An atypical stapedial artery.

The persistence of the stapedial artery is a rare vascular anomaly. It is mostly asymptomatic but sometimes cause conductive hearing loss, pulsatile tinnitus, or vertigo. The estimated prevalence of this rare postembryonic persistence ranged from 0.02% to 0.48%. Four different anatomical forms have been identified, and their preoperative diagnostic is essential. We report the case of an incidental discovery of pharyngo-hyo-stapedial artery, the most uncommon form of persistent stapedial artery. Its per-operative finding has become rare because tomodensitometry is performed in case of conductive hearing loss. The continuous improvement of imagery resolution will probably help to revise the incidence of this malformation.

Hippocampal Sparing During Craniospinal Irradiation: What Did We Learn About the Incidence of Perihippocampus Metastases?

PURPOSE: To identify the incidence of patients with perihippocampal metastases to assess the risk of brain relapse when sparing the hippocampal area. Medulloblastoma (MB) represents 20% of pediatric brain tumors. For high-risk MB patients, the 3- to 5-year event-free survival rate has recently improved from 50% to >76%. Many survivors, however, experience neurocognitive side effects. Several retrospective studies of patients receiving whole brain irradiation (WBI) have suggested a relationship between the radiation dose to the hippocampus and neurocognitive decline. The hippocampal avoidance-WBI (HA-WBI) approach could partially reduce neurocognitive impairment in children treated for high-risk MB. METHODS AND MATERIALS: From 2008 to 2011, 51 patients with high-risk MB were treated according to the French trial primitive neuroectodermal tumor HR+5. Hippocampal contouring was manually generated on 3-dimensional magnetic resonance images according to the Radiation Therapy Oncology Group 0933 atlas. The distribution of metastases was assessed relative to the hippocampus: 0 to 5 mm for the first perihippocampal area and 5 to 15 mm for the rest of the perihippocampal area. RESULTS: The median patient age was 8.79 years (33% female). After a follow-up of 2.4 years, 43 patients were alive; 28 had had brain metastasis at diagnosis and 2 at relapse, with 16% in the first perihippocampal area and 43% in the rest of the perihippocampal area. Of the 18 patients without brain metastases at diagnosis, including M1 patients, none developed secondary lesions within the first or the rest of the perihippocampal area, after receiving 36 Gy. No clinical or biological factor was significantly associated with the development of perihippocampal metastases. CONCLUSIONS: Our results suggest the HA-WBI strategy should be evaluated for the subgroup of high-risk MB patients without metastatic disease.

New onset refractory convulsive status epilepticus associated with serum neuropil auto-antibodies in a school aged child.

We report a case of a child that suffered from a severe new onset status epilepticus a few days after a common viral infection. Despite extensive screening, no bacterial, viral or fungal infection could be found. Using immunohistochemical analysis, we found neuronal auto-antibodies directed against the neuropil, in blood and CSF, associated with CSF oligoclonal banding. Status epilepticus was highly refractory to antiepileptic drugs, but improved few days after Intra-Venous Immunoglobulin Injection (IVIG). The patient developed ongoing temporal lobe epilepsy that was still associated with neuropil auto-antibodies. Therefore, screening for antineuronal antibodies should be helpful to characterize and maybe to handle new onset status epilepticus without any obvious aetiology. Further studies should establish the link between epilepsy and such auto-antibodies.

Absence of IDH mutation identifies a novel radiologic and molecular subtype of WHO grade II gliomas with dismal prognosis.

The phenotypic heterogeneity of low-grade gliomas (LGGs) is still inconsistently explained by known molecular abnormalities in patients treated according to the present standards of care. IDH1 codon 132 and IDH2 codon 172 sequencing was performed in a series of 47 LGGs and correlated with clinical presentation, MR imaging characteristics, genomic profile and outcome. A total of 38 IDH1 mutations at codon 132 and 2 IDH2 mutations at codon 172 were found, including 35 R132H (87.5%), 2 R132C (5.0%), 1 R132S (2.5%) and 2 R172 M (5%). The IDH mutations were significantly associated with 1p19q deleted genotype (P = 0.031) and p53 expression (P = 0.014). The presence (vs. absence) of IDH mutations was associated with a better outcome (5-year survival rate, 93% vs. 51%, respectively, P = 0.000001). After adjustment for age, tumor location and size, radiologic infiltration pattern and extent of surgery, multivariate analysis confirmed that IDH mutations was an independent favorable prognostic factor (hazard ratio = 40.9; 95% CI, 2.89-578.49, P = 0.006). Furthermore, we showed that patients with IDH-nonmutated tumors were significantly older (P = 0.020) and that these tumors involved significantly more frequently the insula (P = 0.004), were larger in size (>6 cm, P = 0.047), displayed an infiltrative pattern on MRI (P = 0.007) and were all p53 negative with no 1p19q deletion (P < 10⁻6). The absence of IDH mutations in LGGs identifies a novel entity of LGGs with distinctive location, infiltrative behavior, specific molecular alterations, and dismal outcome. These findings could significantly modify the LGG classification and may represent a new tool to guide patient-tailored therapy.

