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Isolated developmental delay (IDD) is a common disorder in preschool and school-age children. Conventional magnetic resonance imaging (MRI) usually does not disclose abnormalities, but a myelination delay is suspected as causative or associated factor. N-acetyl-aspartate is a surrogate marker of neuronal integrity but also of axonal integrity. The goal of our study is to determine whether magnetic resonance spectroscopy (MRS) is able to detect alterations in the white matter supporting the hypothesis of delayed myelination in children with IDD and normal MRI.In this cross-sectional study, we enrolled 12 consecutive children meeting the criteria if IDD and aged between 3 and 12 years (mean 7.25 years) and 11 healthy children as control group (mean age 7.18, range 3-12 years) on whom we performed conventional MRI and MRS. We did not include children with abnormal MRI. Single voxel (8 cm(3)) was placed in the white matter of the left centrum semiovale. The mode of acquisition was probe-p (PRESS technique) with a TR of 2500 milliseconds and a TE of 30 milliseconds. We measured the metabolite concentration of n-acetyl-aspartate (NAA), choline (Ch), creatine (Cr) y myo-inositol (mI), and ratios of NAA, Ch, and mI to creatine.In children with IDD, we found a significant decrease of the following ratios: NAA/Cr (P.016), NAA/Ch (P.026), and NAA/mI (P.023) in relation to controls. The mean NAA/Cr ratio in IDD children was 1.92 (SD 0.14), and in controls it was 2.09 (SD 0.14); t = 2.62, fd (freedom degrees) = 21, P.016. No differences were seen in the remaining ratios.The lower NAA/Cr ratio in children with IDD in relation to controls may be a promising marker of this disorder and supports the hypothesis of delayed myelination. MRS can provide important information in children with neurodevelopmental disorders.

N-acetylaspartate (NAA) contributes to the most prominent signal in proton magnetic resonance spectroscopy (1H-MRS) of the adult human brain. We report the absence of NAA in the brain of a 3-year-old child with neurodevelopmental retardation and moderately delayed myelination. Since normal concentration of NAA in body fluids is hardly detectable, 1H-MRS is a noninvasive technique for identifying neurometabolic diseases with absent NAA. This report puts NAA as a neuronal marker to question. Ann Neurol 2001;49:518–521

Fukuyama-type congenital muscular dystrophy (FCMD) is characterized by congenital muscular dystrophy and associated with neuropathological anomalies. However, the issue of whether the radiological findings of white-matter lesions represent delayed myelination, demyelination or other problems remains controversial. We present serial radiological findings, including MR spectroscopy (MRS), in a child with FCMD. These findings indicate a correlation between the imaging abnormalities and the choline/creatine ratio, suggesting the possible usefulness of MRS in addition to MRI for following FCMD patients.

Whether the pathologic origin of white matter lesions in Fukuyama type of congenital muscular dystrophy (FCMD) is delayed myelination or dysmyelination is a controversial issue. This study investigated pathologic distribution in white matter with heavily T 2 -weighted images using fluid-attenuated inversion recovery (FLAIR) pulse sequence. For detection of abnormal white matter lesions, FLAIR images were approximately twice as sensitive as T 2 -weighted images and five times as sensitive as T 1 -weighted images of spin echo sequence. The distribution of the white matter lesions was disseminated and not correlated with cortical disarrangement. The distribution was not consistent with delayed myelination. These findings support the evidence found using in vitro proton-NMR spectroscopy that the pathologic origin of white matter lesions is dysmyelination. When conventional magnetic resonance imaging is used, masked white matter lesions are easy to misidentify as delayed myelination instead of disseminated developmental dysmyelination. The lesions in the white matter of FCMD are masked because of brain development.

We report here on a Japanese male infant with megalocornea-mental retardation (MMR) syndrome. He had megalocornea (corneal diameter: 13 mm) without glaucoma, developmental retardation, hypotonia, frontal bossing, high-arched palate, carp-like mouth, micrognathia, and delayed myelination. He seems to be included in Verloes type of the MMR syndrome.

