findings and provide histopathologic confirmation of the MRI interpretation.

METHODS

We reviewed the patients' clinical history and present findings. We scored the MRI abnormalities. The histopathology of one patient was re-examined.

RESULTS

The patients' early psychomotor development was normal or delayed, followed by increasing extrapyramidal movement abnormalities, ataxia, and spasticity. Mental capacities were variably affected. MRI showed hypomyelination with, on follow-up, evidence of further myelin loss and variable white matter atrophy. The putamen was small or, more often, absent; the head of the caudate nucleus was decreased in size. In contrast, the thalamus and globus pallidus remained normal. Cerebellar atrophy was invariably present. Histopathology confirmed the myelin deficiency, probably related to both lack of deposition and low-grade further loss. The degeneration of putamen was subtotal. The cerebellar cortex was affected, particularly the granular layer.

CONCLUSION

Hypomyelination with atrophy of the basal ganglia and cerebellum is a syndrome diagnosed by distinctive MRI findings. Histopathology confirms hypomyelination, low-grade further myelin loss, subtotal degeneration of the putamen, and cerebellar cortical atrophy. All known patients are sporadic, and the mode of inheritance is unclear.

Midline "brain in brain": an unusual variant of holoprosencephaly with anterior prosomeric cortical dysplasia

INTRODUCTION

We report three cases of brain malformation presenting with a midline mass of dysplastic cortex that we have termed "brain in brain" malformation.

RESULTS

The three cases have holoprosencephalic features, including bilateral hemispheric continuity across the midline, single ventricle, midline facial defect and missing olfactory bulbs. All three cases have a midline conglomerate mass of deeply infolded, cortex-lined fissures with major arterial branches, heterotopia and large amount of white matter. The dysplastic mass of cortex and white matter extended into the third ventricle. The cortex and white matter of the dysplastic lesion was continuous with the cortex and white matter, respectively, of the cerebral hemispheres.

CONCLUSION

The midline "brain in brain" malformations have some similarities to subcortical heterotopia and extracerebral glioneuronal heterotopia. However, the continuity with the cerebral hemispheres and extension into the ventricle were not reported in subcortical or glioneuronal heterotopia. The common involvement of the midline cortex and extension into the third ventricle implied an anterior segmental prosencephalic abnormality (prosomeres 5/6). However, its pathogenesis remains to be explained.

Sudden infant death in a patient with FGFR3 P250R mutation

P250R mutation in the FGFR3 gene also known as Muenke syndrome is associated with coronal craniosynostosis, sensorineural deafness, craniofacial, and digital abnormalities. We report a family with this mutation associated with sudden death in an affected newborn, most probably due to upper airway obstruction.

Prenatal diagnosis of fetal exencephaly associated with amniotic band sequence at 17 weeks of gestation by fetal magnetic resonance imaging

We report a fetus with exencephaly diagnosed by fetal magnetic resonance imaging (MRI) at 17 weeks of gestation. Fetal ultrasound performed at 13 and 17 weeks of gestation suggested occipital encephalocele. However, the fetal MRI done at 17 weeks of gestation showed exencephaly and suggested amniotic bands as the cause. By providing early and precise information regarding the abnormality and the possible etiology, the fetal MRI enabled us to provide the couple and their families with accurate information regarding the low recurrence risk of this condition.

2D time-of-flight MR venography in neonates: anatomy and pitfalls

BACKGROUND AND PURPOSE

The dural venous sinuses in neonates differ from those in adults or older children in that the caliber of venous sinuses is smaller and there is skull molding. The aim of this retrospective study is to evaluate the presence of flow gaps in venous sinuses in neonates on 2D time-of-flight (TOF) MR venography (MRV).

METHODS

Fifty-one neonates underwent coronal 2D TOF MRV. Nine also had CT venography (CTV) for comparison. In 1 neonate, a further 2D TOF MRV was performed in the sagittal plane; in another neonate, images were captured in the axial plane; and in another, a further coronal TOF MRV with shorter echo time was performed.

RESULTS

Flow gap was seen in the posterior aspect of the superior sagittal sinus in 35 of 51 (69%). Focal narrowing of the superior sagittal sinus, in the region of convergence of lambdoid sutures, was detected in 7 of 51 (14%). The right and left transverse sinuses demonstrated flow gap in 13 of 51 (25%) and 32 of 51 (63%) respectively. There was normal filling of contrast on CTV in the superior sagittal sinus, transverse sinus and sigmoid sinus in those cases with flow gap detected on coronal 2D TOF MRV. Right, left, and codominance of the transverse sinuses are as follows: 32 of 51 (63%), 5 of 51 (10%), and 14 of 51 (27%), respectively. The right and left sigmoid sinuses demonstrated flow gap in 7 of 51 (14%) and 8 of 51 (16%), respectively, and the left sigmoid sinus was absent in 1 of 51 (2%).