Fetal magnetic resonance imaging of acquired and developmental brain anomalies.

During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.

Transient brain magnetic resonance imaging hyperintensity in basal ganglia and brain stem of epileptic infants treated with vigabatrin.

Vigabatrin is an antiepileptic drug that produces intramyelinic edema in several animal models. This study investigates the effect of vigabatrin on the developing human brain. The authors retrospectively blindly review 34 brain magnetic resonance imaging of 22 epileptic infants (age: 9 +/- 1 months) that received vigabatrin, focusing on the presence of hyperintensity on T2- and diffusion-weighted images. Patients treated with vigabatrin displayed significant magnetic resonance imaging hyperintensity of basal ganglia and brain stem (P < .001, Wilcoxon test). This hyperintensity was transient and maximal 3 to 6 months after the beginning of vigabatrin. Hyperintensity was independent from duration and type of epilepsy, and from the presence or absence of seizures. The authors conclude that vigabatrin treatment is associated with transient hypersignal of the basal ganglia and brain stem in epileptic infants. Such transient hyperintensity is likely to be age-dependent and time-dependent because it has never been observed in adult patients.

Evidence of lateralized anteromedial temporal structures involvement in musical emotion processing.

The right and left anteromedial temporal lobes have been shown to participate in emotion processing. The aim of the study was to further address their role in music emotion perception/recognition, and assessment by two emotional determinants, i.e., arousal (relaxing versus stimulating aspects) and valence (pleasantness degree). Epileptic patients with right or left anterior mesio-temporal resection (including the amygdala), and control subjects were presented with happy musical (chosen highly stimulating) or sad excerpts (chosen to be relaxing), that were either consonant (pleasant) or dissonant (unpleasant). The patients demonstrated an abnormal perception of dissonant music disregarding of the side of the resection; thereby confirming the role of the parahippocampal gyrus in the perception of unpleasantness. Moreover, the pleasantness of musical excerpts, in particular the happy consonant ones, was overestimated by patients with right temporal damage. In contrast, the arousal rating for happy consonant excerpts was reduced only in the group with left-resections. This modified perception of arousal might be related to the decreased ability of those patients to recognize happy and sad music. Indeed, both right and left temporal resections impaired sadness recognition, whereas happiness recognition was only reduced by the left-resections. The main result was that for the first time, the mesio-temporal structures were demonstrated to be asymmetrically involved in positive musical emotion recognition.

MRS of normal and impaired fetal brain development.

Cerebral maturation in the human fetal brain was investigated by in utero localized proton magnetic resonance spectroscopy (MRS). Spectra were acquired on a clinical MR system operating at 1.5 T. Body phased array coils (four coils) were used in combination with spinal coils (two coils). The size of the nominal volume of interest (VOI) was 4.5 cm(3) (20 mm x 15 mm x 15 mm). The MRS acquisitions were performed using a spin echo sequence at short and long echo times (TE = 30 ms and 135 ms) with a VOI located within the cerebral hemisphere at the level of the centrum semiovale. A significant reduction in myo-inositol and choline and an increase in N-acetylaspartate were observed with progressive age. The normal MR spectroscopy data reported here will help to determine whether brain metabolism is altered, especially when subtle anatomic changes are observed on conventional images. Some examples of impaired fetal brain development studied by MRS are illustrated.

Assessment of cortical maturation with prenatal MRI: part II: abnormalities of cortical maturation.

The fetal cortical maturation is a long process with predefined steps. Abnormalities can occur at different stages of cortical maturation, resulting in various malformations. They can result from disturbance in cell proliferation, cell differentiation, cell migration and in organization of the cortex. Analysis of the different abnormalities of cortical maturation is given with illustrations of the principal malformations encountered in utero and accessible to MRI.

Assessment of cortical maturation with prenatal MRI. Part I: Normal cortical maturation.

Cortical maturation, especially gyral formation, follows a temporospatial schedule and is a good marker of fetal maturation. Although ultrasonography is still the imaging method of choice to evaluate fetal anatomy, MRI has an increasingly important role in the detection of brain abnormalities, especially of cortical development. Knowledge of MRI techniques in utero with the advantages and disadvantages of some sequences is necessary, in order to try to optimize the different magnetic resonance sequences to be able to make an early diagnosis. The different steps of cortical maturation known from histology represent the background necessary for the understanding of maturation in order to be then able to evaluate brain maturation through neuroimaging. Illustrations of the normal cortical maturation are given for each step accessible to MRI for both the cerebral hemispheres and the posterior fossa.