A 3.5-year-old girl with tyrosinemia is reported. A computed tomography scan of the abdomen revealed multiple hepatic nodules. Brain magnetic resonance imaging revealed bilateral high-signal changes confined to the globus pallidus on T2-weighted images. Globus pallidus lesions likely represented neuropathologic changes such as astocytosis, delayed myelination, and status spongiosus (myelin splitting and vacuolation).

Background Methylmalonate semialdehyde dehydrogenase (MMSDH) deficiency is a rare autosomal recessive disorder with varied metabolite abnormalities, including accumulation of 3-hydroxyisobutyric, 3-hydroxypropionic, 3-aminoisobutyric and methylmalonic acids, as well as β-alanine. Existing reports describe a highly variable clinical and biochemical phenotype, which can make diagnosis a challenge. To date, only three reported cases have been confirmed at the molecular level, through identification of homozygous mutations in ALDH6A1, the gene encoding MMSDH. Confirmation by enzyme assay has until now not been possible, due to the extreme instability of the enzyme substrate. Methods and results We report a child with severe developmental delays, abnormal myelination on brain MRI, and transient/variable elevations in lactate, methylmalonic acid, 3-hydroxyisobutyric and 3-aminoisobutyric acids. Compound heterozygous mutations were identified by exome sequencing and confirmed by Sanger sequencing within exon 6 (c.514 T > C; p. Tyr172His) and exon 12 (c.1603C > T; p. Arg535Cys) of ALDH6A1. The resulting amino acid changes, both occurring in residues conserved among mammals, are predicted to be damaging at the protein level. Subsequent MMSDH enzyme assay demonstrated reduced activity in patient fibroblasts, measuring 2.5 standard deviations below the mean. Conclusions We present the fourth reported case of MMSDH deficiency with confirmation at the molecular level, and expand on what is already an extremely variable clinical and biochemical phenotype. Furthermore, this is the first report to demonstrate a corresponding reduction in MMSDH enzyme activity. This report illustrates the emerging utilization of whole exome sequencing and variant data filtering using clinical data as an early tool in the diagnosis of rare and variable conditions.

A finger lozalization task was used to investigate interhemispheric transfer of tactile information and the processing of sequential tactile information in 7- and 9-year-old “average” readers and 9-year-old reading disabled boys. The performance of the reading disabled group on interhemispheric transfer and sequential processing was comparable to or worse than the 7-year-old average readers. Significant correlations linked the reading disabled boys' performance on the finger localisation task with their reading skills, performance on perceptual/motor tasks and knowledge of order in the time domain. The results are interpreted in terms of delayed myelination of interhemispheric and intrahemispheric pathways in the reading disabled.

Magnetic resonance imaging (MRI) was used in high-risk infants to assess the myelination process and its relationship with neurologic outcome. The time period when delayed myelination is best detected by MRI was also studied. MRI was performed in 39 high-risk infants (i.e., preterm infants, infants with respiratory distress syndrome, or with neonatal convulsions and asphyxia). In 10 of 11 infants with normal development, MRI revealed a normal myelination pattern before 2 months of age, and in 11 of 13 infants after 2 months of age. Conversely, in infants with poor outcomes, MRI demonstrated delayed myelination patterns in only 1 of 4 infants before 2 months of age but in 9 of 11 infants after 2 monthes of age. In patients with poor outcomes, delayed myelination was found more frequently after rather than before 2 months of age. These findings demonstrate that delayed myelination detected by MRI is useful in predicting the neurologic outcome of high-risk infants, especially after 2 months of age.

The authors examined 15 patients with delayed myelination of the optic nerve and pseudo optic atrophy of Beauvieux. Three cases presented with albinism. In one patient the diagnosis of generalized hypomyelination of the brain was confirmed by the Nuclear Magnetic Resonance technique.The prognosis is relatively favourable. Follow-up examinations showed that in the majority of the patients the delay in myelination will be made good. Visual acuity could be measured in six patients and varied from 0.1 to 0.6.