CONCLUSION

The high proportion of flow gap in the venous sinuses of neonates, particularly of the superior sagittal sinus, could be attributed to the smaller caliber venous sinuses, slower venous flow, and skull molding.

Alexander disease: Ventricular garlands and abnormalities of the medulla and spinal cord

BACKGROUND

Alexander disease is most commonly associated with macrocephaly and, on MRI, a leukoencephalopathy with frontal preponderance. The disease is caused by mutation of the GFAP gene. Clinical and MRI phenotypic variation have been increasingly recognized.

METHODS

The authors studied seven patients with Alexander disease, diagnosed based on mutations in the GFAP gene, who presented unusual MRI findings. The authors reviewed clinical history, MRI abnormalities, and GFAP mutations.

RESULTS

All patients had juvenile disease onset with signs of brainstem or spinal cord dysfunction. None of the patients had a macrocephaly. The MRI abnormalities were dominated by medulla and spinal cord abnormalities, either signal abnormalities or atrophy. One patient had only minor cerebral white matter abnormalities. A peculiar finding was the presence of a kind of garland along the ventricular wall in four patients. Three patients had an unusual GFAP mutation, one of which was a duplication mutation of two amino acids, and one an insertion deletion.

CONCLUSION

Signal abnormalities or atrophy of the medulla or spinal cord on MRI are sufficient to warrant DNA analysis for Alexander disease. Ventricular garlands constitute a new sign of the disease. Unusual phenotypes of Alexander disease are found among patients with late onset and protracted disease course.

Atypical phenotype in a boy with a maple syrup urine disease

Maple syrup urine disease (MSUD) is a metabolic disorder due to a block in the decarboxylation step in the catabolic pathways of the branched-chain amino acids (BCAAs). We describe an atypical presentation in an infant male. The patient presented with psychomotor retardation, profound hypotonia and elevated plasma levels of BCAAs, but no elevation of alloisoleucine. Cranial magnetic resonance imaging showed prominent diffuse CSF spaces, delayed myelin maturation and symmetrical signal abnormality within the globi pallidi, midbrain, dorsal pons and medulla. The cerebellar white matter was specifically spared. A mitochondrial disorder was suggested. After correction of feeding problems with G-tube feeds, his high BCAAs persisted and, on fourth analysis, alloisoleucine was seen. Subsequent fibroblast enzyme and mutation analysis confirmed MSUD due to E(1)-alpha subunit deficiency. After starting dietary treatment, there was no significant improvement in his hypotonia or his psychomotor development. However, the high signal within the globi pallidi had resolved. MSUD may have diverse clinical presentations, and should be considered in children who present with chronic psychomotor delay but no acute encephalopathic episodes. BCAA levels may not be very high, alloisoleucine may not always be detected in MSUD even with severe enzyme deficiency, and imaging may be misleading if seen in the chronic phase only.

[61-year-old patient with long-term diarrhea and reactive depressive mood disorder]

Unser Fallbericht beschreibt nahezu exemplarisch das Krankheitsbild einer kollagenen Kolitis mit teils episodenhaft auftretenden, zuletzt persistierenden wässrigen Diarrhoen ohne Blut- oder Schleimbeimengungen. Die möglichen Auslöser waren eine dauerhafte NSAR- und Simvastatin-Medikation einerseits und eine abgelaufene Yersinien-Infektion andererseits. Eine chronische Diarrhoe, bei der eine infektiöse Genese und eine chronisch-entzündliche Darmerkrankung ausgeschlossen werden kann, sollte den behandelden Arzt immer auch an das Vorliegen einer mikroskopischen, insbesondere kollagenen Kolitis denken lassen. Die differentialdiagnostische Fehldiagnose «Reizdarm» oder «funktionelle Darmbeschwerden (Colon irritabile)» kann in solchen Fällen eine langjährige Morbidität, unter Umständen mit reaktiver Depression wie in diesem Fall, hervorrufen. Für den endoskopisch tätigen Gastroenterologen unterstreicht der hier vorgestellte Fallbericht die Notwendigkeit der Entnahme von Biopsien aus dem gesamten Kolonrahmen zur histologischen Aufarbeitung, auch bei makroskopisch blanden Schleimhautbefunden.

