MR imaging of neonatal spinal dysraphia: what to consider?

The development of the spinal canal and its contents is highly complex and involves multiple programmed anatomic and functional developmental and maturational processes. Correct and detailed knowledge about spinal malformations is essential to understand and recognize these lesions early (preferably prenatally) to counsel parents during pregnancy, to plan possible intrauterine treatments, and to make decisions about the mode of delivery and the immediate postnatal treatment. This article discusses the imaging findings of the most frequently encountered neonatal spinal malformations and correlates these findings with the relevant embryologic processes. The presented classification is based on a correlation of clinical, neuroradiologic, and embryologic data.

Bilateral germinoma of the basal ganglia.

Germinoma arising in the bilateral basal ganglia is exceedingly rare, with only five cases reported to date. Owing to non-specific clinical findings and the frequent presence of ill-defined abnormalities without a definite tumor mass on neuroimaging, the diagnosis can be difficult. We describe a case in which magnetic resonance spectroscopy (MRS) findings suggested a tumor and supported the decision to perform biopsy of the lesion.

Phenotypic characterization of hypomyelination and congenital cataract.

OBJECTIVE: To define the clinical and laboratory findings in a novel autosomal recessive white matter disorder called hypomyelination and congenital cataract, recently found to be caused by a deficiency of a membrane protein, hyccin, encoded by the DRCTNNB1A gene located on chromosome 7p21.3-p15.3. METHODS: We performed neurological examination, neurophysiological, neuroimaging, and neuropathological studies on sural nerve biopsy in 10 hypomyelination and congenital cataract patients from 5 unrelated families. RESULTS: The clinical picture was characterized by bilateral congenital cataract, developmental delay, and slowly progressive neurological impairment with spasticity, cerebellar ataxia, and mild-to-moderate mental retardation. Neurophysiological studies showed a slightly to markedly slowed motor nerve conduction velocity in 9 of 10 patients, and multimodal evoked potentials indicated increased central conduction times. Neuroimaging studies demonstrated a diffuse supratentorial hypomyelination, with in some patients, additional areas of more prominent signal change in the frontal region. Sural nerve biopsy showed a slight-to-severe reduction in myelinated fiber density, with several axons surrounded by a thin myelin sheath or devoid of myelin. INTERPRETATION: Hypomyelination and congenital cataract is a novel autosomal recessive white matter disorder characterized by the unique association of congenital cataract and hypomyelination of the central and peripheral nervous system.

Tumors of the spine in children.

In children, tumors of the spine are much rarer than intracranial tumors. They are classified into intramedullary, intradural-extramedullary, and extradural tumors. Magnetic resonance imaging provides crucial information regarding the extent, location, and internal structure of the mass, thus critically narrowing the differential diagnosis and guiding surgery.

Laryngeal schwannoma in an 8-year-old boy with inspiratory dyspnea.

BACKGROUND: Schwannomas of the larynx are rare lesions in the pediatric age group. METHODS: In this article, we report on the neuroimaging features of a schwannoma arising from the left aryepiglottic fold in an 8-year-old boy with a 6-month history of inspiratory dyspnea. RESULTS: Neuroimaging showed a well-defined, avoid mass originating from the left aryepiglottic fold. The lesion was removed endoscopically. CONCLUSION: Complete removal of laryngeal schwannomas is curative, and adjuvant treatment is not required.

Deficiency of hyccin, a newly identified membrane protein, causes hypomyelination and congenital cataract.

We describe a new autosomal recessive white matter disorder ('hypomyelination and congenital cataract') characterized by hypomyelination of the central and peripheral nervous system, progressive neurological impairment and congenital cataract. We identified mutations in five affected families, resulting in a deficiency of hyccin, a newly identified 521-amino acid membrane protein. Our study highlights the essential role of hyccin in central and peripheral myelination.

Neuroimaging of pediatric craniopharyngiomas: a pictorial essay.

