Microcephaly: a radiological review

A case-control study on the driving factors of childhood brain volume loss: What pediatricians must explore

BACKGROUND

The brain volume loss also known as brain atrophy is increasingly observed among children in the course of performing neuroimaging using CT scan and MRI brains. While severe forms of brain volume loss are frequently associated with neurocognitive changes due to effects on thought processing speed, reasoning and memory of children that eventually alter their general personality, most clinicians embark themselves in managing the neurological manifestations of brain atrophy in childhood and less is known regarding the offending factors responsible for developing pre-senile brain atrophy. It was therefore the goal of this study to explore the factors that drive the occurrence of childhood brain volume under the guidance of brain CT scan quantitative evaluation.

METHODS

This study was a case-control study involving 168 subjects with brain atrophy who were compared with 168 age and gender matched control subjects with normal brains on CT scan under the age of 18 years. All the children with brain CT scan were subjected to an intense review of their birth and medical history including laboratory investigation reports.

RESULTS

Results showed significant and influential risk factors for brain atrophy in varying trends among children including age between 14-17(OR = 1.1), male gender (OR = 1.9), birth outside facility (OR = 0.99), immaturity (OR = 1.04), malnutrition (OR = 0.97), head trauma (OR = 1.02), maternal alcoholism (OR = 1.0), antiepileptic drugs & convulsive disorders (OR = 1.0), radiation injury (OR = 1.06), space occupying lesions and ICP (OR = 1.01) and birth injury/asphyxia (OR = 1.02).

CONCLUSIONS

Pathological reduction of brain volume in childhood exhibits a steady trend with the increase in pediatric age, with space occupying lesions & intracranial pressure being the most profound causes of brain atrophy.

Genetic and Clinical Approach To Microcephaly: A 5-Year Single Center Experience

Microcephaly is a dysmorphic feature characterized by small head size more than two standard deviations below the mean for age, sex, and ethnicity. There are several etiological factors ranging from environmental toxins or infections to genetic disorders. We report clinical, radiological, and molecular genetic investigations of patients with microcephaly from a single center over 5-year period. There were 92 patients with a genetic diagnosis. Based on their genetic diagnosis, we grouped patients into three categories: (1) microcephaly with copy number variations (CNVs), (2) microcephaly with single gene disorders, and (3) microcephaly with aneuploidies. The most common category was aneuploidy in 59% of the patients, followed by single gene disorders in 23% of the patients and CNVs in 18% of the patients. We think that history and physical examination guide physicians to choose the most appropriate genetic testing to identify underlying diagnosis.

Congenital Zika Virus Infection: a Review with Emphasis on the Spectrum of Brain Abnormalities

Purpose of Review

In 2016, the World Health Organization declared the Zika virus (ZIKV) outbreak a Public Health Emergency of International Concern following a cluster of associated neurological disorders and neonatal malformations. Our aim is to review the clinical and neuroimaging findings seen in congenital Zika syndrome.

Recent Findings

ZIKV injures neural progenitor cells in the hippocampus, a brain region important for learning, memory, cognition, and emotion/stress response. Positron emission tomography has revealed global neuroinflammation in ZIKV infection in animal models.

Summary

Congenital Zika syndrome is associated with a spectrum of brain abnormalities, including microcephaly, parenchymal calcifications, malformations of cortical development and defective neuronal migration, corpus callosum abnormalities, ventriculomegaly, and brainstem and cerebellar abnormalities.

Continuous Intracranial Pressure Monitoring in 24 Microcephalic Children with Developmental Delay: A Significant Portion of Microcephalic Children with Developmental Delay Have High Intracranial Pressure

OBJECTIVE

The new direct gradual cranial expansion surgical technique has been used to treat children with postshunt microcephaly and slit ventricle syndrome. To evaluate the feasibility of this new surgical treatment, we studied intracranial pressure (ICP) in microcephalic children with developmental delay.

METHODS

Mean ICP, age, sex, head size, and developmental assessments were compared in 24 microcephalic children with developmental delay who had had continuous ICP monitoring.

