Necessity of Intracranial Imaging in Infants and Children With Macrocephaly

Epidemiology of Macrocephaly in the Texas Birth Defects Registry, 1999-2019

BACKGROUND

Macrocephaly is a clinical observation denoted as an occipitofrontal head circumference exceeding two standard deviations above same age and sex norms. By its definition, macrocephaly occurs in approximately 3% of the population. Descriptive epidemiologic evaluations of macrocephaly are lacking in the literature. The primary objective of this study was to describe the prevalence of macrocephaly captured by the Texas Birth Defects Registry (TBDR) by infant sex, rural/urban residence, and select maternal characteristics.

METHODS

Cases of TBDR between 1999 and 2019 with a six-digit Centers for Disease Control modified-British Pediatric Association (BPA) code of 742.400 (enlarged brain/head, large head, macrocephaly, megalencephaly) were identified. All pregnancy outcomes and diagnostic certainties were included. Prevalence (per 10,000 live births) and 95% confidence intervals (CIs) were calculated using a Poisson table by rural/urban residence, infant sex, maternal age, education, race/ethnicity, history of diabetes, and body mass index (BMI). Prevalence calculations were repeated across multiple sensitivity analyses including (1) definite, isolated cases excluding those with indication of being either "benign" or "familial", (2) definite, non-isolated cases, (3) definite non-isolated cases excluding chromosomal and syndromic cases, and (4) definite, proportionate (at birth) cases. A secondary objective was to describe the most common co-occurring congenital defects among definite, non-isolated cases.

RESULTS

Overall, between 1999 and 2019, 14,637 cases of macrocephaly were identified in the TBDR resulting in a prevalence of 18.12/10,000 live births (95% CI: 17.83-18.42). Most cases were live born (99%), had a definite diagnosis (87%), and were non-isolated (57%). Prevalence was significantly higher among males, among those with an urban residence, and among mothers who were older, Non-Hispanic White, who had greater than high school education, who had a history of diabetes, and who were obese. Prevalence patterns remained consistent across all sensitivity analyses. The most common co-occurring congenital defects among definite, non-isolated cases were minor and primarily included skull and facial bone anomalies (e.g., plagiocephaly [18%]).

CONCLUSIONS

To our knowledge, this is the first epidemiologic evaluation of macrocephaly in a birth defects registry. The long-term clinical impact of isolated macrocephaly is not well understood and should be the focus of future investigations.

Diagnostic Pitfalls of Macrocephaly and Intracranial Dural Arteriovenous Fistulas: Connecting the Dots With the Red Flags

Macrocephaly is defined as an abnormal increase in head circumference greater than two standard deviations above the mean for a given age and sex. We present the case of a 16-month-old boy with congenital progressive macrocephaly, who was referred to our hospital for a ventriculoperitoneal shunt placement for external hydrocephalus diagnosed at 13 months of age. The patient had a febrile seizure 12 hours after the shunt was placed and the emergency CT exam revealed collapsed ventricles and a right frontal subdural collection, suggestive of an over-drainage and intracranial hypotension. A subsequent electroencephalogram (EEG) revealed some anomalies, but the patient was discharged two days later due to having no neurological symptoms after being placed on anticonvulsants. The patient returned to the hospital one week later due to recurrent seizures. Further clinical examination revealed prominent and tortuous veins of the skull, palpated in the left occipital region. A thrill and a left carotid murmur were heard during auscultation. A subsequent brain MRI with MR arteriography and venography was performed in search of an explanation for hydrocephaly. The sequences were suggestive of a dural arteriovenous fistula, which was confirmed and then treated using coils during an interventional angiography. A second procedure was performed two months later to complete the embolization, with subsequent imaging follow-ups showing the procedure to have been successful. The measurement of the cranial circumference, its regular evaluation, and its evolution allow a hierarchical diagnosis strategy by distinguishing primary and secondary macrocephaly, progressive or not. Dural arteriovenous fistulas (DAVF) are an under-appreciated cause of macrocephaly, with which they are associated in 35% of cases. Intracranial DAVFs are pathologic shunts between dural arteries and dural venous sinuses, meningeal veins, or cortical veins. Patients with DAVFs may be completely asymptomatic. Symptoms, when present, may range from neurological deficits, seizures, and hydrocephaly to fatal hemorrhage. The symptoms depend on the location and venous and drainage patterns of the DAVF. They can be difficult to identify on routine MRIs unless specifically searched for, especially in cases of technically suboptimal examinations. We aim to give a practical approach to identify the clinical clues that warrant further investigation. Several specific protocols exist regarding the management of macrocephaly and should be followed carefully once a diagnosis has been reached, but further studies are needed to integrate more clinical and neuroimaging findings to permit an early diagnosis.