Craniopharyngiomas are benign, partly cystic epithelial tumors that account for 5-13% of all intracranial tumors and 50% of all suprasellar masses in children. They pose several challenges to the neuroradiologist. This paper aims to focus on the main issues regarding the neuroradiological diagnosis and follow-up after treatment. Topics include (i) the imaging modalities (i.e., CT and MRI) utilized in the diagnostic workup; (ii) the neuroradiological appearance, focusing on calcifications, cystic components, contrast enhancement, and location; (iii) the relationships to adjacent structures, such as the optic chiasm, hypothalamus, third ventricle, and circle of Willis; (iv) the differential diagnosis with other tumoral and non-tumoral entities occurring in the sellar/suprasellar area; and (v) post-treatment imaging issues.

Spectrum of nonterminal myelocystoceles.

OBJECTIVE: To present the magnetic resonance imaging features, clinical findings, and possible embryologic bases for nonterminal myelocystoceles, a distinct subset of closed spinal dysraphisms. METHODS: We retrospectively analyzed imaging series and clinical records from five newborns and one older child with skin-covered soft tissue masses along the posterior midline spine. Spinal (6 patients) and brain (5 patients) magnetic resonance imaging was performed before surgical repair and compared with clinical findings, observations at surgery, and final lesion histology. RESULTS: The lesions affected the cervical (n = 3), thoracic (n = 2), and lumbar (n = 1) regions. In each case, the dome of the mass was covered by thickened, dystrophic epithelium with no subcutaneous fat, whereas the base and lateral walls of the mass were covered by normal skin. All patients were neurologically intact at presentation. In three cases, a stalk emanated from the dorsal normal spinal cord, crossed a narrow posterior bony spina bifida, and coursed through a posterior meningocele to attach to the inner aspect of its dome. The other three cases showed dissection of a hydromyelic cavity into the stalk, converting it into a second "cyst" within the meningocele. Concurrent anomalies included focal hydromyelia immediately cranial to the origin of the posterior stalk (n = 2), mild Chiari II malformation (n = 3), triventricular hydrocephalus from aqueductal stenosis (n = 1), filar lipoma (n = 1), and presumed neurenteric cyst (n = 1). At surgery, the sac was resected in all cases, but intradural exploration and untethering was performed in only three children. Embryologic considerations indicate that the spectrum of these lesions likely arises from partial limited closure of the neural tube, failed disjunction of the cutaneous ectoderm, and variable degrees of hydromyelia. CONCLUSION: The nonterminal myelocystocele is a distinct form of closed spinal dysraphism characterized by a skin-covered meningocele, which is either crossed by a fibroneurovascular stalk that extends from the dorsal aspect of the spinal cord to attach to the dome of the meningocele (abortive form, or myelocystocele manqué) or contains a hydromyelic cavity that is continuous with the ependymal canal of the spinal cord (complete form).

Prenatal MR imaging of dural sinus malformation: a case report.

OBJECTIVE: To describe prenatal magnetic resonance imaging (MRI) findings of dural sinus malformation (DSM), a very rare, congenital form of dural arteriovenous shunt (DAVS), typically affecting newborns. METHODS: Ultrasound (US) and MRI were performed at 34 weeks' gestation, and the findings of these examinations were compared with postnatal MRI studies performed at 2 days and 1 month. RESULTS: US showed an anechoic, midline posterior fossa collection with irregular internal echodensities. Color Doppler showed prominent arterial vascularity at the lesion margins. The prenatal MRI showed a large, profoundly hypointense, midline retrocerebellar mass. Postnatal MRI, complemented with magnetic resonance (MR) angiography, showed the lesion to be a giant dural venous pouch fed by multiple mural arteriovenous shunts. Follow-up MRI at 1 month suggested latent venous hypertension and prompted endovascular treatment. CONCLUSION: Prenatal MR imaging is useful to establish the diagnosis, to assess complications such as hydrocephalus and tonsillar prolapse, and to help plan perinatal management, postnatal follow-up, and treatment decision-making.

Hypothalamic-pituitary magnetic resonance imaging in growth hormone deficiency.