RESULTS

Children studied included 9 boys and 15 girls with a mean age of 4.9 ± 2.0 years. Mean ICP was 18.7 ± 8.6 mm Hg. Children with high ICP had significantly lower age and higher B wave ratios than children with low ICP. There were no statistically significant differences in developmental scores and head sizes between children with high ICP and children with low ICP. In multiple linear regression analysis, we observed significantly increased risk of mean ICP elevation by B wave ratio and developmental score and decreased risk of mean ICP elevation by age, but not significantly increased risk of mean ICP elevation by head circumferences (z score).

CONCLUSIONS

Our findings suggest that a portion of microcephalic children with developmental delay have high ICP that cannot be expected from head sizes, and high ICP has decreasing tendency with age.

Nervous System Injury and Neuroimaging of Zika Virus Infection

In 2016, World Health Organization announced Zika virus infection and its neurological sequalae are a public health emergency of global scope. Preliminary studies have confirmed a relationship between Zika virus infection and certain neurological disorders, including microcephaly and Guillain–Barre syndrome (GBS). The neuroimaging features of microcephaly secondary to Zika virus infection include calcifications at the junction of gray–white matter and subcortical white matter with associated cortical abnormalities, diminution of white matter, large ventricles with or without hydrocephalus, cortical malformations, hypoplasia of cerebellum and brainstem, and enlargement of cerebellomedullary cistern. Contrast enhancement of the cauda equine nerve roots is the typical neuroimaging finding of GBS associated with Zika virus. This review describes the nervous system disorders and associated imaging findings seen in Zika virus infection, with the aim to improve the understanding of this disease. Imaging plays a key role on accurate diagnosis and prognostic evaluation of this disease.

Zika Virus Infection in Pregnant Women in Rio de Janeiro

BACKGROUND

Zika virus (ZIKV) has been linked to central nervous system malformations in fetuses. To characterize the spectrum of ZIKV disease in pregnant women and infants, we followed patients in Rio de Janeiro to describe clinical manifestations in mothers and repercussions of acute ZIKV infection in infants.

METHODS

We enrolled pregnant women in whom a rash had developed within the previous 5 days and tested blood and urine specimens for ZIKV by reverse-transcriptase-polymerase-chain-reaction assays. We followed women prospectively to obtain data on pregnancy and infant outcomes.

RESULTS

A total of 345 women were enrolled from September 2015 through May 2016; of these, 182 women (53%) tested positive for ZIKV in blood, urine, or both. The timing of acute ZIKV infection ranged from 6 to 39 weeks of gestation. Predominant maternal clinical features included a pruritic descending macular or maculopapular rash, arthralgias, conjunctival injection, and headache; 27% had fever (short-term and low-grade). By July 2016, a total of 134 ZIKV-affected pregnancies and 73 ZIKV-unaffected pregnancies had reached completion, with outcomes known for 125 ZIKV-affected and 61 ZIKV-unaffected pregnancies. Infection with chikungunya virus was identified in 42% of women without ZIKV infection versus 3% of women with ZIKV infection (P<0.001). Rates of fetal death were 7% in both groups; overall adverse outcomes were 46% among offspring of ZIKV-positive women versus 11.5% among offspring of ZIKV-negative women (P<0.001). Among 117 live infants born to 116 ZIKV-positive women, 42% were found to have grossly abnormal clinical or brain imaging findings or both, including 4 infants with microcephaly. Adverse outcomes were noted regardless of the trimester during which the women were infected with ZIKV (55% of pregnancies had adverse outcomes after maternal infection in the first trimester, 52% after infection in the second trimester, and 29% after infection in the third trimester).

CONCLUSIONS

Despite mild clinical symptoms in the mother, ZIKV infection during pregnancy is deleterious to the fetus and is associated with fetal death, fetal growth restriction, and a spectrum of central nervous system abnormalities. (Funded by Ministério da Saúde do Brasil and others.).

