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Background and Purpose: Predominant cerebellar involvement has not been previously reported as a common neuroradiologic feature in pediatric mitochondrial cytopathies. Here we report the neuroradiologic findings of predominant cerebellar volume loss in children with various mitochondrial disorders., Methods: A retrospective analysis of the medical records of 400 consecutive patients referred for evaluation of mitochondrial encephalomyopathies was performed. In 113 cases, definite diagnosis of mitochondrial disease was based on the modified adult criteria that include clinical, histologic, biochemical, functional, molecular, and metabolic parameters., Results: Predominant cerebellar volume loss with progressive cerebellar atrophy and, less often, cerebellar hypoplasia were found in a heterogeneous group of patients with mitochondrial disease that consisted of four patients with complex I deficiency; four patients with multiple respiratory chain deficiencies; two patients with combined complex I + III and II + III deficiencies, including one patient with partial coenzyme Q10 deficiency; three patients with complex II deficiency; two patients with complex IV deficiency; one patient with mitochondrial neurogastrointestinal encephalomyopathy; and two patients with mitochondrial encephalomyopathy, lactic acidosis, and strokes., Conclusion: Our retrospective study shows that isolated or predominant cerebellar involvement can be found in various respiratory chain defects or mitochondrial disorders expanding the classical neuroradiologic findings observed in mitochondrial encephalomyopathies. The diagnostic workup in patients with neuromuscular features whose brain MR imaging exhibits cerebellar volume loss should include the evaluation for mitochondrial encephalomyopathies.

Background and Purpose: Proton MR spectroscopy has demonstrated reduced levels of N-acetylaspartate (NAA) in normal-appearing occipital and frontal regions of patients with acute nonpenetrating traumatic brain injury (TBI). We studied the relationship of frontoparietal NAA, choline (Cho), and creatine (Cr) to test the hypothesis that reduction in NAA is predictive of cognitive outcome., Methods: Proton spectra were collected by using conventional 2D chemical shift imaging in five healthy children and seven children (6 weeks to 3 years) with severe (n=4), moderate (n=2), or mild (n=1) TBI. Spectra in the anterior and posterior regions of the left and right frontoparietal areas were averaged for analysis by using LCModel, with a phantom-established basis function, for quantification of NAA, Cho, and Cr concentrations. Intellectual function, expressive language, and arithmetic capability were measured within 4 months of imaging., Results: NAA/Cho concentration was lower in TBI patients than in control subjects, but no group differences were present for Cho or Cr. Hemispheric levels for NAA, Cho, and Cr were higher on the left than on the right, but we found no effect of region and no interactions. Cognition was lower in the TBI group than the control group and correlated with NAA levels. Left frontal Cho was also correlated with arithmetic scores, whereas Cr was not significantly correlated., Conclusion: NAA levels remain low after TBI and are related to cognitive function. Neurometabolite values are greater in the left frontoparietal region than in the right, and the left frontal Cho level is related to arithmetic ability.

Background and Purpose: Clinical validation of magnetization transfer (MT) imaging is important for investigating clinical disease and organization of normal brain function. We determined whether an in vivo quantitative measure sensitive to white matter is distributed in functionally important ways., Methods: Axial 1.5-T MR images with and those without MT were obtained. MT ratios (MTRs) were computed for 33 regions of interest (ROIs) in 27 healthy adults (aged 18-69 years) without evidence of cognitive or radiographic abnormalities. Three tests of reliability yielded coefficients above 0.97. MTRs for the whole brain, groups of structures, and individual ROIs were calculated. Low standard errors confirmed the consistency of the technique., Results: Age, education, sex, and hand dominance were not correlated with whole-brain MTR (mean = 37.35, SD = 1.25), but age was associated with the cerebellum and some lobes at a trend level. MTRs were as follows, in descending order: corpus callosum, cingulate, white matter, brain stem, subcortical nuclei, and cerebellum. MTRs were selectively higher in the prefrontal lobe versus the posterior frontal lobe and in the lateral temporal lobe versus medial temporal lobe. MTR was higher in the left hemisphere than in the right hemisphere for the whole brain, frontal and temporal lobes, and lenticular nuclei., Conclusion: MT imaging showed selective age, medial-lateral, and hemispheric differences, giving evidence of normal aging effects on the white matter in the absence of T2- weighted hyperintensities. These differences support neurocognitive theories of the organization of brain function. MT imaging appears to be a robust technique for use in cognitive neuroscience.

The impact of traumatic brain injury (TBI) on working memory (WM) was studied in 144 children (79 with mild, 23 with moderate, and 42 with severe injuries) who underwent magnetic resonance imaging (MRI) at 3 months and were tested at baseline and at 3, 6, 12, and 24 months postinjury. An n-back WM task for letter identity was administered with memory load ranging from 1- to 3-back and a 0-back condition. A TBI Severity x Quadratic Tune interaction showed that net percentage correct (correct detections of targets minus false alarms) was significantly lower in severe than in mild TBI groups. The Left Frontal Lesions x Age interaction approached significance. Mechanisms mediating late decline in WM and the effects of left frontal lesions are discussed.

Torticollis is a common condition presenting to the general or pediatric orthopedist. We describe the case of a child with severe torticollis caused by a hereditary unilateral absence of the sternocleidomastoid and trapezius muscles. Both his father and paternal grandfather had a forme fruste, with similar but milder findings. Electromyography and cross-sectional imaging were valuable in making the diagnosis. We believe this is the first reported case of hereditary unilateral muscle aplasia presenting as torticollis in an infant.

The risk of stroke in sickle cell disease (SCD) may be influenced by either genetic or environmental factors. Elevated blood flow velocity in the large cerebral arteries, detected by transcranial Doppler (TCD) ultrasonography, predicts an increased stroke risk in children with SCD. We undertook this study to investigate the possibility of a familial predisposition to elevated cerebral blood flow velocity, a surrogate marker for stroke risk. We analysed the results of TCD studies performed on 63 children from 29 families that had more than one child with SCD. We assessed the association of elevated cerebral blood flow velocity with sibling TCD results as well as age and haemoglobin level, which are factors known to affect cerebral blood flow velocity. Positive or negative TCD results were highly correlated between family members (r = 0.61). The presence of a sibling with a positive TCD result was significantly associated with an elevated cerebral blood flow velocity in other siblings with SCD (odds ratio = 50.7, 95% confidence interval 10.1-253.7, P < 0.001). Furthermore, children who had a sibling with a positive TCD result had a significantly higher TCD velocity than children with SCD but without a sibling who were matched for age, sex, genotype and haemoglobin level. Our results are consistent with a familial predisposition to cerebral vasculopathy in SCD.