The accurate analysis of the hypothalamic-pituitary area is essential in the diagnosis of endocrine-related diseases. High-quality magnetic resonance imaging represents the examination modality of choice in the evaluation of hypothalamic-pituitary morphology. Indeed, the advent of molecular biology and neuroimaging techniques has led to significant progress in the understanding of the pathogenesis of disorders affecting the pituitary gland, specifically by demonstrating a clear phenotype-genotype relationship. Animal studies, along with the correlation of a particular genetic profile to certain endocrine and magnetic resonance imaging phenotypes in humans, have yielded great insights into pituitary development. Today, there is convincing evidence to support the hypothesis that marked magnetic resonance imaging differences in pituitary morphology indicate a variety of disorders that affect anterior pituitary gland organogenesis and function with a variety of diverse prognoses.

Epidural compression in neuroblastoma: Diagnostic and therapeutic aspects.

The involvement by tumour of intervertebral foramina and the consequent invasion of the spinal space, accompanied or not by neurological symptoms, represent a well-recognised pattern of presentation of neuroblastoma. The main peculiarity of this condition stands in the fact that, in case of its late detection or inadequate treatment, severe, permanent neurological compromise may ensue. Surprisingly enough, remarkable disagreements still exist regarding its optimal treatment and the related literature provide contrasting indications at this respect. The neurosurgical and the chemotherapeutic approaches have equally convinced supporters, while the use of radiation therapy is uncommon, possibly without good reasons. This mini-review intends to report the clinical experiences of the major Paediatric Oncology Groups with the aim to collect as many data as possible in the perspective of establishing common guidelines for proper diagnosing and treatment of this important complication.

Comparison of gadobenate dimeglumine (Gd-BOPTA) with gadopentetate dimeglumine (Gd-DTPA) for enhanced MR imaging of brain and spine tumours in children.

BACKGROUND: Gadobenate dimeglumine (Gd-BOPTA) demonstrates superior enhancement of brain tumours in adult patients than Gd-DTPA. OBJECTIVE: To determine whether Gd-BOPTA has advantages over Gd-DTPA for enhanced MR imaging of paediatric brain and spine tumours. MATERIALS AND METHODS: Sixty-three subjects, aged 6 months to 16 years, who were enrolled in a prospective, fully blinded, randomized parallel-group phase III clinical trial, received 0.1 mmol/kg doses of either Gd-BOPTA (n=29) or Gd-DTPA (n=34). The MR images were acquired before and within 10 min of contrast agent injection. The primary objective was to compare the difference from pre-dose to post-dose lesion visualization between Gd-BOPTA and Gd-DTPA. Lesion visualization was determined as the sum of individual scores for three criteria of lesion morphological characteristics (lesion border delineation, internal morphology, and contrast enhancement), each assessed qualitatively using 4-point scales. Quantitative evaluation compared changes in lesion-to-background (LBR) and contrast-to-noise (CNR) ratios and per cent enhancement. Monitoring for adverse events and evaluation of vital signs and laboratory values was performed. RESULTS: Pre-dose to post-dose changes in lesion visualization were significantly better for Gd-BOPTA for both lesion level (2.68+/-2.17 vs. 1.05+/-1.90, P=0.0106) and patient level (2.55+/-2.18 vs. 1.14+/-1.68, P=0.0079) comparisons. The mean pre-dose to post-dose change in CNR was greater for Gd-BOPTA (9.13+/-15.36) than Gd-DTPA (2.18+/-9.90), but the difference was only marginally significant (P=0.0779; 95% CI: -0.553, 14.454) because of wide variations of signal intensity between lesions. Similar findings were obtained for LBR and per cent enhancement. No differences between the agents were noted in terms of safety parameters. CONCLUSIONS: At an equivalent dose Gd-BOPTA is significantly better than Gd-DTPA for visualization of enhancing CNS tumours in paediatric patients.

Genetic disorders affecting white matter in the pediatric age.

Pediatric white matter disorders can be distinguished into well-defined leukoencephalopathies, and undefined leukoencephalopathies. The first category may be subdivided into: (a) hypomyelinating disorders; (b) dysmyelinating disorders; (c) leukodystrophies; (d) disorders related to cystic degeneration of myelin; and (e) disorders secondary to axonal damage. The second category, representing up to 50% of leukoencephalopathies in childhood, requires a multidisciplinar approach in order to define novel homogeneous subgroups of patients, possibly representing "new genetic disorders" (such as megalencephalic leukoencepahlopathy with subcortical cysts and vanishing white matter disease that have recently been identified). In the majority of cases, pediatric white matter disorders are inherited diseases. An integrated description of the clinical, neuroimaging and pathophysiological features is crucial for categorizing myelin disorders and better understanding their genetic basis. A review of the genetic disorders affecting white matter in the pediatric age, including some novel entities, is provided.

