Macrocephaly is a symptom rather than a disease. To better understand it , consider that the head is a container, while the brain, meninges, cerebrospinalfluid, blood vessels, lymphatics and nerves as contents of that container.
IF any of the contents got enlarged in size; then the container will adapt to this by getting enlarged, what is known as macrocephaly.
What is the definition of macrocephaly?
It means enlarged size of the head two standard deviations from normal for age and sex.
Causes and differential diagnosis:
Causes of macrocephaly are categorized according to different classifications.
According to the pathological process underlying the cause (infection, genetic, familial…..etc) or
According to the anatomical structure that led to macrocephaly.
In general, the causes of macrocephaly are:
- Familial e.g.: Benign familial macrocephaly: The most common cause of macrocephaly. It runs in families and doesn’t lead to neurological deficit.
- Hydrocephalus: Because of excess volume of the cerebrospinal fluid, increased secretion of the fluid or obstructed drainage. The fluid will accumulate in the brain ventricles leading to enlargement of the head size with subsequent atrophy of the brain substance. Patient may have neurological troubles with the macrocephay, e.g.: epilepsy, cerebral palsy, and paresis or muscle paralysis.
- Infections: Central infections e.g.: meningitis and encephalitis.
- Genetic: Autism.
- Metabolic: Storage diseases.
- Bleeding: Intracranial haemorrhage, especially: subdural hematoma and intraventricular bleeding.
- Tumors: Like various brain tumours, vascular maleformations and arachnoid cyst.
- Chronic haematomas.
- Enlarged skull bones: e.g.: thalassemia, why? because of the associated expanded bone marrow.
- The first detection of the macrocephaly usually occurs during the last trimester of pregnancy or during early childhood, before closure of the cranial fontanels and sutures, when the skull bones are flexible for increasing size.
- The head circumference is larger than expected for age and sex by more than 2 standard deviations.
- Asymmetry of the cranium (both sides of the head are not identical).
- It is common to have developmental delay.
- Motor dysfunction e.g.: hemiparesis, hemiparalysis.
- There is slower growth of the body in relation to the head.
- Autism or epilepsy may accompany it.
- Symptoms and signs of increased intracranial pressure: vomiting, Headache and papilledema (raised optic disc seen during fundus examination of the eye).
- Usually, the anterior fontanel is raised and wide.
- Delayed closure of the posterior fontanel.
- Skeletal deformities.
Diagnosis of macrocephaly:
Physicians diagnose it clinically by measuring the head circumference, but the physician and the patient or relatives need to know what the exact cause of the condition is, and what are the associated structural abnormalities?
To determine the best method to treat the patient’s condition.
Imaging of macrocephaly:
- Plain X-Ray of the skull.
- Ultrasound on the anterior fontanel of baby.
- Computed tomography (CT) brain: It is the best imaging study for diagnosing macrocephaly.
- Magnetic resonance imaging (MRI) brain.
It depends on the accurate identification of the cause of macrocephaly, as the treatment should target the specific abnormality to treat it and to prevent its complications.
- Benign familial macrocephaly: No need to treat it.
- Hydrocephalus: It needs surgical treatment in the form of ventriculostomy or ventriculoperitoneal shunt. The aim of those surgeries is to drain the excess cerebrospinal fluid to the peritoneal cavity.
- Medical treatment of macrocephaly: e.g.: Antibiotics, anticonvulsants for epilepsy.
- Physiotherapy: To determine the accompanying motor troubles and stiffness.