We describe three patients with type A Niemann-Pick disease (NPD-A). NPD-A is an autosomal recessive neuronal storage disease classified among the sphingolipidoses, characterized by accumulation of sphingomyelin in various tissues and in the brain. Magnetic Resonance imaging (MRI) of our three patients showed a marked delay of myelination with frontal atrophy. Few descriptions of this MRI pattern of delayed myelination have been published to date.

Item does not contain fulltext Monitoring effects of a ketogenic diet in GLUT1 deficiency syndrome without seizures is difficult. Neuroimaging is considered uninformative. We report the case of a boy with neurodevelopmental delay, severe ataxia, an E54X-mutation in the SLC2A1 gene (previously GLUT1), and neuroimaging abnormalities indicative of delayed myelination. Six months on a ketogenic diet resulted in an improved high subcortical white matter signal on T2-weighted images and a reduced N-acetylaspartate/creatine ratio. We conclude that delayed subcortical myelination may occur in GLUT1 deficiency syndrome as a nonspecific finding reflecting developmental delay. In patients without seizures, cranial magnetic resonance imaging and magnetic resonance spectroscopy may prove useful tools to monitor the response to a ketogenic diet.

Two unrelated children and their siblings of Arab origin were diagnosed as having GM1 gangliosidosis on the basis of clinical features and markedly low levels of β-galactosidase. The T2-weighted magnetic resonance images of the brain revealed certain characteristic features, including delayed myelination and abnormal appearance of the subcortical white matter, internal capsule, and basal ganglia. Their mutation analysis showed two novel mutations, which have not been described in an Arabic population. ( J Child Neurol 2005;20:57—60).

Delayed acquisition of developmental motor and cognitive milestones is a common clinical expression of many etiological processes. Imaging exams of developmentally delayed children often show no structural brain alterations despite suspicion of brain maturation delay. MRI studies increasingly suggest that white matter myelination finely reflects the progression in functional brain maturation. In this volumetric MRI study, we sought to evaluate whether developmental delay in children with normal conventional MRI exams is associated with reduced myelinated white matter. A total of 100 children (mean age, 4.4 years) with developmental delay and 50 normally developing age-matched control children underwent 3-D MRI to measure the volume of myelinated white matter. Patients showed a significant reduction in the relative content of myelinated white matter (accounting for 19.8% of brain volume in patients and 21.4% in control subjects, P = 0.005). The observed difference was equivalent to a 3.2-year myelination delay. Although the whole hemispheres were invariably symmetrical, the volume of myelinated white matter was asymmetrical in 30% of patients and 10% of control subjects (P = 0.006). We conclude that volumetric assessment of white matter may reveal a reduction in brain myelination beyond early childhood in developmentally delayed children showing normal brain appearance. This finding further emphasizes the view of white matter myelination as an indicator of functional brain maturation.

Sandhoff's disease is a rare, genetic lysosomal storage disease leading to delayed myelination or demyelination. Although neuroimaging findings in this disease have been reported previously, magnetic resonance spectroscopy findings have not been reported. In this report, we present magnetic resonance imaging and magnetic resonance spectroscopy features of two cases with Sandhoff's disease. Magnetic resonance spectroscopy revealed findings indicating widespread demyelination in both cases and neuroaxonal loss and anaerobic metabolism in the second case. Magnetic resonance spectroscopy could provide useful information in the explanation of the clinical picture of cases with Sandhoff's disease. ( J Child Neurol 2003;18:425—428).

