Michael Kean

Clinical and neuroradiologic features of acute disseminated encephalomyelitis in children

Objective: To identify the clinical and neuroradiologic features of acute disseminated encephalomyelitis (ADEM) in childhood. Methods: A retrospective review was conducted of the medical records and MRI of children who presented to the Royal Children’s Hospital in Melbourne with ADEM between January 1993 and December 1998. Results: Of the 31 patients included in this study, 22 (71%) experienced a prodromal illness. Two patients (6%) had received hepatitis B vaccine 3 to 6 weeks before developing their illness. Symptoms and signs typically evolved over several days. Ataxia was the most common presenting feature, occurring in 20 patients (65%). MRI findings were variable, but lesions were most commonly seen bilaterally and asymmetrically in the frontal and parietal lobes. The authors found a high incidence of the corpus callosal and periventricular changes more typically associated with MS, but they also found a high rate of deep gray matter involvement (61% of patients). The use of high-dose IV methylprednisolone was usually associated with rapid recovery. Eighty-one percent of patients recovered completely, with only mild sequelae recorded in the remaining children. Conclusion: In the absence of a biological marker, the distinction between ADEM and MS cannot be made with certainty at the time of first presentation, but the authors suggest that a viral prodrome, early-onset ataxia, high lesion load on MRI, involvement of the deep gray matter, and absence of oligoclonal bands are more indicative of ADEM.

In vivo identification of human cortical areas using high-resolution MRI: An approach to cerebral structure–function correlation

Understanding the relationship between the structural and functional organization of the human brain is one of the most important goals of neuroscience. Individual variability in brain structure means that it is essential to obtain this information from the same subject. To date, this has been almost impossible. Even though noninvasive functional imaging techniques such as functional MRI (fMRI) are now commonplace, there is no complementary noninvasive structural technique. We present an in vivo method of examining the detailed neuroanatomy of any individual, which can then be correlated with that individuals own functional results. This method utilizes high-resolution structural MRI to identify distinct cortical regions based on cortical lamination structure. We demonstrate that the observed MR lamination patterns relate to myeloarchitecture through a correlation of histology with MRI. In vivo high-resolution MRI studies identify striate cortex, as well as visual area V5, in four individuals, as defined by using fMRI. The anatomical identification of a cortical area (V5/MT) outside of striate cortex is a significant advance, proving it possible to identify extra-striate cortical areas and demonstrating that in vivo structural mapping of the human cerebral cortex is possible.

Clinical and imaging features of cortical malformations in childhood

Objective: To determine the types, relative frequencies, clinical features, and MRI characteristics of malformations of cortical development (MCD) occurring in a cohort of children referred to a tertiary pediatric center. Methods: Original MR images were reviewed by two investigators, who were blinded to clinical details, to determine the elemental imaging features of each malformation and to label these malformations according to an existing system of classification. Clinical information was collected by a review of hospital records. Results: A total of 109 children with MCD were identified. There were 58 boys and 51 girls, age 8 days to 18 years at initial imaging (mean age, 5 years). Seizures were present in 75%, developmental delay or intellectual disability in 68%, abnormal neurologic findings in 48%, and congenital anomalies apart from the CNS malformation in 18%. The main malformations identified were heterotopic gray matter (19%), cortical tubers (17%), focal cortical dysplasia (16%), polymicrogyria (16%), agyria/pachygyria (15%), schizencephaly/cleft (5%), transmantle dysplasia (5%), and hemimegalencephaly (4%). Eight patients had features of more than one malformation. Most lesions were multilobar (47%), with the frontal lobe being the most common lobe involved (78%). A total of 68% of patients had other cerebral malformations including ventricular dilatation or dysmorphism (46%) and abnormalities of the corpus callosum (29%). Conclusions: This study illustrates the spectrum of MCD in a pediatric cohort and highlights some of the differences between pediatric and adult patients. Patients with MCD presenting in childhood have a wider spectrum of malformations and more varied, often more severe, clinical manifestations. The lesions are frequently multifocal or generalized and many are associated with noncortical developmental brain anomalies.

Apparent Diffusion Coefficient in the Posterior Limb of the Internal Capsule Predicts Outcome After Perinatal Asphyxia

Objective. Predicting long-term outcome in infants with hypoxic-ischemic encephalopathy (HIE) is a difficult task. Magnetic resonance imaging, particularly diffusion imaging, holds promise in this regard as it is more sensitive to brain injury than any other available imaging modality. Previous studies have suggested that abnormal signal intensity in the posterior limb of the internal capsule (PLIC), detectable on inversion-recovery T1-weighted imaging, is a strong predictor of outcome. The aim of this study was to assess the relationship between apparent diffusion coefficient (ADC) values from the PLIC, measured by diffusion imaging, and neuromotor outcome in term infants with HIE. Methods. Twenty-eight term infants with a clinical diagnosis of HIE underwent magnetic resonance imaging as soon as practicable after birth (mean age: 5.6 days), including diffusion-weighted imaging, from which ADC values in the PLIC were measured. Motor outcome was assessed in 12 of 16 survivors. Results. The ADC value in the PLIC was significantly associated with survival in term infants with HIE. For survivors, the mean ADC value in the PLIC was 0.89 ± 0.17 μm2/ms, whereas the mean ADC value for nonsurvivors was 0.75 ± 0.17 μm2/ms (t = 2.25). Among survivors, the ADC value in the PLIC was also associated with neuromotor outcome (F = 5.60). Conclusion. The ADC value in the PLIC is an indicator of ischemic injury and may be of use as an objective prognostic marker for infants with HIE.

