Biometry of the Cerebellar Vermis and Brain Stem in Children: MR Imaging Reference Data from Measurements in 718 Children.

BACKGROUND AND PURPOSE: Objective and quantitative data to define cerebellar vermis and/or brain stem hypoplasia in children are lacking. Our aim was to provide MR imaging biometric references for the cerebellar vermis and brain stem from a large cohort of children with normal cerebellums. MATERIALS AND METHODS: The MR imaging data were retrospectively selected from our hospital data base from January 1, 2014, to December 31, 2017. All MR imaging examinations of children between 1 day and 15 years of age, including midline sagittal sections, were included. Children with a clinical history or MR imaging abnormalities that may affect the posterior fossa were excluded. We manually measured four 2D parameters: vermian height, anterior-posterior diameter of the vermis, anterior-posterior diameter of the midbrain-pons junction, and anterior-posterior midpons diameter. The inter- and intraobserver agreement was evaluated. RESULTS: Seven hundred eighteen children were included (372 boys and 346 girls), from 1 day to 15 years of age. Normal values (third to 97th percentiles) were provided for each parameter. The vermis parameters showed a rapid growth phase during the first year, a slower growth until the fifth year, and finally a near-plateau phase. The brain stem parameters showed more progressive growth. The intra- and interobserver agreement was excellent for all parameters. CONCLUSIONS: We provide reference biometric data of the vermis and the brain stem using simple and reproducible measurements that are easy to use in daily practice. The relevance of these 2D measurements should be further validated in diseases associated with cerebellar abnormalities.

TSH-secreting adenoma improved with cabergoline.

TSH-secreting adenomas are rare tumors, representing only 0.5 to 2.5% of pituitary adenomas. Their main clinical characteristics include signs of thyrotoxicosis, diffuse goiter and a compressive syndrome. Biologically, free T4 and T3 serum levels are elevated, contrasting with inadequate serum TSH levels and increased alpha chains. Magnetic resonance (MR) imaging shows a pituitary tumor, the main differential diagnosis being resistance to thyroid hormones. Treatment is based on surgery, possibly associated with somatostatin analogs and radiotherapy. Though the long-term evolution of this rare pathology seems to have improved, some clinical situations are still a challenge to treat. We report one such case that was resistant to both stereotactic radiotherapy and somatostatin analogs, but surprisingly improved with cabergoline. We suggest that cabergoline should be considered as an alternative treatment in cases of pituitary adenomas that resist traditional treatments.

[New techniques of structural and functional MRI]. / Nouvelles techniques d'IRM morphologique et fonctionnelle.

Magnetic resonance imaging is an imaging technique allowing morphological and functional study of the brain. Algorithmic and technical advances offer new insights in such brain studies using new approaches to search epileptogenic lesion. Voxel based analysis appears as the dominant methodology to study grey and white matter using the following contrast: T1, T2, T2 relaxometry, magnetization transfert and diffusion weighted imaging. Ongoing development focuses on sulcal morphometry and gyrification index, to improve our understanding of developmental epilepsy. Magnetic resonance spectroscopy appears as a promising tool following availability of high field strength clinical MRI and evidence about its utility in the field of epileptology. Functional MRI benefits from such high field strength and new pulse sequence using diffusion gradients to probe neuronal firing.

[Structural MRI in adult partial epilepsy]. / IRM morphologique des épilepsies partielles de l'adulte.

Magnetic resonance imaging (MRI) is the prominent imaging modality in the field of epilepsy. MRI plays a major role in describing and recognizing the malformations of cortical development and hippocampal sclerosis and has improved epilepsy patient care. MRI is also accurate in detecting the other major epilepsy etiologies (vascular malformations and cicatricial lesions). Presurgical MRI is relevant since it provides a high-resolution study of the brain.

[Superficial hemosiderosis of the central nervous system improved by corticosteroids]. / Hémosidérose marginale du névraxe d'évolution favorable sous corticoïdes.

INTRODUCTION: Superficial siderosis is of the Central Nervous System (CNS) is an uncommon and often disabling disorder. There is no evidence that any treatment, including removal of an identified source of bleeding, affects disease progression. OBSERVATION: We report the case of a 49-year-old woman exhibiting progressive and various neurological disorders associating chorea, pyramidal syndrome, cerebellar ataxia, cognitive disorders and cranial nerve deficits. She had a prior history of right occipital arterioveinous malformation (AVM) revealed four years before by ventricular hemorrhage. The AVM was treated by radiosurgery. Because of a pronounced progression of the symptoms, treatment with steroid therapy was initiated before the diagnosis of siderosis of the central nervous system was asserted by magnetic resonance imaging (rim of hypo-intensity due to hemosiderin around the brainstem, the cerebellum and the spinal cord on T-2 weighted and gradient echo T-2* imaging) and cerebrospinal fluid (CSF) examination (high CSF levels of iron and ferritin). Over the next months the neurological condition improved under steroid therapy. CONCLUSION: Our observation is interesting because of the chorea movement disorders which are rarely reported in the disease and because of the improvement of the neurological condition after steroid therapy which is described in only another case in the literature. Steroid therapy could constitute a new track for the treatment of siderosis of CNS.

