Guidelines for Measuring Head Circumference in Children and the Management of Macrocephaly
|Publication: 13/09/2021 --|
|Last review: 01/01/1900|
|Next review: 13/09/2024|
|Approved By: Trust Clinical Guidelines Group|
|Copyright© Leeds Teaching Hospitals NHS Trust 2021|
This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
Guidelines for Measuring Head Circumference in Children and the Management of Macrocephaly
Table adapted from A. Seal Fifteen minute consultation on the infant with a large head.
Macrocephaly is defined as a head circumference (specifically an occipitofrontal circumference [OFC]) greater than 2 standard deviations above the mean for a given age and sex, which falls above the 97th centile. It includes increased head circumference due to all intracranial and cranial structures, including those caused by scalp, skull, subdural space, hydrocephalus and intracranial masses, as well as the brain itself.
I.e. Macrocephaly = large head size.
Megalencephaly also presents with head circumference above 2 standard deviations for the age and gender-related mean, but refers to the overgrowth of cerebral structures themselves. i.e megalencephaly = large brain size.
Both may involve either a normally or abnormally functioning brain. By definition, macrocephaly is not uncommon and represents a clinical finding rather than a diagnosis. Indeed, it can be isolated and benign or represents the first sign of an underlying congenital, genetic or acquired condition. As such, it is critical clinicians understand macrocephaly and its various aetiologies in order to help distinguish between those individuals with a head size simply at the upper end of the population curve and those which may require further investigation and management.
It is also important to note that although macrocephaly or megalencephaly will not fit the clinical definition until the head circumference has crossed the 97th centile, a child whose head circumference is crossing upwards on the centiles should prompt investigation of the same potential underlying pathological causes e.g. a child who has been growing along the 2nd-9th centile for weight, but with a head circumference increasing from the 9th to the 50th centile, should still be investigated as the head circumference is increasing disproportionately to body weight, despite the measurements being well within the ‘normal’ range. As with most measurements/observations, the trend of the head circumference measurement is far more useful than a ‘one-off’ measurement.
The human skull contains three components: cerebrospinal fluid (CSF), blood and brain. In adults, the Monro-Kellie doctrine states the volume of the cranium is fixed and thus an increase in volume of any of the above must result in a reciprocal decrease in the volume of the other two components to maintain equilibrium. However, prior to the closure of the fontanelles in children this does not apply and an increase in any of these components will cause the head to expand.
Adapted from Fenichel's Clinical Pediatric Neurology: A Signs and Symptoms Approach, 7th edition, 2013.
I. Hydrocephalus (↑CSF)
- Aqueductal stenosis*
- Chiari malformation*
- Dandy-Walker malformation*
- Klippel-Feil syndrome
- Mass lesions*
- Tumours and neurocutaneous disorders
- Vein of Galen malformation*
- Walker-Warburg syndrome
- Basilar impression
- Choroid plexus papilloma*
- Meningeal malignancy
- Meningitis*, **
- Benign enlargement of subarachnoid space
II. Megalencephaly (↑brain parenchyma)
Anatomical – typically macrocephalic at birth but with normal intracranial pressure (ICP)
- Benign or familial
- Cerebral gigantism (Sotos syndrome)
- Fragile X syndrome*
- Neurocutaneous disorders
- Epidermal nevus syndrome, Hypomelanosis of Ito, Incontinentia pigmenti, Neurofibromatosis, Tuberous sclerosis
Metabolic – typically normocephalic at birth with megalencephaly resulting later due to cerebral oedema
- Alexander disease
- Canavan disease
- Globoid leukodystrophy
- Megalencephalic leukoencephalopathy with subcortical cysts
- Metachromatic leukodystrophy
- Glutaric aciduria type I**
- Maple syrup urine disease**
III. Thickened skull
- Cleidocranial dysostosis
- Craniometaphyseal dysplasia of Pyle
- Epiphyseal dysplasia
- Leontiasis ossea
- Orodigitofacial dysostosis
- Osteogenesis imperfecta
- Russell-Silver dwarfism
(*Denotes the most common conditions, ** the ones with disease modifying treatments. In cases of hydrocephalus, neurosurgical intervention such as ventriculoperitoneal shunt may be indicated, and treatment of the underlying cause will depend upon the particular aetiology.)
As always in Paediatrics, consider non-accidental injury as a potential underlying cause of unexplained macrocephaly. Chronic subdural haematomas can lead to a chronic enlarged subdural space or intracranial haematomas can cause post-haemorrhagic hydrocephalus. If there are concerns, discuss with a senior colleague or the consultant on call for safeguarding.