An etiologic evaluation of 86 patients with infantile spasms is presented and the place of cranial magnetic resonance imaging (MRI) findings within this spectrum is discussed. A total of 103 cranial MRIs, performed between 4 and 72 months of age, were analyzed and classified according to the etiologic and pathophysiologic aspects. Ninety-one percent of cases were diagnosed as symptomatic infantile spasms, and hypoxic-ischemic encephalopathy was the primary cause (30%). The most common involvement was thinning of the corpus callosum in 43 patients (50%), followed by dilation of cerebral ventricles in 32 (36%), delayed myelination in 23 (26.7%), lesions of diencephalic deep gray matter in 17 (19.7%), and enlargement of the subarachnoid space in 12 (14%). Thin corpus callosum and diffuse atrophy were changes mainly associated with hypoxic-ischemic encephalopathy, whereas delayed myelination seemed to be independent from a specific etiology. The results showed that cranial MRI may provide considerable information regarding not only the etiology but also the pathophysiology of infantile spasms. ( J Child Neurol 2003;18:241—246).

A Japanese boy with interstitial deletion of the long arm of chromosome 14, including band 14q31, is described. The characteristic dysmorphic facial features, such as dolichocephaly, bushy eyebrows, horizontal narrow palpebral fissures, long philtrum, etc, and mental and motor developmental delay were observed. Other characteristic clinical manifestations were anuresis and status nonepileptic myoclonia. The finding of delayed myelination of the cerebral white matter was observed on magnetic resonance examination, suggesting that an unknown factor related to myelination in the central nervous system might be localized in band 14q31. ( J Child Neurol 1999;14:756-758).

Research on children with Joubert syndrome has focused on brain structural abnormalities and associated clinical symptoms. The degree of developmental delay has not been objectively reported. We investigated the neurobehavioral development of children with Joubert syndrome through neurobehavioral assessment in the largest sample to date. Thirty-two parents of children with Joubert syndrome completed the Child Development Inventory and magnetic resonance imaging (MRI) data was gathered on 17 of these children. Results indicate that 94% were severely impaired according to the Child Development Inventory, with age being positively correlated with degree of neurobehavioral impairment. The average developmental age of our sample was 19 months (63% below chronological age). Severity of illness as measured by the General Development scale of the Child Development Inventory and severity of illness as measured by MRI (overall severity rating) did not yield consistent data regarding severity of the midbrain and cerebellar malformations. Similarly, markers of abnormal cerebral development such as cortical atrophy and delayed myelination were independent of severity of illness ratings on the Child Development Inventory. The degree of developmental delay in Joubert syndrome and the severity of gross central nervous system malformations appear independent. (J Child Neurol 1998;13:391-397).

Most SIDS deaths occur between 2 and 4 months of age. Neural transformations may be important in SIDS. Evidence of delayed myelination has been found in SIDS victims. However a simple neuro-developmental model is insufficient to explain SIDS. The age of death profile is reportedly similar for pre-term and full-term SIDS victims. Another developmental change is that IgG levels are lowest when SIDS risk peaks, and there is data linking SIDS and infections. Prone position may also increase risk. While a developmental model emphasizing neural transformation is useful, other factors affect risk also.

We present a girl with proven nonketotic hyperglycinaemia. The pathological findings on MRI were brain atrophy with thinning of the corpus callosum and delayed myelination of the cerebral hemispheres, particularly the parietal lobes.

Magnetic resonance imaging has been found to be useful in assessing brain myelination and provides information on brain maturation. The normal pattern of brain myelination conforms to a fixed sequence, with good pathologic and MRI correlation. Neuropathologic analysis of myelination has shown delayed central myelination in Down syndrome. Delayed myelination on MRI in Down syndrome has not previously been reported. We report a case of Down syndrome with a significant delay in myelination as demonstrated on MRI. This 18-month-old infant had brain myelination equivalent to that expected for an 11-month-old infant. To determine the relative incidence, extent of delayed myelination, and time for recovery to full myelination in Down syndrome, more cases require examination and assessment. Magnetic resonance imaging has the advantage of serial assessment of myelination during brain maturation. (J Child Neurol 1992;7:417-421).