Congenital cerebral malformations and dysfunction in fetuses and newborns following the 2013 to 2014 Zika virus epidemic in French Polynesia

We detected an unusual increase in congenital cerebral malformations and dysfunction in fetuses and newborns in French Polynesia, following an epidemic of Zika virus (ZIKV), from October 2013 to March 2014. A retrospective review identified 19 cases, including eight with major brain lesions and severe microcephaly, six with severe cerebral lesions without microcephaly and five with brainstem dysfunction without visible malformations. Imaging revealed profound neurological lesions (septal and callosal disruption, ventriculomegaly, abnormal neuronal migration, cerebellar hypoplasia, occipital pseudocysts, brain calcifications). Amniotic fluid was drawn from seven cases at gestation weeks 20 to 29. ZIKV RNA was detected by RT-PCR and infectious ZIKV isolates were obtained in four of five microcephalic, but not in two non-microcephalic cases with severe brain lesions. Medical termination of pregnancy was performed in eleven cases; two cases with brainstem dysfunction died in the first months of life; six cases are alive, with severe neurological impairment. The results show that four of seven tested fetuses with major neurological injuries were infected with ZIKV in utero. For other non-microcephalic, congenital abnormalities we were not able to prove or exclude ZIKV infection retrospectively. The unusual occurrence of brain malformations or dysfunction without microcephaly following a ZIKV outbreak needs further studies.

Association between Zika virus and microcephaly in French Polynesia, 2013-15: a retrospective study

BACKGROUND

The emergence of Zika virus in the Americas has coincided with increased reports of babies born with microcephaly. On Feb 1, 2016, WHO declared the suspected link between Zika virus and microcephaly to be a Public Health Emergency of International Concern. This association, however, has not been precisely quantified.

METHODS

We retrospectively analysed data from a Zika virus outbreak in French Polynesia, which was the largest documented outbreak before that in the Americas. We used serological and surveillance data to estimate the probability of infection with Zika virus for each week of the epidemic and searched medical records to identify all cases of microcephaly from September, 2013, to July, 2015. Simple models were used to assess periods of risk in pregnancy when Zika virus might increase the risk of microcephaly and estimate the associated risk.

FINDINGS

The Zika virus outbreak began in October, 2013, and ended in April, 2014, and 66% (95% CI 62-70) of the general population were infected. Of the eight microcephaly cases identified during the 23-month study period, seven (88%) occurred in the 4-month period March 1 to July 10, 2014. The timing of these cases was best explained by a period of risk in the first trimester of pregnancy. In this model, the baseline prevalence of microcephaly was two cases (95% CI 0-8) per 10,000 neonates, and the risk of microcephaly associated with Zika virus infection was 95 cases (34-191) per 10,000 women infected in the first trimester. We could not rule out an increased risk of microcephaly from infection in other trimesters, but models that excluded the first trimester were not supported by the data.

INTERPRETATION

Our findings provide a quantitative estimate of the risk of microcephaly in fetuses and neonates whose mothers are infected with Zika virus.

FUNDING

Labex-IBEID, NIH-MIDAS, AXA Research fund, EU-PREDEMICS.

Congenital microcephaly with a simplified gyral pattern: associated findings and their significance

BACKGROUND AND PURPOSE

Primary microcephaly is an incompletely understood malformation that is often associated with developmental brain anomalies, yet whether the associated anomalies result from the microcephaly itself or from associated developmental/genetic mishaps is not yet understood. This study reviewed and analyzed a large number of MR imaging scans of children with microcephaly to determine the frequency of associated morphologic findings and to assess whether these findings were associated with the severity of the microcephaly.

MATERIALS AND METHODS

MR images of 119 patients with clinically diagnosed microcephaly were retrospectively reviewed, focusing on the degree of microcephaly, simplification of gyri, white matter volume, abnormalities of the corpus callosum, size and structure of posterior fossa contents, and myelination. Associations among the findings were evaluated by using the Spearman correlation coefficient and the Fisher exact test.

RESULTS

Among 7 patients with mild, 42 with moderate, and 70 with extreme microcephaly, a significant correlation was identified between a greater degree of microcephaly and both a greater degree of simplified gyration and decreased white matter volume. The severity of the callosal anomaly showed a lower but still significant correlation with the severity of microcephaly. Degree of hypoplasia of posterior fossa structures, delay in myelination, and abnormality of the basal ganglia did not correlate with the degree of microcephaly.

CONCLUSIONS

A strong correlation was found between the degree of microcephaly, the volume of white matter, and the presence of a simplified gyral pattern. These associations should be considered when attempting to use neuroimaging for segregation and classification of patients with microcephaly.