Clinical factors associated with need for neurosurgical care in young children with imaging for macrocephaly: a case control study

BACKGROUND

Macrocephaly is present in 2.3% of children with important neurosurgical conditions in the differential diagnosis. The objective of this study was to identify clinical associations with actionable imaging findings among children with head imaging for macrocephaly.

METHODS

We conducted a case-control study of head imaging studies ordered for macrocephaly among children 24 months and younger in a multistate children's health system. Four neurosurgeons reviewed the images, determining cases to be a 'concern' if neurosurgical follow-up or intervention was indicated. Electronic health records were reviewed to collect patient-level data and to determine if surgery was performed. Controls were matched 3:1 to cases of 'concern' in a multivariate model using conditional logistic regression.

RESULTS

In the study sample (n = 1293), 46 (4%) were concern cases, with 15 (1%) requiring surgery. Significant clinical factors associated with neurosurgical concern were bulging fontanel [aOR 7.47, (95% CI: 2.28-24.44), P < 0.001], prematurity [aOR 21.26, (95% CI: 3.76-120.21), P < 0.001], any delay [aOR 2.67, (95% CI: 1.13-6.27), P = 0.03], and head-weight Z-score difference (W_diff, defined as the difference between the Z-scores of head circumference and weight) [aOR 1.70, (95% CI: 1.22-2.37), P = 0.002].

CONCLUSIONS

Head imaging for macrocephaly identified few patients with findings of concern and fewer requiring surgery. A greater head-weight Z-score difference appears to represent a novel risk factor for neurosurgical follow-up or intervention.

Imaging of Macrocephaly

Macrocephaly is a common diagnosis in the pediatric population, particularly in the infantile time period. There is a wide range of causes of macrocephaly, from benign to malignant, for which imaging plays a key role in the diagnosis and clinical guidance. Our aim is to review the distinct and prevalent neuroimaging findings in the evaluation of the macrocephalic infant.

Imaging in the study of macrocephaly: Why?, when?, how?

Macrocephaly is a clinical term defined as an occipitofrontal circumference more than two standard deviations above the mean. It is present in 5% of children and is a common indication for imaging studies. There are multiple causes of macrocephaly; most of them are benign. Nevertheless, in some cases, macrocephaly is the clinical manifestation of a condition that requires timely medical and/or surgical treatment. The importance of imaging studies lies in identifying the patients who would benefit from treatment. Children with macrocephaly associated with neurologic alterations, neurocutaneous stigmata, delayed development, or rapid increase of the circumference have a greater risk of having disease. By contrast, parental macrocephaly is predictive of a benign condition. Limiting imaging studies to patients with increased risk makes it possible to optimize resources and reduce unnecessary exposure to tests.

Macrocephaly in the Primary Care Provider's Office

Macrocephaly is commonly encountered in the primary care provider's office. It is defined as an occipitofrontal circumference that is greater than 2 standard deviations above the mean for the child's given age. Macrocephaly is a nonspecific clinical finding that may be benign or require further evaluation. An algorithmic approach is useful for aiding in the clinical decision-making process to determine if further evaluation with neuroimaging is warranted. Abnormal findings may signify a harmful underlying cause, requiring referral to a genetic specialist or neurosurgeon.

Asymptomatic macrocephaly: to scan or not to scan

BACKGROUND

Macrocephaly is a common finding in infants and is often idiopathic or familial. In the absence of clinical signs and symptoms, it can be difficult to determine when concern for underlying pathology is justified.