We prospectively performed magnetic resonance imaging (MRI) studies during the neonatal period, and at 4 and 8 months of age, on 15 term infants with hypoxic-ischemic encephalopathy, and compared the results with their neurodevelopmental outcome at 18 months of age. Cerebral palsy developed in nine infants, two infants were classified as having abnormalities of fone and delayed motor milestones that were suggestive of cerebral palsy, and four infants were normal. Structural abnormalities, delayed myelination, or a combination of the two were detected with MRI at 8 months of age in all nine infants with later development of cerebral palsy. Three of the four normal infants and one infant with suggestive abnormallties had normal serial MRI findings. Each of the remaining two infants (one normal, one with suggestive abnormalities) had isolated persistent ventricular dilation on all three MRI studies. Our results suggest that 8 months appears to be the earllest time at which MRI findings correlate well with later adverse neurodevelopmental outcome in this population.

In this prospective study, 26 very preterm infants underwent magnetic resonance (MR) imaging of the brain at 44 weeks postmenstrual age (PMA) for staging of myelination. Neurodevelopmental outcome was assessed at 1 year of age. A significant correlation was demonstrated between delayed myelination and neurodevelopmental outcome (Chi 2 = 16.6, P = .01). A significant correlation was also found between ultrasound (US) findings in the neonatal period and outcome at 1 year (Chi 2 = 22.9, P = .03). To establish the criterion with the best predictive value, a multiple regression analysis was performed with periventricular-intraventricular hemorrhage, periventricular leukomalacia (PVL), and the stage of myelination at 44 weeks PMA as independent variables and neurodevelopmental outcome at 1 year of age as a dependent variable. Staging of myelination with MR imaging in the early postnatal period of very preterm infants had predictive value with regard to neurodevelopmental outcome. Detection of PVL with US, however, showed a better correlation with outcome, a result that seems to limit the potential role of MR imaging in this population for this purpose only.

To the Editor.— The study of Van de Bor et al1 appears to demonstrate differences in myelination between infants with and without periventricular leukomalacia (PVL). However, we feel that it does not demonstrate, as stated, that PVL causes delayed myelination, whereas periventricular-intraventricular hemorhage (PIVH) does not. Because the study group did not contain any survivors with intraparenchymal hemorrhage, caution must be used in stating that PIVH does not influence subsequent myelination. Myelination is a complex process which continues into adulthood.

Sixty-two computed tomographic (CT) scans of 36 patients with congenital muscular dystrophy of Fukuyama type (FCMD) were analysed. A low density area in the cerebral white matter was characteristic of FCMD and a special reference was made to the changes in the white matter low density. It was present in 15 patients out of 36 (42%) and frequently seen in the scans obtained on the younger patients; among 11 scans taken of patients between 1 and 2 years of age, 10 scans (91%) showed the white matter low density. Repeated CT scans were carried out on 26 of the 36 cases. Follow-up study revealed that the white matter low density areas were most apparent around the age of one year and decreased or disappeared at 2 or 3 years of age. From these observations, delayed myelination was suspected for the pathogenesis of the low density area found in FCMD.

SUMMARY The ultrastructure of the spinal cord in 2 cases of Border disease is described. The findings include delayed myelination, demyelination, cavitation of the myelin sheaths and extensive astrogliosis.

Myelinating mouse spinal cord fragments were cultured in Maximow assemblies. A variable interval after explanation they were exposed to low concentrations of serum from rabbits with experimental allergic encephalomyelitis (EAE). As a general rule, the longer they were kept under EAE serum, the more completely myelination was inhibited. If the experiments were made with low concentrations of EAE serum (about 1%), the number of myelinated cultures was proportional to the number of days by which the application of EAE-serum was delayed. If one worked with EAE-serum at higher concentrations (5%), the cultures on which the serum was applied with a delay from 1 to 5 days were practically completely inhibited in their myelination. If exposed from the 7th day onward only, nearly all of these cultures were able to myelinate and therefore showed myelin, when viewed on day 12 in vitro. If, however, they were left under the same concentrations of EAE-serum for another week, the myelin sheaths disappeared again without leaving any signs of myelin destruction. These cultures showed loose spirals of glial cytoplasma membranes around axons. Cultures in which the application of EAE-serum was delayed for 4–6 days showed differentiated oligodendrocytes and astrocytes, which was not the case in cultures inhibited from the explantation onward.

