Children and adolescents

Michael Glynn MA Medico FRCP FHEA , in Hutchison's Clinical Methods , 2018

Head circumference

In infants nether the age of 2 years, the caput circumference is a skillful proxy for linear growth and a much more than reliable measurement than height or length. The standard measurement is the largest occipitofrontal circumference out of three using a paper record. As applies to elevation and weight, it is the rate of growth rather than a one-off abnormal value which usually gives cause for concern. Some causes of microcephaly and macrocephaly are listed in Box vi.10. Rather than using a chart showing the head circumference alone, it is more useful to utilise one that combines caput circumference and length and weight percentiles, so that the proportions of each individual child can be compared.

CHILDREN | Stages of Evolution and Growth

H. Hayden-Wade , L.Chiliad. Leslie , in Encyclopedia of Forensic and Legal Medicine, 2005

Head circumference

Clinically, head circumference is routinely measured during the first 2 years of life. During this time, the brain is growing immensely and the open sutures between the bones of the skull are closing. Between nascency and ii months, the boilerplate head growth in 1 week is 0.50  cm (0.20   in.), so slows to 0.25   cm (0.10   in.) betwixt 2 and 6 months. The average total caput circumference growth from birth to 3 months is equal to 5   cm (ane.97   in.), and four   cm (1.57   in.) average from 3 to six months. This tendency continues to decelerate across the first year; between 6 and 9 months, head circumference increases 2   cm (0.79   in.) and between 9 and 12 months, head circumference increases but one   cm (0.39   in.), approximately.

During the second twelvemonth, a child'southward caput growth slows (i.east., ii.5   cm or 1   in., for the entire twelvemonth), although attainment of 90% of adult head size occurs by the cease of that twelvemonth.

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Nifty–Walker Syndrome

S.Southward. Kollias , in Encyclopedia of the Neurological Sciences (Second Edition), 2014

Pathological Findings

The head circumference is increased with a dolichocephalic configuration and preferentially widened lambdoid sutures. The posterior fossa is markedly expanded and presents erosive scalloping of the posterior surfaces of the petrous pyramids and the occipital squama secondary to cerebrospinal fluid (CSF) pulsations. The tentorium has a high and well-nigh vertical attachment, whereas the transverse sinuses and torcula are abnormally elevated along the parietal bone. The angle formed past the junction of the straight sinus with the superior sagittal sinus increases from a normal acute bending of approximately 50–75° to an obtuse angle of approximately ninety–150°. The falx cerebelli is absent-minded and the incisura is inclined vertically and wider than normal. The vermis is completely absent-minded in approximately 25% of cases. The rest testify partial aplasia of the posterior vermis, with the rest of the superior vermis being rotated anterosuperiorly and reflected upwards where it blends with the membranous roof of the cystic fourth ventricle ( Figure 1).

Effigy one. Magnetic resonance imaging (MRI) of an eight-month-quondam child with the characteristic neuroradiological findings of DWS and associated hydrocephalus. (a) Midsagittal T1-weighted MRI demonstrates the caudally hypoplastic vermis with its remainder rostral portion existence rotated and displaced anterosuperiorly past the enlarged quaternary ventricle, which expands into a large posterior fossa cyst. The tentorium and torcula take failed to descent to their normal anatomical position. The brainstem is compressed anteriorly and the occiput is thinned with a posterior bulging. In this case, the corpus callosum is intact but compressed by the dilated ventricles. (b) Axial T2-weighted image shows the direct advice of the inductive quaternary ventricle with the retrocerebellar cyst and the hypoplastic cerebellar hemispheres compressed inductive against the posterior surface of the petrous pyramids. Dilated temporal horns of the lateral ventricles from the associated hydrocephalus.

The diaphanous roof membrane is fastened laterally to the cerebellar hemispheres and caudally to the medulla oblongata. The DW cyst is actually the distended fourth ventricle that balloons posteriorly backside the hypoplastic and laterally displaced cerebellar hemispheres. This is ofttimes enormously dilated, sometimes herniating upwards through the tentorial hiatus toward the splenium of the corpus callosum. Histologically, information technology comprises iii layers. The inner layer is ependyma, which is continuous with the ependyma lining the wall of the fourth ventricle. The outer layer is pia, which is located around the cyst and is continuous with the pia forth the medial and posterior surfaces of the cerebellar hemispheres. The intermediate layer includes neuroglial tissue and cerebellar remnants that would have normally formed the missing inferior vermis and medial portions of the cerebellar hemispheres. Calcification of this tissue may be present in approximately 7% of cases. The choroid plexus is abnormally positioned in the lateral recesses bordering the caudal insertion of the cyst at the medulla and may be entirely absent in twoscore% of cases.

