What Is Macrocephaly?

When an infant's head circumference exceeds 2 standard deviations away from the average, known as the 97th percentile, the infant is said to have macrocephaly. This could be harmless, but it could also be a sign of a major neurological impairment and developmental delay.¹

"Macro" is the Greek word for large, and "cephaly" is Greek for head. Therefore, a big head size is referred to as microcephaly. Macrocephaly can be diagnosed in babies who are under the age of 3 years. It is required to measure the head circumference of an infant repeatedly, during each health supervision visit, in order to gauge the rate of head growth. Before beginning any form of treatment, any abnormal readings should be thoroughly investigated.¹

Overview

Macrocephaly means your baby’s head is larger than what is considered average for babies of the same age and sex. Having a larger head size can be harmless if it is inherited, but it can also be a sign of a significant medical condition. An enlarged brain, a brain haemorrhage (bleeding), excess fluid in the skull, and hereditary diseases are all common medical issues that can cause microcephaly. Treatments are specific to the cause.

Causes of macrocephaly

The main causes of this condition include having an increased amount of brain tissue (parenchyma), also known as megalencephaly, or having excess cerebrospinal fluid (CSF) surrounding the brain. It can also be caused by blood being present around the brain, thicker bones of the skull, or increased intracranial pressure (pressure within the skull).¹

These causes can be grouped as follows:²

• Hydrocephalus
• Overgrowth of skull bones
• Brain tumours
• Chronic (long-lasting) haematomas, which can be caused by head injuries
• Brain infections, such as meningitis, encephalitis or an abscess
• Genetic disorders, including achondroplasia, fragile X syndrome, neurofibromatosis type 1 and PTEN hamartoma tumour syndrome
• Increased intracranial pressure

Signs and symptoms of macrocephaly

The main symptoms associated with macrocephaly are:³

• Rapid head growth
• Bulging veins on your child’s head
• Developmental delays (not reaching learning milestones)
• Droopy eyelids
• Tense or bulging fontanelle (normal soft spots on a baby’s skull where the bones haven’t fully fused yet)
• Poor appetite
• Having other complications, such as epilepsy or autism
• Muscle-related conditions, such as spasticity or hypotonia
• Movement disorders, like ataxia, dystonia and gait abnormalities⁴

Management and treatment for macrocephaly

The treatment options to manage macrocephaly depend on the cause of the condition. The following options are available:⁴

• Neurosurgery: In certain cases of macrocephaly, surgery is the only treatment choice. The type of surgery will depend on the extent of brain swelling. The doctor may also prescribe oral medication to reduce brain tissue swelling before the medical procedure 
• Medications: Macrocephaly caused by hereditary (inherited) problems often has no cure. Infants with incurable macrocephaly may live with cognitive and physical disabilities, as well as seizures. Hence, treatment relies on managing symptoms with medication like anti-epileptic drugs
• No intervention: Benign familial macrocephaly requires no intervention other than serial head circumference measurement and reassurance

Diagnosis

In the first year of a baby's life, doctors will likely identify microcephaly during a normal exam by measuring the infant's height, weight, and head circumference. The following techniques will be used by doctors to look for the underlying problem that may be the cause of macrocephaly:⁴
 

• A physician will examine an infant externally, feeling the head and fontanelles
• Doctors will also check the baby for signs of irritability, a poor suckling reflex, extreme lethargy, and if any developmental milestones have been missed
• An ultrasound gives a quick analysis of what lies beneath the skull by imaging the brain
• CT scans are useful in examining the shape of the skull and identifying any skull deformities
• MRI uses a magnetic field to generate a highly accurate and elaborate image of the entire skull and brain
• A blood test may help assess the presence of genetic problems

Complications

Complications of macrocephaly may include:

• Brainstem compression is caused by an enlarged brain that does not have adequate room within your child's skull
• Hydrocephalus, which can be fatal if not treated promptly
• Seizures and epilepsy
• Developmental delays
• Abnormal brain function

Risk factors

Macrocephaly can also be caused by acquired hydrocephalus, which can be caused by cerebral haemorrhage or infection. Prematurity, subdural hematomas (which are usually caused by child abuse or birth trauma), and subdural effusions (which are caused by trauma or infection) are all risk factors for microcephaly.⁵

FAQs

Can macrocephaly be prevented?

Macrocephaly cannot be prevented. If the child is meeting overall developmental milestones and has normal neurologic function, it can be considered a normal and healthy condition.¹

How common is macrocephaly?

Macrocephaly is a clinical disorder that affects up to 5% of the paediatric population.³

What can I expect if my child has macrocephaly?

If your child has a larger-than-normal head, but otherwise meets normal developmental milestones and performs adequately on a neurologic exam, the macrocephaly can be considered benign, so no treatment is needed. If the condition results in serious conditions, then either surgery or medication may be required.⁶

When should I see a doctor?

You should contact your doctor if your child is showing any of these signs or symptoms:

• Bulging fontanelles
• Lack of appetite 
• Vomiting
• Unusual eye movements
• Being more sleepy and irritable than usual

Summary

Macrocephaly is a health condition in which a baby’s head circumference becomes larger than usual for their age. Excess brain fluid, infections, congenital brain conditions, or genetic disorders are primary causes of microcephaly. Physical examination, along with an MRI, ultrasound, or CT scan, are some of the methods used to diagnose macrocephaly. The usual treatments for macrocephaly include surgery or oral medication. However, genetic conditions cannot be cured and can only be managed.