— Myelinating cultures of rat cerebellum were exposed to the branched-chain amino acids and their α-keto derivatives at concentrations found in maple syrup urine disease. Decreased-to-absent and delayed myelination was produced by α-keto-isocaproic acid at physiological levels. Injury to small cells, probably glia, was also noted. The other metabolites failed to produce any visible damage.

Publisher Summary This chapter discusses the characteristics of the neuropathy sample. The sample for the neuropathologic and epidemiologic studies reported was composed of fetuses and infants whose mothers were enrolled in the National Institute of Neurological Disorders and Stroke (NINCDS) Collaborative Perinatal Project; these infants died during the course of the project, were autopsied, and their neurologic material returned to the project in a useable condition. The male/female ratio and the racial proportions differed between the serially and nonserially sectioned groups. More live-born and stillborn male than female brains were nonserially sectioned. There was an almost equal sex distribution between the serially sectioned live-borns and nonserially sectioned stillborns. The controls for the perinatal telencephalic leukoencephalopathies characterized by two histologic features were infants who had neither histologic feature. The sample for study of delayed myelination differed considerably from these other samples: (1) no lower bound was set for gestational age, (2) the upper bound for the postnatal age was set at 7 days, and (3) the sample was confined to those newborns whose brains were embedded in celloidin and then serially sectioned.

Publisher Summary This chapter discusses the epidemiology of delayed myelination. Small head size and low brain weight are viewed as correlates of impaired neurologic function. Delayed myelination may also be a correlate of impaired function. In newborns, delayed evoked responses may be the most reliable quantitative indicator of delayed myelination. Preterm newborns, however, have illnesses that may have a more immediate effect on evoked responses than on the tinctorial properties of myelin. Thus, the greater sensitivity of evoked responses to metabolic stresses and the more rapid reversibility of their abnormalities may limit their usefulness in assessing myelination delays. A large body of data supports the hypothesis that the myelinating brain is vulnerable to the same factors that retard the growth of other organs. Growth retardation is best expressed by the combination of low birth weight and full-term gestational age variables. Factors such as maternal cigarette smoking, third-trimester uterine bleeding, and low maternal hematocrit explain and provide information about the setting for growth retardation.

The effects of biotin deprivation on ABER were studied in rat pups fed a diet that lacked this compound. Pregnant rats were either fed a normal rat diet (controls) or a special diet without biotin (Teklad, Harlan Sprague Dawley, Madison, WI). After weaning, the respective diets were continued in pups from each group. ABER was tested under chloral hydrate anesthesia (380 mg/kg) using clicks (100 μs, 5/s) and tone bursts (3‐ms duration, 1.5‐ms rise‐fall time at 2, 8, 16, and 32 kHz) presented free field with a driver suspended 8 cm above the vertex in the median plane. Responses were obtained using an active lead from the vertex with a reference electrode in the nose. Blood levels of biotin were measured using a microbiological assay. Animals on the biotin‐free diet showed alopecia and dry, scaly skin. There was no significant difference in ABER threshold in control versus experimental animals. However, there was a significantly longer brain‐stem transmission time (interpeak latencies from waves I to IV) in biotin‐deficient animals. The lowering of serum biotin in experimentals was confirmed by microbiologic assay. These findings suggest that biotin deficiency in the developing rat adversely affects auditory‐nerve and/or brain‐stem development. These effects could be mediated by a delayed myelination of these structures. [Work supported by Deafness Research Foundation.]