From the Guidelines
Macrocephaly is primarily caused by a variety of factors including megalencephaly, hydrocephalus, enlargement of extra-axial spaces, and skeletal dysplasia, with the most common causes being familial macrocephaly, hydrocephalus, brain tumors, or neurodevelopmental disorders. When evaluating macrocephaly, it is essential to consider the underlying cause, as it can significantly impact treatment and outcomes. According to the study by 1, macrocephaly may be related to a wide variety of causes other than megalencephaly, including hydrocephalus, enlargement of extra-axial spaces, and skeletal dysplasia.
Some key points to consider when evaluating macrocephaly include:
- Macrocephaly is defined as an OFC ≥2 s.d. above the mean, whereas megalencephaly refers to an abnormally large brain size, as stated in the study by 1.
- Mild megalencephaly (2–3 s.d. above the mean) with an otherwise structurally normal brain can be seen in typically developing children, often in the setting of benign familial macrocephaly, as noted in the study by 1.
- Megalencephaly can point to an underlying neurodevelopmental or generalized overgrowth disorder, highlighting the importance of thorough evaluation and diagnosis.
- Treatment depends entirely on the underlying cause, ranging from monitoring for familial macrocephaly without symptoms to surgical intervention for hydrocephalus or specific treatment protocols for brain tumors.
In terms of diagnosis, doctors typically measure head circumference and compare it to growth charts, potentially ordering imaging studies like MRI or CT scans to investigate the cause, as seen in the study by 1. Parents should seek medical attention if they notice rapid head growth, developmental delays, or neurological symptoms like seizures, vomiting, or irritability, as early diagnosis and intervention are crucial to prevent developmental issues or increased intracranial pressure if left untreated.
From the Research
Causes of Macrocephaly
The cause of macrocephaly, also known as abnormal enlargement of the head, can be related to hydrocephalus, a condition characterized by an imbalance of cerebrospinal fluid (CSF) formation and absorption 2, 3, 4.
- Hydrocephalus can be caused by various factors, including:
- Obstruction of CSF pathways, resulting in occlusive hydrocephalus 3
- Impaired CSF absorption, leading to malabsorptive hydrocephalus 3
- Genetic mutations 4
- Post-traumatic injury 4
- Inflammatory processes 2, 3
- Intraventricular hemorrhage in the perinatal period, particularly in children under two years old 2
Relationship between Hydrocephalus and Macrocephaly
In children under two years old, hydrocephalus can cause progressive enlargement of the head and widened anterior fontanel, which can be a sign of macrocephaly 2.
- Imaging examinations, such as computed tomography (CT) and magnetic resonance (MR) images, are essential in diagnosing hydrocephalus and assessing the enlargement of the ventricular system 2, 3, 5
- The treatment of hydrocephalus depends on the type and cause of the condition, and may involve surgical procedures, such as ventriculocisternostomy or VP shunts 2, 4, 5