[Trichloroethylene intoxication presenting with temporal seizures]. / Crises temporales symptomatiques d'une intoxication au trichloroéthylène.

INTRODUCTION: Trichloroethylene (TCE) is extensively used as a degreasing agent in the metal industry and as a solvent for organic compounds. Its neurotoxicity (with respect to both the peripheral and central nervous systems) is now widely acknowledged. OBSERVATION: Here, we report the case of a 32-year-old male drug addict presenting temporal seizures after "huffing" TCE (i.e. voluntary inhalation). The patient also deve loped a "psycho-organic syndrome" which included cognitive dysfunction (with memory disorders in particular) and personality changes. These disorders had not been noticed by the patient's wife prior to the last episode of inhalation. Four months later, the cognitive disorders had stabilized and no further seizures had been observed. CONCLUSION: The patient's overall clinical picture (notably featuring neuropsychological disorders) and electroencephalographic and brain imaging data argue in favor of a selective effect of TCE on the temporal lobe.

[Main temporal aspects of the MRI signal of subdural hematomas and practical contribution to dating head injury]. / Principaux aspects évolutifs du signal des hématomes sous-duraux en IRM et intérêts pratiques dans la datation des traumatismes crâniens.

BACKGROUND AND PURPOSE: MRI signal of a subdural hematoma (SDH) is often regarded as similar to that of an intracerebral hematoma but no precise study has analyzed the evolution of the signal of subdural hematomas. Their dating is however significant, in particular in the child, within the context of the diagnosis of child abuse. The objective of this study is to compare with MRI a group of adult patients having a subdural and/or intracerebral, in order to study the evolution of the signals of these two types of hematomas. MATERIAL AND METHODS: This prospective study included patients hospitalized for post-traumatic acute subdural or intracerebral hematoma. The protocol included an emergency brain CT and 4 MRI at fixed times: in emergency (early phase), between the third and the seventh day (early subacute phase), during the third week (late subacute phase), and after four months after the hemorrhage. The protocol included T1-weighted sequences before and after injection of gadolinium, T2-weighted, fluid-attenuated inversion-recovery (FLAIR), gradient echo and diffusion. RESULTS: Eighteen patients were included and all 72 MRI were interpretable. The time course of the cerebral hematomas was similar to that described in the literature, whereas that of subdural hematomas was different in 15 patients. This distinction was significant in the early phase for subdural hematomas, which displayed hypersignal in T2 and FLAIR, whereas cerebral hematomas showed a hyposignal in the same sequences. The variation was also notable in the early subacute period during which subdural hematomas displayed hypersignal in T1, FLAIR and diffusion, and isosignal in T2, whereas cerebral hematomas showed isosignal in T1, and hyposignal in T2, FLAIR and diffusion. CONCLUSION: The time course of MRI signal of subdural hematomas is different from that of cerebral hematomas. This difference is significant in T2 sequence and FLAIR, especially in the early subacute period. These radiographic observations in adults can be useful for the MRI dating of subdural hematomas in shaken-baby syndrome.

[MR imaging in mental retardation]. / Imagerie par résonance magnétique du retard mental non spécifique.

Mental retardation is considered idiopathic or not otherwise specified when no etiological diagnosis can be identified in spite of comprehensive history, physical examination and metabolic or genetic investigations. In such cases, brain MRI is indicated for patients with abnormal head size or shape, craniofacial malformation, somatic anomalies, neurocutaneous findings, seizures, focal neurological findings or behavioral and/or developmental problems. Brain anomalies are now considered a main category for the etiology of mental retardation. MRI evaluation should include axial images of the entire brain, sagittal images through the midline structures, and coronal images of the posterior fossa or entire brain. MRI allows detection of major and or minor cerebral anomalies or malformations, sometimes multiple. In the literature, the most frequently involved structures include: 1/ corpus callosum (hypoplasia, short corpus callosum and verticalized splenium), 2/ septum pellucidum (cavum septum pellucidum or cavum vergae), 3/ ventricles (ventriculomegaly), 4/ cerebral cortex (cortical dysplasia), 5/ cerebellum (hypoplasia), and 6/ extra-axial CSF spaces (enlargement). In our patient population, dysplasia involving the cerebellum and vermis have been identified, a finding that has not yet been described in the literature. MRI allows detection of multiple minor morphological anomalies. Most have classically been considered as normal variants but they may in fact be markers of cerebral dysgenesis and are currently the only anomaly detected in the work-up of patients with mental retardation. Their role in the pathogenesis of mental retardation is under evaluation.

