François Chalard

Brain iron levels in attention-deficit/hyperactivity disorder: a pilot MRI study.

Abstract Objective. Brain iron deficiency has been supposed to be involved in the pathophysiology of ADHD. Available studies assessing iron in ADHD are based on serum ferritin, a peripheral marker of iron status. To what extent serum ferritin correlates with brain iron (BI) is unclear. The main aim of this study was to compare BI, estimated with magnetic resonance imaging (MRI) in the putamen, pallidum, caudate, and thalamus, between children with and without ADHD. The secondary aim was to assess the correlation between serum ferritin and BI levels. Methods. Thirty-six children (18 with and 18 without ADHD, the latter including nine healthy controls and nine psychiatric controls) completed MRI and blood sampling. Brain iron levels were estimated by imaging T2*. Results. Children with ADHD showed significantly lower estimated BI in right and left thalamus compared to healthy controls. Estimated BI did not differ significantly between children with ADHD and psychiatric controls. Children with ADHD had significantly lower levels of serum ferritin than healthy as well as psychiatric controls. Serum ferritin and T2* values did not correlate significantly in most regions. Conclusions. Low iron in the thalamus may contribute to ADHD pathophysiology.

Aortic dilatation in Turner syndrome: the role of MRI in early recognition

Background: Aortic dilatation and dissection are rare but important complications of Turner syndrome that increase the risk of sudden death in young patients. Objective: To assess the value of aortic MRI in patients with Turner syndrome; in particular to demonstrate early aortic dilatation. Materials and methods: A total of 21 patients with Turner syndrome underwent MRI of the thoracic aorta with measurement of vessel diameter at four levels. Results: Measurements were normal for age in 15 cases, two patients presented with values at the upper limit of normal and four had obvious dilatation of the ascending aorta. All were symptom free. Conclusions: MRI allows the non-invasive demonstration of early aortic dilatation, which may lead to earlier surgery in asymptomatic individuals.

Chiari type I malformation causing central apnoeas in a 4-month-old boy

Apnoea is a rare but well-known clinical presentation of the Chiari type I malformation. It may be either obstructive or central in nature, and has been described in children, adolescents and adults. Here, we report a 4-month-old infant who presented with frequent central sleep apnoeas leading to the diagnosis of a Chiari type I malformation. Surgical repair resulted in complete resolution of the symptoms, normal respiratory parameters during sleep and normal psychomotor development. This case illustrates a very early presentation of the Chiari type I malformation with central apnoeas and suggests that this aetiology should be considered in the differential diagnosis of central apnoeas in infants, especially when they are associated with other neurological sign or symptom.

Correlation between pre‐ and postnatal cerebral magnetic resonance imaging

To evaluate the diagnostic accuracy of fetal cerebral magnetic resonance imaging (MRI) on a large cohort and to compare pre‐ and postnatal MRI data.

A locus for sacral/anorectal malformations maps to 6q25.3 in a 0.3 Mb interval region

Partial absence of the sacrum is a rare congenital defect that also occurs as an autosomal-dominant trait, whereas imperforate/ectopic anus is a relatively common malformation, usually observed in multiple congenital anomalies syndromes. We report on a girl born to healthy consanguineous parents (first cousins once removed) with anal imperforation and associated rectovaginal fistula and partial sacral agenesis. Facial dysmorphism included a high forehead, epicanthic folds, downslanting palpebral fissures, hypertelorism and a depressed nasal root. Brain MRI showed a bilateral opercular dysplasia with a unilateral (right) pachygyria; MRI and X-ray imaging of the spine disclosed a tethered cord associated with partial sacral agenesis. She showed a moderate developmental delay. Ophthalmologic examination evidenced bilateral microphthalmos and relative microcornea. Cytogenetic studies in our patient disclosed a pure de novo 6q25.3 → qter deletion. By genotype analysis, we detected in our patient a maternal allele loss encompassing D6S363 and D6S446. Pure distal 6q deletion is a rare anomaly, reported in association with sacral/anorectal malformations (sacral agenesis, anal imperforation/ectopia) and never with cortical dysplasia. Pooling deletion mapping information in patients with pure terminal and interstitial 6q deletion allowed us to define a critical region spanning 0.3 Mb between the markers D6S959 and D6S437 for sacral/anal malformations. We hypothesize that haploinsufficiency for a gene within the deleted region may impair normal development of caudal structures, possibly acting on the notochordal development.

An atypical case of segmental spinal dysgenesis

Spinal segmental dysgenesis is a complex closed dysraphism. The diagnostic criteria are: lumbar or thoracolumbar vertebral dysgenesis causing kyphosis, focal spinal cord narrowing without exiting roots, deformity of the lower limbs and paraplegia or paraparesis. We present a newborn who showed atypical features of bifocal spinal cord narrowing, without any vertebral abnormality at the proximal level. This seems to be a variant of this rare entity, whose early diagnosis is important, as surgical stabilisation of the spine is required.

Imagerie de l’ischémie périnatale

L’echographie transfontanellaire permet une exploration encephalique aisee et met bien en evidence les hemorragies et/ou dilatations ventriculaires. L’imagerie par resonance magnetique (IRM) est toutefois la modalite d’imagerie de choix des pathologies encephaliques neonatales, particulierement en cas d’ischemie ou d’anoxo-ischemie. Chez le nouveau-ne a terme, accident vasculaire cerebral (AVC) et encephalopathie anoxo-ischemique (EAI) peuvent survenir. L’AVC se revele generalement par des convulsions hemicorporelles, au moins plusieurs heures apres la naissance et concerne le territoire sylvien. L’EAI lese principalement la substance grise : territoires jonctionnels, cortex cerebral (central notamment), noyaux gris centraux, tronc cerebral voire l’ensemble du cerveau. Chez le premature, on distingue les hemorragies sous-ependymaires, intraventriculaires et parenchymateuses (classification de Papile) de la leucomalacie periventriculaire, qui peut etre kystique ou petechiale.

In vivo assessment of experimental neonatal excitotoxic brain lesion with USPIO-enhanced MR imaging

Purpose:To assess the feasibility of magnetic resonance imaging (MRI) enhanced with ultrasmall superparamagnetic particles of iron oxide (USPIO) for assessing excitotoxic brain lesions in an experimental model of neonatal periventricular white matter (PWM) lesions.Materials and methods:Brain lesions were induced by intracerebral injection of ibotenate in 14 newborn rats. Pre- and post-USPIO T2-weighted MRI was performed in seven of them (group A) and in five control newborns (group C). In seven newborns with induced cerebral lesions, USPIO-enhanced MRI was not performed (group B). We compared the signal intensity of the lesion to the contralateral unaffected brain (lesion-to-brain contrast, LBC) and the lesion signal-to-noise ratio (SNR) before and after USPIO injection. MR imaging was correlated with histology.Results:USPIO injection significantly (P < 0.05) decreased LBC and SNR of brain lesion but induced no changes in normal controls. The densities of macrophages and iron-laden cells were higher on the lesion side than on the contralateral side (P < 0.05). Neither lesion size nor the surrounding macrophage infiltrate was significantly different between groups A and B.Conclusion:Post-USPIO T2-weighted MRI demonstrated negative enhancement of neonatal excitotoxic brain lesion. USPIO injection does not appear to exacerbate brain lesions.