Prenatal ultrasound findings of lissencephaly associated with Miller-Dieker syndrome and comparison with pre- and postnatal magnetic resonance imaging

OBJECTIVE

To report on the prenatal ultrasound findings in fetuses with lissencephaly associated with Miller-Dieker syndrome (MDS) and to compare these findings with those of magnetic resonance imaging (MRI).

METHODS

Cases of MDS confirmed by postnatal chromosome microdeletion analysis were identified through review of patient records. Prenatal ultrasound scans were reviewed retrospectively by two radiologists. For cerebral cortical development, the Sylvian, parieto-occipital and calcarine fissures, and the cingulate sulcus and sulci over the cerebral convexity were evaluated. If one or more of these fissures or sulci were not visualized at the expected gestational age or their appearance was abnormal for gestational age, cortical development was considered delayed. Prenatal and postnatal MRI examinations were reviewed by a pediatric neuroradiologist.

RESULTS

There were seven cases of MDS. In three cases, the prenatal diagnosis of agyria/lissencephaly was prospectively suspected by ultrasound at 23, 26 and 30 weeks, and subsequently confirmed by prenatal MRI. When we retrospectively reviewed the prenatal ultrasound scans of all fetuses, all had delayed cortical development identified on ultrasound performed after 23 weeks' gestation. In all cases the Sylvian fissure was abnormal on both ultrasound and MRI. In one fetus, a normal cortical appearance for gestational age was seen at the initial 20-week ultrasound examination, but delayed cortical development was identified at a 24-week scan. Mild ventriculomegaly was seen in six fetuses and dysgenesis of the corpus callosum in one. Extracranial abnormalities were detected in five fetuses. Delayed cortical development was seen in two fetuses with mild ventriculomegaly, but no other fetal anomalies.

CONCLUSIONS

In fetuses with MDS, delayed cortical development can be suspected on ultrasound as early as 23 weeks' gestation. This finding warrants further investigations including MRI and FISH analysis for chromosome 17p13.3 deletion.

Cochlear implant positioning in children: a survey of patient satisfaction

INTRODUCTION

The past decade has been witness to significant diminution in incision size and placement for pediatric cochlear implantation at our institution. Furthermore, the orientation of the long axis of the implant relative to the skull base plane has generally evolved from a retro-verted to ante-verted direction to accommodate the ear level receiver stimulator and the new minimal access technique.

OBJECTIVE

To characterize the cosmetic, functional and clinical implications of this evolution in cochlear implant positioning by means of a patient satisfaction survey.

METHODS

A survey of patient satisfaction was administered to 100 cochlear implant recipients or their parents. The survey elicits the patient's level of satisfaction with respect to implant position and functional limitations. In addition, the angle formed by the long axis of the implant and the skull base plane (implant angle) was determined from lateral skull radiographs to detect the temporal evolution in implant positioning.

RESULTS

Analysis of the radiographs revealed an implant angle of 65.4-125 degrees in patients implanted prior to 1997, an implant angle of 56.3-87.5 degrees in patients implanted from 1997 to 2001, and an implant angle of 35.1-78.1 degrees after 2002. In spite of this evolution in positioning, the patient satisfaction survey did not reveal any change in incidence of cosmetic, functional or clinical problems.

DISCUSSION

The significant changes in incision and implant positioning represent a technical evolution in pediatric cochlear implant surgery. The fact that patients have been consistently satisfied over time suggests that the cosmetic, functional and clinical implications are minimal.

The locus responsible for horizontal gaze palsy/progressive scoliosis and brainstem hypoplasia is refined to a 9-cM region on chromosome 11q23

Horizontal gaze palsy associated with progressive scoliosis (HGPS) is a rare autosomal recessive condition that has been recently mapped to a 30-cM region on chromosome 11q23-25. In this report, we describe a consanguineous family in which three of five sibs are affected with HGPS. In two of the affected sibs, there was significant cognitive delay in addition to congenital horizontal gaze palsy and childhood onset scoliosis. In all three affected sibs, magnetic resonance imaging (MRI) scans revealed brainstem hypoplasia, a finding that has recently been associated with HGPS. Clinical examination of the family showed no significant dysmorphic features, while karyotyping, EMG, nerve conduction, and muscle biopsies were unrevealing. Homozygosity mapping was performed to narrow the disease locus on 11q23-25. A recombination event was observed in one affected sib between markers D11S1345 and D11S4464, which further refined the region to a 9-cM interval. Since the MRI results provide support for the theory that maldevelopment of neurons in the abducens nuclei and caudal longitudinal fascicle is the cause for HGPS, we speculate on the existence of a gene in this 9-cM interval on chromosome 11q23, which is critical for brainstem development.