Occipitofrontal circumference (OFC), measured from the most prominent part of the glabella to the most prominent posterior area of the occiput, is an essential part of the paediatric examination. It is ideally performed using a disposable paper tape measure with three measurements taken and the largest value recorded, being mindful of factors which may affect its accuracy (such as thick hair, cephalhaematoma etc.).
The WHO advises it be measured regularly; around birth (though measurements taken within the first 24 hours can be unreliable due to moulding), at the 8 week check, and any time thereafter if there are concerns about the child’s head growth, weight gain, growth, development or general health. More generally, OFC should be also measured at extremes of body weight (either below 0.4th centile or above 99.6th centile) or if there is very rapid weight gain.
Head size measurements are most informative when plotted over time; though variation can occur, most recordings track within one centile space and under 1% of infants either rise or fall by more than two centiles after the first few weeks of life. As such, rapid growth or slowing of growth requires urgent attention, with the former in particular suggestive of hydrocephalus.
3.2 When to measure head circumference in children
3.2.1 All children under 2 years of age, being seen in any paediatric clinic in the outpatient department, should have their head circumference measured and plotted on a growth chart.
3.2.2. In children presenting acutely to A&E, CAT unit or any in-patient ward/assessment area, given the busy nature of these areas, a targeted head circumference measurement is more practical. In these areas the head circumference should be measured if a child presents with any of the following concerns/presentations, particularly if younger than 2 years of age:
- Persistent vomiting
- Developmental delay/developmental regression
- Concerns about lethargy (unexplained by an acute illness)
- Failure to thrive
- Behavioural change
- Parental concern about head size or shape
- Non-accidental injury
- Headaches in young children
- Unexplained irritability
- Potential ventriculoperitoneal shunt dysfunction (i.e. children with VP shunts presenting with headache/temperature/vomiting/other signs of raised ICP)
The assessment of macrocephaly requires taking a detailed history from both the child and parents, alongside a comprehensive examination.
Key questions include:
- Antenatal history
- Birth weight, length, OFC (i.e. to determine age of onset)
- Birth history – screening for risk factors/causes associated with hydrocephalus (including meningitis, intra-ventricular haemorrhage)
- Significant events of ill health
- Developmental history, including the loss of previously required skills (i.e. regression)
- Family history of malignancy or any genetic, neurological, metabolic and developmental conditions
- History of large head in family members
- Red flags suggestive of raised ICP
- Developmental delay
- Behavioural changes
Key aspects of examination include:
- Careful plotting of OFC, weight and height values on age and gender appropriate chart with comparison to previous recordings
- Blood pressure must be documented
- Red flags suggestive of raised ICP
- Bulging fontanelle
- Distended scalp veins
- Visible sclera above iris of eye (sun-setting sign)
- Abnormal neurological signs
- Abnormalities in muscle tone (e.g. hypotonia, spasticity) and posture
- Persistence of primitive reflexes
- Sixth cranial nerve palsy
- Dysmorphic features, suggestive of a particular syndrome
- Skin abnormalities (e.g. café-au-lait spots, axillary freckling, ash-leaf spots)
- Eye abnormalities (e.g. papilloedema, cataract, retinal abnormalities)
- Developmental assessment, for example examining for cognitive impairment, behavioural difficulties or autistic features
- MSK examination (e.g. skeletal dysplasia)
- Abdomen (e.g. hepatosplenomegaly, as seen in metabolic storage disorders)
- Parental OFC
Management of situations where there is need for urgent neuroimaging:
Once the presence of macrocephaly has been correctly established, the first and most important step is to assess for: i) the presence of signs and symptoms suggestive of hydrocephalus or raised ICP; or ii) whether OFC is climbing centiles. If either is true, the clinician should arrange emergency transfer to the Paediatric Emergency or Intensive Care teams for assessment and urgent neuroimaging. Here, MRI is generally preferable but depends on a range of variables including suspected aetiology.
Out of hours, or if MRI is not immediately available, if there are concerns of raised ICP/focal neurological deficit/other urgent concerns regarding aetiology or symptoms, CT head should be considered. In children <1 year of age with open fontanelles, cranial ultrasound is a relatively quick and accessible method of neuroimaging, but is less sensitive than CT, and it is likely that CT/MRI will be necessary anyway. Discuss with the radiologist on call/paediatric consultant on call regarding suitable imaging modality and timing.
Management of situations where there are no immediate concerns that warrant urgent neuroimaging:
If there are no indicators of raised intracranial pressure or acutely enlarging head circumference across centiles, the clinician should then assess for specific features suggestive of an underlying cause, including any syndromic features. If so, directed testing should take place, such as molecular genetic testing in the case of Fragile X syndrome, or urine metabolic screening for mucopolysaccharidoses, for example.