The patency of the 4th ventricle outlet foramina has been much debated, merely in a bulk of cases they are patent, assuasive communication betwixt the fourth ventricle and the subarachnoid space. The cyst bulges confronting the arachnoid and dura that line the inner table of the occipital os, compressing the subarachnoid infinite that would have unremarkably become cisterna magna. This space becomes visible only when shunting of the cyst collapses the cyst wall abroad from the occipital bone or when contrast is introduced into the subarachnoid space. The cerebellar hemispheres are hypoplastic and displaced anterolaterally against the petrous pyramids. The brainstem appears modest every bit a effect of hypoplasia and compression by the 4th ventricular cyst. The aqueduct may be patent, narrowed, or occluded.

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Social Cerebral Neuroscience, Cognitive Neuroscience, Clinical Brain Mapping

C.S. Allely , ... C. Gillberg , in Brain Mapping, 2015

Total Brain Volume and Cerebral Lobes with MRI

Studies investigating head circumference (HC) and MRI brain volume advise that in the first year of life, there exists a critical period of aberrant total encephalon growth that subsequently leads to an enlargement in early childhood, which tin sometimes persist into adulthood ( Courchesne et al., 2001; Hazlett et al., 2005; Schumann et al., 2010). An aberrant trajectory of growth of the amygdala is also found in MRI studies of individuals with ASD, with amygdala enlargement found even at two years of age (i.e., Mosconi et al., 2009). It is unclear whether this enlargement persists into adulthood (see Amaral et al., 2008, for review). Cortical thickness in adults with ASD has been investigated by numerous MRI studies with inconsistent findings. Hadjikhani, Joseph, Snyder, and Tager-Flusberg (2006) reported discrete locations throughout the frontal, parietal, and temporal lobes showing evidence of cortical thinning. Other studies take plant increased cortical thickness in the temporal lobes (i.e., Hardan, Muddasani, Vemulapalli, Keshavan, & Minshew, 2006; Raznahan et al., 2009). Another report found increased cortical thickness in the temporal and occipital lobes with relative decreases in cortical thickness in the frontal and parietal lobes (Ecker, Marquand, Mourão-Miranda, Johnston, Daly, et al., 2010; Raznahan et al., 2009).

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Pediatric Neurology Role I

Sandrine Passemard , ... Alain Verloes , in Handbook of Clinical Neurology, 2013

Abstract

True microcephaly (caput circumference ≤  –   3   SD), either master (present at birth) or secondary (of postnatal onset) results from an imbalance between progenitor jail cell product and cell death that lead to a reduced number of neuronal and glial cells within the brain, resulting in reduced brain growth. Chief non-syndromal microcephalies are recessive disorders resulting from aberrant command of mitotic spindle and prison cell cycle kinetics in progenitor cells. Microcephaly is likewise a frequent sign of defects in DNA double- and/or single-strand break repair and in nucleotide excision repair, in which information technology often is associated with full general growth impairment. In these etiologies, cognitive functions are reasonably well preserved despite astringent reduction in brain volume. Neuronal migration defects are often associated with secondary microcephaly, every bit are anomalies of telencephalic cleavage. Secondary microcephalies are often associated with increased neuronal death, and tin can be associated with metabolic disorders such as serine deficiency or thiamine pyrophosphate transporter deficiency. Microcephaly can exist associated with hundreds of syndromal congenital anomalies, including many chromosomal disorders. Genetic etiologies of developmental microcephalies are reviewed.

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Pediatric Neurology Part Iii

Marie-Cécile Nassogne , Lucie Hertz-Pannier , in Handbook of Clinical Neurology, 2013

Microcephaly associated with inherited metabolic diseases

Microcephaly is usually defined as a caput circumference (HC) more two standard deviations (SD) below the hateful for age and gender. Microcephaly could exist a sign of encephalon destruction consecutive to an acute metabolic decompensation in IEM of intermediate metabolism: amino and organic acid disorders and urea wheel defects. Metabolic disorders rarely nowadays with nonsyndromic congenital microcephaly, with three exceptions: maternal phenylketonuria, in which the fetal brain is exposed to toxic levels of phenylalanine during pregnancy; phosphoglycerate dehydrogenase deficiency, a treatable disorder of L-serine biosynthesis; and Amish lethal microcephaly, which is associated with 2-ketoglutaric aciduria. Metabolic testing should be considered when the following items are present: a parental history of consanguinity, a family unit history of similar symptoms in relatives, episodic symptoms (seizures, clutter, airsickness, encephalopathy), developmental regression, extracranial organ failure, or specific findings on neuroimaging. Built defects of glycosylation, mitochondrial and peroxisomal disorders, Menkes disease, sulfite oxidase deficiency, and glucose transporter defect are the almost frequent metabolic causes.