OBJECTIVES

The objectives of this study were to determine the utility of screening head ultrasound (US) in asymptomatic infants with macrocephaly and to identify clinical factors associated with significant US findings.

MATERIALS AND METHODS

A 20-year retrospective review was performed of infants undergoing head US for macrocephaly or rapidly increasing head circumference. Data collected included age, gender, head circumference at birth and at the time of US, specialty of the ordering physician, US findings, computed tomography (CT) or magnetic resonance imaging (MRI) findings, and clinical course including interventions.

RESULTS

Four hundred and forty infants met inclusion criteria. Two hundred and eighty studies (64%) were found to be normal, 137 (31%) had incidental findings, 17 (3.8%) had indeterminate but potentially significant findings, and 6 (1.4%) had significant findings. Twenty of the 23 infants with indeterminate or significant findings had subsequent CT or MRI. This confirmed significant findings in eight infants (1.8%): three subdural hematomas, two intracranial tumors, two aqueductal stenoses, and one middle fossa cyst. Five of the eight infants required surgical procedures. The only statistically significant association found with having a significant finding on head US was head circumference at birth.

CONCLUSION

Ultrasound is a useful initial study to evaluate infantile macrocephaly, identifying several treatable causes in our study and, when negative, effectively excluding significant pathology.

Diagnostic Approach to Macrocephaly in Children

Macrocephaly affects up to 5% of the pediatric population and is defined as an abnormally large head with an occipitofrontal circumference (OFC) >2 standard deviations (SD) above the mean for a given age and sex. Taking into account that about 2-3% of the healthy population has an OFC between 2 and 3 SD, macrocephaly is considered as "clinically relevant" when OFC is above 3 SD. This implies the urgent need for a diagnostic workflow to use in the clinical setting to dissect the several causes of increased OFC, from the benign form of familial macrocephaly and the Benign enlargement of subarachnoid spaces (BESS) to many pathological conditions, including genetic disorders. Moreover, macrocephaly should be differentiated by megalencephaly (MEG), which refers exclusively to brain overgrowth, exceeding twice the SD (3SD-"clinically relevant" megalencephaly). While macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, megalencephaly is most likely due to a genetic cause. Apart from the head size evaluation, a detailed family and personal history, neuroimaging, and a careful clinical evaluation are crucial to reach the correct diagnosis. In this review, we seek to underline the clinical aspects of macrocephaly and megalencephaly, emphasizing the main differential diagnosis with a major focus on common genetic disorders. We thus provide a clinico-radiological algorithm to guide pediatricians in the assessment of children with macrocephaly.

Medulloblastoma, macrocephaly, and a pathogenic germline PTEN variant: Cause or coincidence?

Background

Medulloblastomas (MBs) are a heterogeneous group of childhood brain tumors with four consensus subgroups, namely MB_SHH, MB_WNT, MB_{Group 3}, and MB_{Group 4}, representing the second most common type of pediatric brain cancer after high‐grade gliomas. They suffer from a high prevalence of genetic predisposition with up to 20% of MB_SHH caused by germline mutations in only six genes. However, the spectrum of germline mutations in MB_SHH remains incomplete.

Methods

Comprehensive Next‐Generation Sequencing panels of both tumor and patient blood samples were performed as molecular genetic characterization. The panels cover genes that are known to predispose to cancer.

Results

Here, we report on a patient with a pathogenic germline PTEN variant resulting in an early stop codon p.(Glu7Argfs*4) (ClinVar ID: 480383). The patient developed macrocephaly and MB_SHH, but reached remission with current treatment protocols.

Conclusions

We propose that pathogenic PTEN variants may predispose to medulloblastoma, and show that remission was reached with current treatment protocols. The PTEN gene should be included in the genetic testing provided to patients who develop medulloblastoma at an early age. We recommend brain magnetic resonance imaging upon an unexpected acceleration of growth of head circumference for pediatric patients harboring pathogenic germline PTEN variants.