Last Updated on February 9, 2023 by Mike Robinson

Definition of Macrocephaly

Macrocephaly is a neurological disorder in which there is an abnormal increase in the size of the head (National Institute of Neurological Disorders and Stroke, 2015).

Specifically, there is an increase in the cranial perimeter. That is, the distance around the largest area of the skull is greater than expected for the age and sex of the affected person (National Institutes of Health, 2015).

At a more clinical level, macrocephaly occurs when the perimeter or cranial circumference exceeds the mean of that age and sex by two standard deviations or is greater than the 98th percentile (Erickson Gabbey, 2014).

These signs can be evident from birth or develop in the first years of life (National Institute of Neurological Disorders and Stroke, 2015).

It is a rare condition that affects men more often than women (National Institute of Neurological Disorders and Stroke, 2015).

Although not all cases of macrocephaly are cause for alarm, it is often accompanied by various symptoms or medical signs, including generalized developmental delay, seizures, and corticospinal dysfunction, among others (National Institute of Neurological Disorders and Stroke, 2015).

Characteristics of Macrocephaly

Macrocephaly is a poor neurological condition in the category of disorders of head growth.

In the pathologies or disorders of the cranial growth, cranial size anomalies occur due to different alterations in the bones of the cranial vault or the Central Nervous System (Mart Herrero & Cabrera López, 2008).

Specifically, macrocephaly is an abnormal increase in the cranial perimeter above the expected value for the age and sex of the affected person (Garca Peas & Romero Andjar, 2007).

This alteration can be due to an excess of cerebrospinal fluid volume, an increase in brain size, or even a thickening of the cranial vault (Garca Peas & Romero Andjar, 2007).

Although many patients affected by macrocephaly do not present significant signs or symptoms derived from the pathology, many others present important neurological anomalies.

Statistics

There are no specific statistical data on the prevalence of macrocephaly in the general population.

However, clinical studies consider it a rare or uncommon pathology that occurs in approximately 5% of the population. 

(Mallea Escobar et al., 2014).

It is usually a disorder that affects a greater proportion of the male sex and is usually present at birth or develops in the first 

years of life, so it is common to have child macrocephaly.

Symptoms 

Derived from the definition of this pathology, the most characteristic symptom of macrocephaly is an abnormally large head size.

As in the case of other pathologies or disorders that affect cranial growth, the size of the head takes place around the circumference or cranial perimeter, the measurement of the contour of the head at the top (Microcephaly, 2016).

The growth of the brain determines the size of the head or skull, the volume of cerebrospinal fluid (CSF) or blood, and the bone thickness of the skull (Mallea Escobar et al., 2014).

A variation in any of these factors may cause significant neurological consequences; therefore, control and measurement of the growth of the cranial perimeter must occur in newborns and children, especially during the first years of life (Mallea Escobar et al., 2014).

The standard patterns of growth show us the following values (Mallea Escobar et al., 2014):

– Cranial perimeter in term newborns: 35–36 cm.

– Approximate growth of the cranial perimeter during the first year of life: approximately 12 cm, more accentuated in males.

– The speed of increase of the cranial perimeter during the first three months of life: approximately 2 cm per month.

– Speed of increase of the cranial perimeter during the second quarter of life: approximately 1 cm per month.

– Speed of increase of the cranial perimeter during the third and fourth quarters of life: around 0.5 cm per month.

The values obtained from the measurement of the size of the head in medical and sanitary controls should be compared with a standard or expected growth chart. Children with macrocephaly present values significantly higher than the average of their age and sex.

Due to the different etiologies that give rise to the increase in the size of the head, different medical complications may appear that affect both the neurological functioning and the general functional level of the affected person.

Possible Complications

The medical conditions associated with macrocephaly will depend on the etiological cause; despite this, there are some frequent clinical manifestations (Mart Herrero & Cabrera López, 2008):

• Asymptomatic macrocephaly
• Convulsive episodes
• Generalized delay in development, cognitive and intellectual deficits, hemiparesis, etc.
•  Vomiting, nausea, headache, drowsiness, irritability, lack of appetite.
• Signs of endocranial hypertension, anemia, biochemical alterations, and systemic bone pathologies.

Causes of Macrocephaly

As we noted earlier, macrocephaly may appear due to alterations affecting brain size, cerebrospinal fluid volume, or bone abnormalities.

One of the publications of the Spanish Association of Pediatrics about macro- and microcephaly makes a detailed classification of the possible etiological causes of macrocephaly (Mart Herrero & Cabrera López, 2008):

Brain and cerebrospinal fluid (CSF) pathology

In the case of macrocephaly, due to the presence or development of cerebral pathology and cerebrospinal fluid, a macrocephaly of primary or secondary origin may also be present.