[MRI of hippocampal malformations in patients with intractable temporal lobe epilepsy]. / IRM des malformations de l'hippocampe dans l'épilepsie temporale réfractaire.

OBJECTIVE: In some patients with temporal lobe epilepsy, recent MRI studies have revealed several morphological features indicative of discrete hippocampal malformation (HM). Its prevalence is unknown and the relationship between the HM and the origin of seizures has never been investigated. Our purpose is to define the MRI findings of this new entity and to determine its incidence in a group of patients and in a control group in order to evaluate its clinical significance. MATERIALS AND METHODS: MR imaging findings in 97 patients suffering from medically intraceable temporal epilepsy were prospectively evaluated during the preoperative evaluation of surgical candidates. The MR-imaging protocol included oblique coronal slices perpendicular to the temporal lobes using high resolution T2 weighted (HR TSE T2), Fluid attenuated inversion recovery (FLAIR) and inversion-images. This protocol has been completed by axial FLAIR images and axial and sagittal IR images of the whole brain. Coronal HR TSE T2 images were performed in 50 healthy control subjects. Cerebral lesion and hippocampal morphology were evaluated in both groups. RESULTS: Fourteen patients (14%) showed hippocampal morphological modification. The most frequent and specific findings were lack of visualization of the internal hippocampal (lack of linear T2 hypointensity within the hippocampus) and the abnormal shape (pyramidal, vertically oriented or globular-shaped). Other signs were: abnormal position of the hippocampus (medically located hippocampus) and vertical collateral sulcus. Cases without visualization of the internal structure of the hippocampus were considered as a complete form of HM and were correlated with temporal epilepsy. A vertical collateral sulcus was observed in some control group subjects. CONCLUSION: Complete forms of HM could be considered as epileptogenic lesions. Nevertheless, interpretation of the incomplete form is delicate: the abnormal angle of the collateral sulcus can be encountered in healthy subjects and could therefore be considered a normal variant.

Apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR) in pediatric hypoxic-ischemic brain injury.

BACKGROUND AND PURPOSE: a review of the literature reveals the increasing interest in using Diffusion magnetic resonance imaging, with diffusion weighted images (DWI) and ADC (Apparent Diffusion Coefficient) quantitation, in pediatric hypoxic-ischemic brain injury. However, ADC and MTR (Magnetization Transfer Ratio) as quantitative tools have not been investigated together in these pathological conditions in young pediatric patients. The aim of this study was to apply a quantitative method by using ADC and MTR calculation in order to propose a reproducible quantitation of brain parenchymal lesions. METHODS: we conducted a prospective study including all children presenting with suspected cerebral hypoxic-ischemic injury. 15 children were included, among them 10 males and 5 females aged from 36 weeks of gestation to 17 months with a median age of 10,5 months. All MR examinations were performed at 1.5 Tesla unit including conventional MR (T1, T2 and Inversion-recovery sequences) and DWI with ADC map. ADC and MTR ROI (region of interest) measurements were made, in the frontal subcortical and periventricular white matter (WM) as well as in the gray matter (GM=basal ganglia), and in focal lesions. RESULTS: ADC and MTR values were abnormal in focal lesions and in diffuse injury with no evidence of lesion on conventional MRI and DWI. We observed a strong inverse correlation between these ADC and MTR (R=0,66 in WM; R=0,61 in GM). CONCLUSION: ADC and MTR calculation may be helpful as a reproductive method to quantify the lesions and detect diffuse lesions in hypoxic-ischemic pediatric brain injury.

[Management of patients after a first seizure]. / Conduite á tenir devant une première crise convulsive.

