Large Head Size & Seizures

There are many reasons for people to have large heads. Large head sizes run in some families. People are sometimes born with large heads due to a malformed brain. Injuries or illness can cause swelling of the brain, or bleeding in the skull cavity. A large head size can often be normal, and a person can function normally, but at other times, a large head can be associated with seizures.

What Is a Seizure?

• Seizures, also known as convulsions, are abnormal electrical impulses within the brain. "A seizure occurs when part(s) of the brain receive a burst of abnormal electrical signals that temporarily interrupts normal electrical brain function," according to the Children's Hospital Boston. A seizure can cause effects including jerking motions of the arms or legs, smacking of the lips, twitching of the eyes, staring spells and loss of consciousness. Seizures are not necessarily life-threatening, but the underlying cause of the seizure can be serious.

What Causes Seizures?

• Seizures may be caused by head trauma, infection, malformation of the brain, metabolic disorders, poisons, fevers and more. They may be a symptom of a more concerning medical problem, such as hydrocephalus ("water on the brain") or intracranial bleeding. Before seizures can be properly treated, physicians need to identify the underlying cause. If the cause is not found thorough medical investigation, seizures may be considered "idiopathic."

What Is Considered a Large Head?

• Sometimes convulsions are associated with a large head size (macrocephaly). Macrocephaly is a head size that is considerably bigger when compared to people of the same age and gender. This condition can be completely normal, not causing any problems or untoward symptoms. Other times, people with large heads have seizures, developmental delays and mental retardation. The head circumference is routinely monitored during infancy, the period in which the brain has the most growth, and a medical investigation should be done if the infant's head grows too large or too quickly.

What Causes Heads to Be Large?

• Large heads can be due to an inherited family trait and can be completely benign. There can also be more serious causes for a large head size, such as brain malformations. In infancy, the skull bones may not have fused, allowing room for expansion if there is swelling or increased fluid on the brain. Some diseases or conditions such as trauma or infection may cause the brain to swell. Bleeding or excess cerebrospinal fluid may cause the head size to grow.

Does a Large Head Cause Seizures?

• Most often, the underlying cause of the enlarged head is the cause of the seizures as well. Tumors and cysts take up space inside the skull and cause pressure on the brain. Once the skull bones have fused at about 18 months of age, the head can no longer expand to accommodate increases in pressure, and seizures occur from the pressure on the brain. Other conditions, such as neurofibromatosis or hydrocephalus, may cause the head and brain to grow abnormally large, while also causing seizures.