Primary macrocephaly

Primary microcephaly occurs due to an increase in brain size and weight.

Generally, a greater number of nerve cells or a larger size can be present in this type of microcephaly. When the presence of this etiological cause is determined, the pathology is called macrocephaly.

This type of alteration usually has a genetic origin; therefore, macrocephaly and hemimegalencephaly are part of this classification.

In addition, it is common for macrocephaly to form the set of clinical manifestations of other pathologies such as bone dysplasias, fragile X, Sotos syndrome, Beckwith syndrome, chromosomopathies, etc.

Secondary macrocephaly

Secondary macrocephaly also called progressive or evolving macrocephaly, may be due to changes in cerebrospinal fluid volume, such as lesions or occupant substances.

Increase in the level and volume of cerebrospinal fluid (CSF): abnormalities in the production, drainage, or reabsorption of cerebrospinal fluid can cause an accumulation of this and therefore lead to hydrocephalus.

The presence of occupant injuries refers to the presence of intracerebral structural and vascular malformations, masses, or collections. Some pathologies that give rise to this type of injury are cysts, tumors, bruises, arteriovenous malformations, etc.

– Presence of unnatural substances: this alteration refers to metabolic or deposit diseases such as Alexander’s disease, Canavan’s disease, metabolopathies, etc.

Bone abnormalities

As for the cases of macrocephaly that are due to bone abnormalities, we can find:

– Macrocephaly due to an early closure of cranial sutures.

– Macrocephaly due to systemic bone alterations: rickets, osteogenesis, osteoporosis, etc.

Diagnosis

Macrocephaly is a neurological pathology that can be detected during the gestation phase.

Routine health checks through ultrasound can detect abnormalities in cranial growth during the early stages of gestation when macrocephaly presents a congenital or prenatal origin.

However, it is not always possible to detect it before birth because many cases of macrocephaly occur secondary to other medical conditions.

It is usually detected in pediatric consultations by measuring the cranial perimeter. In addition, different neurological analyses must also take place to determine the etiological cause.

Specifically, the clinical examination should include the following (Mart Herrero & Cabrera López, 2008):

Physical exploration of the skull: an accurate measurement of the cranial perimeter and a comparison with the growth standards must occur.

Neurological examination: it will also be necessary to evaluate different neurological factors (gait, motor coordination, sensory deficits, cerebellar signs, reflexes, etc.).

Pediatric examination: in this case, it will focus on studying the etiological cause of macrocephaly through the analysis of genetic and neurological pathologies, etc.

Complementary examinations: In addition to the physical and neurological examination, additional explorations, such as magnetic resonance imaging, computed tomography, X-rays, lumbar puncture, electroencephalography, etc., may be required, especially in that macrocephaly of unknown origin.

Can Macrocephaly Be Treated?

At present, there is no curative treatment for macrocephaly. Generally, the treatment is symptomatic and will depend on the precise etiology diagnosis.

After detecting macrocephaly, it is necessary to determine the underlying cause to design the best therapeutic approach since, in cases where hydrocephalus is the leading cause of macrocephaly, it will be necessary to use surgical interventions.

Therefore, the treatment will have a marked palliative value. Pharmacological approaches for controlling medical complications are used, as well as non-pharmacological approaches to address the neurological and cognitive sequelae.

In all cases of macrocephaly and other types of alterations in cranial development, a neurological and, or neuropsychological examination must take place to examine the level of general functioning: developmental deficits, cognitive functions, linguistic deficits, motor skills, etc. (National Institute of Neurological Disorders and Stroke, 2016).

Some of the non-pharmacological interventions available in the symptomatic cases of macrocephaly are (Mart Herrero & Cabrera López, 2008):

• Neuropsychological rehabilitation
• Early stimulation
• Special education
• Occupational therapy

Forecast

The prognosis and evolution of this pathology depend fundamentally on its origin and associated symptomatology.

In children suffering from benign macrocephaly, the absence of symptoms or significant medical complications will allow them to develop all areas normally (Erickson Gabbey, 2014).

Also read State of Minimum Consciousness: Symptoms, Causes, and Treatments.

However, in many other cases, future perspectives will depend on medical complications (Erickson Gabbey, 2014). In general, children suffering from macrocephaly will present significant delays in generalized development and, therefore, will require therapeutic intervention to promote the acquisition of new skills and achieve an efficient functional level.