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Megalencephaly

B. Berg , in Encyclopedia of the Neurological Sciences (Second Edition), 2014

Abstract

Megalencephaly is a condition in which the patient's caput circumference exceeds the mean by at least two standard deviations adapted for age, sex, and race. It is a descriptive term referring to an abnormally big caput rather than any specific diagnosis. It is an important physical sign suggesting a multifariousness of disease states, each of which must be excluded by neurological evaluation of the patient. The head circumference may exist abnormally large at nativity, although in some cases it is inside normal limits at nativity just to later increase at a rate greater than normal for head circumference growth. Some megalencephalic persons are otherwise normal and have normal family members with megalencepaly. At that place is no known genetic basis for this familial megalencephaly.

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Autism

Thousand. Dawson , Thou. Murias , in Encyclopedia of Neuroscience, 2009

Cerebral Enlargement

In the first two years of life, head circumference (HC) measurements accurately reverberate brain volumes. At nascence, HC measurements in children with autism are non atypically large; all the same, by adulthood, approximately twenty% of individuals with autism showroom larger than average HC. A catamenia of exceptionally rapid head growth occurs during the beginning year of life in children who are later diagnosed with autism, equally well every bit in many younger siblings of children with autism who are at risk for the disorder. Patterns of HC trajectory appear to be an early risk marker for the development of ASD symptoms. Increased rate of growth may index abnormal processes during early on development, and may precede the onset of autism-specific symptoms. HC is hands measured in the class of routine check-ups and is potentially useful equally an early biological risk marker for ASD.

Imaging studies take consistently constitute increases in overall brain volumes in children and adults with ASD. Results from a longitudinal imaging report of brain growth demonstrate that the cerebral enlargement found in ASD children at iii–four   years erstwhile were no longer significant at vi–7   years of age, compared to age-matched developmentally delayed and typically developing children. Even so, within individuals, this growth curve can be quite variable. Alterations in early cellular developmental processes, such as failure of apoptosis or synaptic pruning, have been hypothesized to account for early cerebral enlargement, but recent longitudinal magnetic resonance spectroscopic imaging (MRI) findings of brain chemic changes in ASD children take failed to back up such mechanisms.

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Neurocutaneous Syndromes

Andreea Nissenkorn , Bruria Ben-Zeev , in Handbook of Clinical Neurology, 2015

Head circumference

A surprising feature in children with AT is small head circumference, with microcephaly in 17% of the patients (versus 3% of the full general population) ( Nissenkorn et al., 2011). Microcephaly is proportionate to meridian and weight and is caused postnatally.

Many genes related to DNA repair are known to cause microcephaly; intense activation of Deoxyribonucleic acid repair processes is taking place during neurogenesis, peculiarly during the intrauterine process of division of periventricular progenitor cells into neurons (O'Driscoll and Jeggo, 2008). Examples of such disorders presenting with microcephaly at birth are defects in the ATR and NBS1 genes, which are closely related to ATM pathway (Antoccia et al., 2006; O'Driscoll and Jeggo, 2008; Chrzanowska et al., 2012).

However, in AT microcephaly is acquired subsequently the second twelvemonth of life, therefore it is more plausible that information technology is related to processes that affect neurite growth and synaptogenesis (Nissenkorn et al., 2011). It is possible that a cytoplasmic ATM defect has a part in synaptic transmission through mTOR, a fundamental regulator of neural cell size, dendritic arborization, and brain size (Shen and Houghton, 2013).

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Neurocutaneous Syndromes

Jessica Mester , Charis Eng , in Handbook of Clinical Neurology, 2015

Central nervous system

Macrocephaly . Approximately 94% of people with PHTS take head circumferences which measure  >   2 standard deviations from the norm for historic period and gender. On average, head circumference measured +   iv.89 standard deviations to a higher place the mean for children. Adult men and women average head circumference measured 62.8   cm and lx.0   cm, respectively (Mester et al., 2011). Instance reports and minor imaging series have found the enlarged head circumference in PHTS is due to overgrowth of encephalon tissues as opposed to hydrocephalus (Padberg et al., 1991; Eng et al., 1994; Lok et al., 2005).

Autism/developmental delay. PTEN mutations take been identified in 10–17% of children with both macrocephaly and autism (Butler et al., 2005; Buxbaum et al., 2007; Varga et al., 2009; McBride et al., 2010). The range of developmental impact varies widely, with some patients having no developmental issues and normal to superior IQ whereas others are classified as severely impacted past autism with or without mental retardation (Lachlan et al., 2007; Busch et al., 2013).

Lhermitte–Duclos illness (LDD). In a case written report describing two unrelated patients with both LDD and CS, the authors surmised that the co-occurrence of two seemingly rare atmospheric condition was owed to more than gamble alone (Padberg et al., 1991). Several subsequent instance reports and series accept identified LDD in patients with PHTS (Eng et al., 1994; Zhou et al., 2003). Germline or somatic PTEN mutations have been identified in a majority of LDD tumors (Zhou et al., 2003). Fortunately, LDD seems to be an uncommon manifestation of PHTS, with one recent European series finding this diagnosis in 9% of cases (Nieuwenhuis et al., 2014).

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