Neuroimaging evaluation in patients after a first seizure could be easily determined on the basis of seizure history, neurological examination, blood sample analysis and electroencephalography. The main objectives of the initial work-up are to differentiate a true seizure event from seizure-like symptoms, to exclude a single seizure as a manifestation of non organic cause and finally to consider the seizure as a result of cerebral lesion or inaugurate epilepsy. When a new onset seizure is diagnosed, urgent neuroimaging is recommended only in patients with focal neurological deficit, persistent or worsening alteration in the level of consciousness and when clinical and biological data lead to a suspected vascular or infectious etiology. Brain CT scan is usually more available in emergency to identify the cause of seizure. It may have an important role for the therapeutic strategy and may defer MRI investigation. Nevertheless, brain MRI must be performed in emergency when CT scan is not conclusive despite a severe clinical condition or in case of cerebral venous thrombosis. Imaging modalities depend on clinical data, patient age and suspected epilepsy type.

[Cerebellar cortical dysplasia: MRI aspects and significance]. / Dysplasie du cortex cérébelleux: aspects en IRM et signification.

Because it is now possible to obtain high-resolution multiplanar MR imaging of the cerebellum and because of the developing interest on the role of the cerebellum on higher brain functions, we have decided to study the process of cerebellar fissuration. All brain MRI examinations performed in children for varied neurological and neurosurgical indications, especially children with non-specific mental retardation and patients with cerebral malformation detected at initial imaging work-up, were reviewed. Fissuration and lobulation anomalies (abnormal orientation of fissures, pseudopolymicrogyria, cortical thickening, subcortical cysts and heterotopia) were identified that we called cerebellar cortical dysplasia (CCD). In order to better understand the origin of this malformation, current data on cerebellar embryogenesis and histogenesis will be reviewed, and the pathological and radiological features will be illustrated. Milder forms of CCD represent a distinct group of anomalies that should be distinguished from other types of cerebellar dysplasia (agenesis, hypoplasia or complex dysplasia with involvement of the cerebellar vermis (rhombencephalosynapsis)) or combined cerebellar and cerebral dysplasia (muscular dystrophies and lissencephaly). Recognition of cerebellar cortical dysplasia could be a first step towards a broader understanding of its pathogenesis and significance.

Supratentorial functional disturbances in two children with cerebellar cortical dysplasia.

When evaluating children with mental retardation, subtle cerebral and cerebellar morphologic anomalies are often noted at Magnetic Resonance Imaging (MRI). Some, such as cerebellar cortical dysplasia (CCD), have been considered as subtle markers of cerebral dysgenesis. Their functional significance and their effect on brain function, remain unknown. To study supratentorial functional disturbances related to CCD we performed Positron-Emission-Tomography (PET) studies in two children with isolated CCD, in order to investigate the degree of involvement of supratentorial structures. One had developmental delay, motor disturbances and ataxia, and the other one only had mental retardation. PET studies revealed hypoperfusion and hypometabolism within the vermis, thalamus and the right striatum in one case, and hypometabolism in the basal ganglia and cerebellar deep grey nuclei in the other case. Our results could lead to a hypothesis explaining motor disturbances as well as cognitive impairment, and could suggest a pathological functional significance of CCD. Nevertheless, the relationship between these findings and mental retardation needs further investigation.

[Neurenteric cyst: an unusual congenital malformation of the spinal canal]. / Le kyste neuroentérique: une malformation congénitale rare du rachis.

Neurenteric cyst is a rare congenital anomaly, which is included in the split notochord syndrome. The cyst arises from abnormal persistence of the neurenteric canal at about three weeks of gestation. The most common locations are extramedullary intradural. They can extend anywhere along the neuraxis. The intermittent, polymorphic and misleading clinical symptoms may result in a delay in diagnosis. Magnetic resonance imaging is the gold standard in the diagnosis of this anomaly. Surgical treatment allows total recovery in most cases.

Large-cell medulloblastoma with arrestin-like protein expression.

We report a case of a cerebellar large-cell medulloblastoma in a 12-year-old patient. Despite a gross-total resection followed by a radiation therapy and then a chemotherapy, the death occurred 6 months later. The cyogenetic analysis showed an isochromosome 17q. Immunoreactivity for synaptophysin, neurofilaments, chromogranin and arrestin-like proteins was detected, whereas rhodopsin, vimentin, EMA and PAX-6 were negative. In this study, we demonstrate that large-cell medulloblastoma with translocation in chromosome 17q is a neuronal differentiated medulloblastoma with non-photoreceptor characterization. By reverse transcription and polymerase chain reaction (RT-PCR) method, using primers for beta1, beta2 and visual arrestin, we demonstrate corresponding mRNA for beta1, beta2 arrestin but not for visual arrestin. These results suggest that arrestin immunoreactivity in this tumor corresponds to non-visual arrestin. This case corresponds to a new entity of large-cell medulloblastoma. The potential role of a new marker linked to a beta2 adrenergic receptor needs further molecular characterization to be useful.