Detecting Traumatic Brain Lesions in Children: CT versus MRI versus Susceptibility Weighted Imaging (SWI)

Cranial CT scans are at the center of decision making in brain injuries in children because of their speed and ability to detect surgically relevant lesions. However, alternative techniques, such as conventional MRI may have advantages in terms of radiation exposure and sensitivity to detect brain injury. Susceptibility-weighted imaging (SWI), a relatively novel MRI sequence, shows promise in terms of its sensitivity in detecting hemorrhagic lesions; however, its clinical potential remains uncertain. In this observational study of children (5-16 years of age) with traumatic brain injury (TBI) at a tertiary pediatric emergency department (ED) we compared the ability of detecting traumatic brain lesions on acute CT and MRI/SWI ∼ 5 weeks post-injury based on detecting the presence or absence, extent, and type of traumatic brain lesions. We analyzed the results of 76 patients (53 male) after TBI (mean age 10.24 ± 2.50 years, range 5.75-14.67 years). Glasgow Coma Score was 13-15 in 54 patients (71%), 9-12 in 13 patients (17%) and <8 in 9 patients (12%). CTs were completed in the ED; MRI and SWI were completed at a mean of 36.11 ± 15.75 days post-injury. Detection of any lesions occurred on CT scan in 68%, on MRI in 54%, and on SWI in 86% of cases, and SWI detected additional lesions 30% of the time compared to CT and MRI. SWI may be more sensitive in detecting traumatic lesions than CT or MRI. This may be important for the ongoing management of TBIs and their prognosis.

fMRI Lateralization of Expressive Language in Children with Cerebral Lesions

Summary:  Purpose: Lateralization of language function is crucial to the planning of surgery in children with frontal or temporal lobe lesions. We examined the utility of functional magnetic resonance imaging (fMRI) as a determinant of lateralization of expressive language in children with cerebral lesions.

Hippocampus, amygdala and global brain changes 10 years after childhood traumatic brain injury.

Traumatic brain injury (TBI) in children results in damage to the developing brain, particularly in severely injured individuals. Little is known, however, of the long‐term structural aspects of the brain following childhood TBI. This study investigated the integrity of the brain 10 years post‐TBI using magnetic resonance imaging volumetrics in a sample of 49 participants with mild, moderate and severe TBI, evaluated against a normative sample of 20 individuals from a pediatric database with comparable age and gender distribution. Structural integrity was investigated in gray and white matter, and by manually segmenting two regions of interest (hippocampus, amygdala), potentially vulnerable to the effects of childhood TBI. The results indicate that more severe injuries caused a reduction in gray and white brain matter, while all TBI severity levels resulted in increased volumes of cerebrospinal fluid and smaller hippocampal volumes. In addition, enlarged amygdala volumes were detected in severely injured patients compared to their mild and moderate counterparts, suggesting that childhood TBI may disrupt the development of certain brain regions through diffuse pathological changes. The findings highlight the lasting impact of childhood TBI on the brain and the importance of monitoring brain structure in the long‐term after early injury.

Posterior parietal cortex control of reach-to-grasp movements in humans.

The aim of the present study was to ascertain the neural correlates for the integration of visual information with the control of the reach‐to‐grasp action in the healthy human brain. Nine adult subjects (18–38 years; four females and five males) were scanned using functional magnetic resonance imaging while reaching‐to‐grasp a three‐dimensional target. Results demonstrated differential activation of the parietal cortices according to the number of potential targets to be taken into account before movement initiation and the variability of target location. Comparing conditions where a target object that can appear at an unpredictable location with conditions where the target object appears at a predictable location revealed activations in the left superior parietal lobule, the left parieto‐occipital sulcus and the right intraparietal sulcus. Results are discussed in terms of visual selective attention and action planning.

Language lateralization correlates with verbal memory performance in children with focal epilepsy

Purpose:  Assessment of language dominance with functional magnetic resonance imaging (fMRI) and neuropsychological evaluation is often used prior to epilepsy surgery. This study explores whether language lateralization and cognitive performance are systematically related in young patients with focal epilepsy.

The surgically remediable syndrome of epilepsy associated with bottom-of-sulcus dysplasia

Objective: To determine clinical and EEG features that might help identify patients with epilepsy harboring small, intrinsically epileptogenic, surgically treatable, bottom-of-sulcus dysplasias (BOSDs). Methods: Retrospective review of clinical records, EEG, MRI, and histopathology in 32 patients with drug-resistant epilepsy and MRI-positive (72% 3.0 tesla), pathologically proven (type 2B cortical dysplasia) BOSDs operated at our centers during 2005–2013. Results: Localization of BOSDs was frontal in 19, insula in 5, parietal in 5, and temporal in 3, on the convexity or interhemispheric surfaces. BOSDs were missed on initial MRI at our centers in 22% of patients. Patients presented with focal seizures during infancy in 9, preschool years in 15, and school years in 8 (median age 5 years). Seizures were stereotyped, predominantly nocturnal, and typically nonconvulsive, with semiology referable to the fronto-central or perisylvian regions. Seizures occurred at high frequency during active periods, but often went into prolonged remission with carbamazepine or phenytoin. Intellect was normal or borderline, except in patients with seizure onset during infancy. Scalp EEG frequently revealed localized interictal epileptiform discharges and ictal rhythms. Patients underwent lesionectomy (median age 14 years) guided by electrocorticography and MRI, with prior intracranial EEG monitoring in only one patient. Twenty-eight patients (88%) became seizure-free, and 20 discontinued antiepileptic medication (median follow-up 4.1 years). Conclusions: In patients with cryptogenic focal epilepsy, this clinical presentation and course should prompt review of or repeat MRI, looking for a BOSD in the frontal, parietal, or insula cortex. If a BOSD is identified, the patient might be considered for single-stage lesionectomy.