Introduction

Macrocephaly is probably not a common condition that the ordinary person would have heard of; however, it is a condition that affects children all across the globe. An infant is diagnosed with macrocephaly when their head circumference is 2 standard deviations above the given value for their gender and age.¹ This condition can be benign or caused by other pathological underlying issues. 

A main component of the management of this condition is longitudinal monitoring of the head growth of affected children. In this article, we will explore the importance of this continuous monitoring and how it can guide treatment plans. 

Epidemiology and Aetiology of Macrocephaly

Macrocephaly affects approximately 1 in every 1,000 babies, with a higher prevalence in females.² Although this accounts for about 2% of births, most infants will be normal with no underlying health issues.³

In order to effectively treat and manage an infant with macrocephaly, it is important to identify the cause. There are several causes; however, the most common are: 

• Increased brain tissue- this type of macrocephaly is commonly known as megalencephaly
• Genetic conditions- Sotos syndrome is a rare condition passed down from parents that features macrocephaly as one of the main symptoms
• Hydrocephalus- this occurs when there is an increase in the cerebrospinal fluid and can cause an increase in an infant's head circumference⁴

Normal Head Growth Patterns in Children

Before we can dive into monitoring head circumference figures in children with macrocephaly, we need to understand what normal head growth patterns look like. 

Firstly, head circumference is the measurement of a baby's head around its largest circumference. This is measured regularly at routine pediatric appointments in a child's first few years of life. This can be a good indicator of normal physiological development.

At birth, the average head circumference is 35cm, which increases by 1cm on average each month in the first year of life. From 12 months to 36 months, the increase of the head circumference will dramatically slow down, with only an increase of 3.5cm in two years.⁵ 

Longitudinal Monitoring Approach

Measurement technique

In order to get an accurate value of an infant's head circumference, the proper technique and tools should be used. This measurement must be taken with a tool that is flexible and long enough to wrap around the child's head, like a measuring tape. Next, this tape should be wrapped tightly around the head(however, not too tightly as this might be uncomfortable), from the protruding part of the forehead to the widest part of the back of the head. This can be repeated two to three times, and the largest number from this can be used as the final value.⁶

Documentation

Once the head circumference has been determined, it is important to record this information accurately for future reference. This figure is usually plotted on a standardised growth chart each time it is taken. This makes it easy for healthcare professionals to see if there are any anomalies. However, it is important to remember that these charts are interpreted in conjunction with other factors like age, gender and whether or not a child was born prematurely. 

Clinical Assessment and Diagnostic Workup

Alongside head circumference measurements, other assessments and diagnostic tests can be carried out. 

History taking

It is important to get a complete medical history of the infant from their parents or guardians. Inquiring about developmental milestones such as walking, talking, and social interactions can help determine if further tests are required. Additionally, some infants may present with larger head circumferences; however, adequate data gathering might reveal a pattern of large heads in an infant's family. 

Physical exam

Although head circumference measurement is a type of physical examination, there are additional physical examinations that can be carried out if there are suspicions of macrocephaly. Examining an infant's fontanelles can reveal things like bulging, which could be a cause of increased head circumference and a sign of a more serious condition. 

Imaging

In addition to head circumference measurements, healthcare professionals might suggest doing additional tests like MRI and CT scans. This can help visualise the brain and the bones of the skull. 

Clinical Significance of Longitudinal Monitoring

Longitudinal monitoring of head circumference through routine measurements is crucial. It can help in differentiating between benign and pathological conditions. If longitudinal monitoring reveals a large head circumference without any symptoms or findings on additional tests, this can be used to reassure concerned parents and guardians. Additionally, this can assist in the early detection of certain conditions like hydrocephalus or cerebral oedema. Once these conditions are detected, it can aid in timely and life-saving treatment. 

Management and Follow-up

Due to the varied causes of macrocephaly, there are several ways to manage this condition based on the cause. In cases of benign causes like benign familial macrocephaly, no treatment is required; however, regular monitoring might be needed to monitor the condition. In children whose macrocephaly is caused by conditions like hydrocephalus, neurosurgical treatment is required. Surgeons may need to do procedures to drain some of the fluid in the brain, which will help relieve some of the symptoms, like increased intracranial pressure.⁷

Regardless of the cause, the management and follow-up of macrocephaly requires multidisciplinary care, which includes a wide range of doctors such as paediatricians, surgeons, and other healthcare professionals like nurses. 

Challenges and Considerations

With every condition, there are challenges that arise. As we've gathered, longitudinal monitoring is crucial; however, in areas of the world where resources are limited, it can be difficult for families to have access to healthcare professionals with the skills and tools to not only measure head circumference but also accurately diagnose macrocephaly.

Another issue that might arise is the discrepancies in the ranges of normal head circumferences across healthcare institutions. One value might be considered normal in one hospital but abnormal in another. This could result in either a delay of life-saving treatment or result in an infant undergoing unnecessary tests and treatment. This is why it is important for healthcare professionals to use standardised growth charts that take into account factors such as age and gender. 

Summary 

Macrocephaly is a condition that is characterised by a large head circumference in infants. This condition affects 1 in 1000 infants and can be caused by a variety of factors. The causes of this condition can either be benign or pathological, and they include hydrocephalus, cerebral oedema, genetic conditions and increased brain tissue. Head circumference is measured regularly during the first few years of a child's life and is usually plotted on a growth chart to monitor for any abnormal changes. This measurement is taken by wrapping a measuring tape around a child's head from the most prominent part of their forehead to the widest part of the back of the head. 

If this measurement raises any suspicions in healthcare professionals, additional tests such as physical examinations and CT and MRI scans can be conducted to come to a diagnosis. Depending on the cause of the macrocephaly, treatments such as surgery or regular follow-up visits will be recommended. However, due to limited resources in certain areas of the world and discrepancies between institutions, treatment is sometimes delayed.