If no specific diagnosis is immediately apparent but there is evidence of developmental delay, again MRI should be the next step. Subsequent investigations are guided by the MRI findings, but if normal the clinician should again consider liaising with the Paediatric Metabolic team for testing for the presence of storage disorders.
Finally, if none of the above are applicable (i.e. there are no concerns for hydrocephalus or raised ICP, abnormal neurological signs, syndromic features or developmental delay), one should consider skull/scalp causes or, as a diagnosis of exclusion, benign/familial macrocephaly (FM), providing all three of DeMyer’s criteria are met:
- Absence of evidence of a syndrome
- Normal radiographic study of the brain
- A parent or sibling with macrocephaly, or macrocephaly that can be traced through several generations
In such cases, once the diagnosis of FM has been confirmed, strong safety-netting should be provided to parents/carers with advice to monitor closely for the development of any neurological and developmental concerns.
4. 2 Haematology/biochemistry:
- FBC – to rule out anaemia, haemoglobinopathies, lymphoproliferative disorders
- Bone profile, Vitamin D and PTH
- Blood/urine organic and amino acids
- Blood acylcarnitines
4. 3 Genetics:
- Many of the conditions listed above have had specific genes identified in the vast majority of cases
- Consider CGH array if developmental delay but no syndromic features/no MRI findings
More generally, management and prognosis will depend on the underlying cause; ranging from urgent neurosurgical intervention in children with hydrocephalus to simple safety-netting, reassurance and careful monitoring in those with FM.
5.1 Inpatient management:
If the child is unwell, or there is any suspicion of raised ICP, the child should be assessed in an urgent A-E approach, with discussion with radiology/neurosurgery/neurology as appropriate. Children with ventriculoperitoneal shunts in situ should be managed as per the VP shunt guideline.
Dependent on the presentation, suspected aetiology, or radiological findings, discussion with and input from neurosurgery, neurology, metabolic, ophthalmology, genetics, endocrine and community paediatric teams may be necessary.
5.2 Outpatient management:
If the child presents to the outpatient department and the child is well with no concerning features of raised ICP/abnormal neurology or developmental concerns requiring inpatient assessment and management, it may be that the child can be managed in the outpatient department/community paediatrics or that they can be discharged to primary care to be monitored. If the child presents acutely but can be discharged, it may be that the head circumference requires surveillance in the community, in which case a clear plan for the measurement of the OFC, including the expected action of the GP/health visitor asked to take measurements, should be clearly documented in the discharge letter, along with safety netting advice for parents.
During the initial stages of investigation and management it may be difficult to prognosticate, which can be worrying for parents, especially if there are concerns regarding abnormal movements/seizures, developmental delay/regression or the child has been unwell. Depending on the cause of macrocephaly, timely intervention can improve outcomes, demonstrating the importance of regular head circumference measurement in young children, and acknowledging concerns from parents.
To ensure the correct methods used to measure head circumference, or also known as occipito-frontal circumference (OFC), in children and identify and appropriately investigate/manage children with enlarged head circumference.
|Target patient group:||Children aged 0-5 years|
|Target professional group(s):||Secondary Care Doctors
Secondary Care Nurses
Eric Piña-Garza J. Fenichel's Clinical Pediatric Neurology: A Signs and Symptoms Approach. 7th ed. Philadelphia, PA: Elsevier; 2013. Chapter 18, Disorders of cranial volume and shape; p. 348-365.
Royal College of Paediatrics and Child Health. Macrocephaly. Last updated 2018. Available at: https://childprotection.rcpch.ac.uk/wp-content/uploads/sites/6/2020/04/Macrocephaly-aap.ppcqr_.396094.70.20190125.105843.2.pdf
Seal A. Fifteen-minute consultation on the infant with a large head. Archives of Disease in Childhood - Education and Practice. 2013; 98:122-125.
Royal College of Paediatrics and Child Health. Measuring and Plotting: UK-WHO Growth Charts - Fact Sheet 3. 2009. Available at: https://www.rcpch.ac.uk/sites/default/files/Measuring_and_plotting_advice.pdf
Royal College of Paediatrics and Child Health. Plotting and assessing infants and toddlers up to age 4 years: UK-WHO Growth Charts - Fact Sheet 6. 2009. Available at: https://www.rcpch.ac.uk/sites/default/files/Plotting_toddlers.pdf
DeMyer W. Megalencephaly: Types, Clinical syndromes, and Management. Pediatric Neurol 1986; 2:321–328.
NICE. Quality statement 2: Head size and shape in children. Suspected neurological conditions: recognition and referral. Last updated 2021. Available at: https://www.nice.org.uk/guidance/qs198/chapter/Quality-statement-2-Head-size-and-shape-in-children
Trust Clinical Guidelines Group
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