Unilateral agenesis of the parotid gland: an unusual entity

Agenesis of the parotid gland is extremely rare with only few cases reported in the medical literature. This entity can be important to diagnose as occasionally the normal parotid gland can be mistaken for a tumor due to the facial asymmetry. In this article, we present the case of an isolated unilateral parotid gland agenesis in a young child. The entity is discussed along with important associated conditions that should be ruled out. These include amongst others first and second branchial arch anomalies, as well as the Levy-Hollister or lacrimo-auriculo-dentodigital syndrome.

Optic pathway glioma: correlation of imaging findings with the presence of neurofibromatosis

BACKGROUND AND PURPOSE

Despite the benign histology of optic pathway glioma (OPG) (low-grade astrocytoma), its biological behavior is unpredictable, and it is unclear whether specific morphologic or anatomic patterns may be predictive of prognosis. It is also unclear whether OPG associated with neurofibromatosis (NF) is a distinct entity from non-NF-OPG. Our purpose was to describe the MR imaging features of OPG, compare the findings between patients with and those without NF, and identify prognostic imaging signs.

METHODS

MR examinations of 91 patients with OPG (47 with NF and 44 without) were reviewed at presentation and during follow-up. The images were evaluated for size and extension of tumor, and imaging parameters. Statistical bivariate analysis was used to compare the patients with and those without NF, and Pearson correlation was used to evaluate the correlation between the different imaging parameters and prognosis. Kappa values were calculated to determine intraobserver and interobserver variability.

RESULTS

The most common site of involvement in the NF group was the orbital nerve (66%), followed by the chiasm (62%). In the non-NF group, the chiasm was the most common site of involvement (91%); the orbital nerves were involved in only 32%. Extension beyond the optic pathway at diagnosis was uncommon in the NF group (2%) but frequent in the non-NF group (68%). In the NF group, the tumor was smaller and the original shape of the optic pathways was preserved (91% vs. 27% in the non-NF group). The presence of cystic components was significantly more common in the non-NF patients (66% vs. 9% in the NF group). During follow-up, half the NF patients remained stable, in contrast to 5% of the non-NF group. No statistical correlation was found between imaging features and biological behavior of the tumor.

CONCLUSION

NF-OPG is a separate entity from non-NF-OPG, with different imaging features and prognosis, thereby warranting a specific diagnostic, clinical, and therapeutic approach.

Alexander disease: diagnosis with MR imaging

BACKGROUND AND PURPOSE

To date, the demonstration of Rosenthal fibers on brain biopsy or autopsy specimens is considered a prerequisite for a definitive diagnosis of Alexander disease. We initiated a multiinstitutional survey of MR abnormalities in both presumed and confirmed cases of Alexander disease to assess the possibility of an MR-based diagnosis.

METHODS

MR imaging studies in three patients with an autopsy-based diagnosis of Alexander disease were analyzed to define MR criteria for the diagnosis. These criteria were then applied to 217 children with leukoencephalopathy of unknown origin.

RESULTS

Five MR imaging criteria were defined: extensive cerebral white matter changes with frontal predominance, a periventricular rim with high signal on T1-weighted images and low signal on T2-weighted images, abnormalities of basal ganglia and thalami, brain stem abnormalities, and contrast enhancement of particular gray and white matter structures. Four of the five criteria had to be met for an MR imaging-based diagnosis. In a retrospective analysis of the MR studies of the 217 patients, 19 were found who fulfilled these criteria. No other essentially new MR abnormalities were found in these patients. In four of the 19 patients, subsequent histologic confirmation was obtained. The clinical symptomatology was the same in the patients with and without histologic confirmation and correlated well with the MR abnormalities. MR abnormalities were in close agreement with the known histopathologic findings of Alexander disease.

CONCLUSION

The defined criteria are sufficient for an in vivo MR imaging diagnosis of Alexander disease; only in atypical cases is a brain biopsy still necessary for a definitive diagnosis.