MR imaging of brain-stem hypoplasia in horizontal gaze palsy with progressive scoliosis.

We present the MR imaging findings of a girl with horizontal gaze palsy and progressive scoliosis (HGPPS). HGPPS is a rare congenital disorder characterized by absence of conjugate horizontal eye movements and accompanied by progressive scoliosis developing in childhood and adolescence. MR imaging depicted brain-stem hypoplasia with absence of the facial colliculi, presence of a deep midline pontine cleft (split pons sign), and a butterfly configuration of the medulla. These MR imaging features suggest the diagnosis of HGPPS and correlate with the clinical findings. We hypothesize that maldevelopment of dorsomedial brain-stem structures plays a crucial role in the pathogenesis of HGPPS.

Imaging in spine and spinal cord malformations.

Spinal and spinal cord malformations are collectively named spinal dysraphisms. They arise from defects occurring in the early embryological stages of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal dysraphisms are categorized into open spinal dysraphisms (OSDs), in which there is exposure of abnormal nervous tissues through a skin defect, and closed spinal dysraphisms (CSD), in which there is a continuous skin coverage to the underlying malformation. Open spinal dysraphisms basically include myelomeningocele and other rare abnormalities such as myelocele and hemimyelo(meningo)cele. Closed spinal dysraphisms are further categorized based on the association with low-back subcutaneous masses. Closed spinal dysraphisms with mass are represented by lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category further comprises defects of midline notochordal integration (basically represented by diastematomyelia) and defects of segmental notochordal formation (represented by caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging (MRI) is the preferred modality for imaging these complex abnormalities. The use of the aforementioned classification scheme is greatly helpful to make the diagnosis.

Leigh Syndrome with COX deficiency and SURF1 gene mutations: MR imaging findings.

Mutations in the nuclear SURF1 gene are specifically associated with cytochrome c oxidase (COX)-deficient Leigh syndrome. MR imaging abnormalities in three children with this condition involved the subthalamic nuclei, medulla, inferior cerebellar peduncles, and substantia nigra in all cases. The dentate nuclei and central tegmental tracts were involved in two cases each (all instances), and the putamina, interpeduncular nucleus, and pallido-cortical-nigro-cortical tracts in one. MR imaging pattern recognition can suggest an underlying COX deficiency and should prompt investigators to search for SURF1 gene mutations.

Early-onset cobalamin C/D deficiency: epilepsy and electroencephalographic features.

PURPOSE: To describe epilepsy and EEG findings in the early-onset cobalamin (Cbl) C/D deficiency, an inborn error of intracellular Cbl metabolism characterized by high plasma levels of methylmalonic acid, homocystine, and homocysteine. METHODS: Type and frequency of seizures were studied in 10 patients (six boys and four girls) who underwent waking and sleep EEG. RESULTS: Half of patients had seizures in the first year of life (either concurrent with the other symptoms of disease or some months after the onset of disease); seizures occurred after 2 years in the other half of patients. Convulsive status epilepticus was the initial manifestation in three patients. During the follow-up, nine patients had seizures (mainly partial) despite specific treatment for Cbl C/D deficiency and antiepileptic drugs. Focal or multifocal epileptiform abnormalities during waking EEG that increased during sleep EEG were recorded in the majority of patients. Plasma levels of homocystine and homocysteine were constantly higher than normal, despite therapy institution. CONCLUSIONS: Epilepsy and EEG abnormalities are prominent features in the early-onset type of combined methylmalonic aciduria and homocystinuria due to Cbl C/D deficiency, possibly related to the pathologically and persistently high levels of homocysteine, experimentally proven to induce seizures. Plasma amino acids evaluation and urinary acid organic analysis should be performed in any infant showing seizures associated with feeding difficulties and failure to thrive, at onset during the first year of life, as well as in any child with convulsive status epilepticus and a history of psychomotor developmental delay of unknown origin.