Characterization and expression analysis of two human septin genes, PNUTL1 and PNUTL2

The presence and role of septin proteins in yeast is well documented, but there is a growing appreciation for this family of proteins beyond yeast and extending to human cells. In this report we present the characterization and comparison of two highly similar human septin genes, PNUTL1 and PNUTL2. We compare the exon/intron structure of both genes, the steady-state mRNA levels in tumor cell lines and adult organs, the conceptual translation products from alternatively processed mRNAs and the development of specific immunologic reagents distinguishing either PNUTL1 or PNUTL2. The results illustrate a remarkable similarity between the two genes and their protein products while identifying specific differences in mRNA expression patterns. A summary of the described functional roles for mammalian septins is discussed along with an attempt to assimilate the alternative nomenclature existing for the same human septins, such as references to PNUTL1 and PNUTL2 as hCDCrel-1 and hCDCrel-2, respectively. The characterization of PNUTL1 and PNUTL2 represents a fundamental step in completing the characterization of the entire family of human septin genes.

Predictive value of computed tomographic myelography in obstetrical brachial plexus palsy

Preoperative radiologic studies to detect root avulsions of the brachial plexus caused by birth trauma are considered useful in assisting with surgical planning for reconstruction. In this study, the predictive value of computed tomographic (CT) myelography in detecting nerve root avulsions at our institution was determined. Sixty-three consecutive patients with an obstetrical brachial plexus palsy who had had both preoperative CT myelography and reconstructive surgery were selected. All CT myelograms were analyzed post hoc by a single neuroradiologist in a manner blind to the surgical findings. At each root level of the brachial plexus, the presence of a pseudomeningocele was noted along with the presence or absence of rootlets within each identified pseudomeningocele. Extraforaminal root avulsions later determined at surgery were reviewed by a single surgeon in a manner blind to the radiographic results. Surgical and radiographic findings were then compared at each corresponding root level. A total of 281 roots were examined. The sensitivity, specificity, positive predictive value, and likelihood ratio for root avulsions with pseudomeningoceles were 0.63, 0.85, 0.40, and 4.2, respectively. For pseudomeningoceles for which rootlets traversing the sac could not be identified, these values were 0.37, 0.98, 0.74, and 18.5, respectively. The presence of pseudomeningoceles with or without rootlets was not a sensitive indicator of root avulsions. Root avulsions were better predicted by identifying the absence of rootlets in a pseudomeningocele. This absence on CT myelography may be used to suggest an extraforaminal root avulsion due to its high specificity and high likelihood ratio.

Neurofibromatosis bright objects in children with neurofibromatosis type 1: a proliferative potential?

OBJECTIVES

The purpose of this study was to investigate the natural history of the high signal intensities shown on long TR sequences-neurofibromatosis type 1 bright objects (NBO)-in children with neurofibromatosis type 1 (NF1). We have paid particular attention to the development of tumors in these areas of abnormality.

METHODS

During a 12-month period in 1992 to 1993, 46 children with clinically proven NF1 had a magnetic resonance (MR) examination at our institution. These were reviewed along with any previous or subsequent MR examinations that had been performed. We recorded the number, volume, and distribution of the abnormal high signal intensities and their change with time when serial examinations were performed.

RESULTS

NBO were found in 93% of 46 children with NF1 on the original cross-sectional study. The most common anatomic sites were the globus pallidus (30.4%), cerebellum (23.5%), and midbrain (16.2%). The number and volume of NBO varied significantly with age. NBO were uncommon in children younger than 4 years but were very common and extensive between 4 to 10 years. A significant reduction in the number and volume of NBO was demonstrated in children older than 10 years as shown on both the cross-sectional and longitudinal portions of the study. Eight brain tumors (nonoptic pathway) were demonstrated in the 46 children (17%) with 1 child having two tumors. Only 1 child had symptoms referable to the tumor at the time of diagnosis. Five tumors developed in NBO that were documented on serial MR examinations. All those cases developed in children aged 7 to 12 years, and all these children had higher than average numbers and volumes of NBO.

CONCLUSIONS

NBO occur commonly in children with NF1 and are most prevalent between the ages of 4 and 10. We have shown a high frequency of brain tumors in our children with NF1, but the majority of these were asymptomatic. We have demonstrated proliferative change NBO in 11% of 46 children. Most NBO regress with age and seem to be benign, however, young children with a large number and volume of NBO should be followed closely with regular MR examinations because of an increased risk of proliferative change. neurofibromatosis type 1, magnetic resonance, tumor, astrocytoma, childhood.