The term “melon baby” is a non-medical, colloquial phrase sometimes used to describe infants affected by hydrocephalus. This informal language refers to the noticeable enlargement of the head that can occur in young children due to the condition. Hydrocephalus involves an abnormal accumulation of fluid within the brain.
Defining Hydrocephalus
Hydrocephalus involves the buildup of cerebrospinal fluid (CSF) within the ventricles, the fluid-filled cavities deep inside the brain. The term is derived from Greek words meaning “water” and “head,” though the fluid is CSF. This clear, colorless fluid normally flows through the brain and spinal cord, cushioning the brain, delivering nutrients, and removing waste.
The body continuously produces and reabsorbs CSF, maintaining a careful balance. When this fluid circulation is disrupted, the excessive accumulation causes the ventricles to widen. In infants, whose skull bones have not yet fused, this increased internal pressure can cause the head to rapidly enlarge, a distinct physical sign.
Sources of Fluid Buildup
The excessive CSF accumulation results from an imbalance between the production and absorption of the fluid, often due to a blockage in its circulatory pathways. Hydrocephalus is broadly categorized into congenital (present at birth) and acquired (developing later in life). Congenital causes include developmental malformations that impede fluid flow, such as Aqueductal Stenosis, a narrowing of the passage between the third and fourth ventricles. Structural issues, like neural tube defects such as Spina Bifida, are also associated with the condition.
Acquired hydrocephalus develops after birth due to various injuries or diseases. Common acquired causes include infections, such as meningitis, which can scar the tissues responsible for CSF reabsorption. Head trauma, hemorrhage (bleeding) in the brain, or tumors can also physically obstruct the normal flow of the fluid.
Diagnosis and Management
Diagnosis often begins with physical signs in an infant, such as an unusually large head or a bulging soft spot (fontanel) on the skull. Prenatal ultrasounds can sometimes identify the condition before birth, and post-birth imaging studies confirm the diagnosis. A computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan provides detailed images of the brain’s ventricles, helping doctors assess the fluid buildup and identify the underlying cause.
The primary treatment for hydrocephalus is surgical intervention to divert the excess CSF and relieve pressure on the brain. The most common procedure is the insertion of a shunt system, a long, flexible tube with a valve. This device drains the excess fluid from the brain’s ventricles to another body cavity, such as the abdomen, where it is safely absorbed. For specific obstructions, an alternative procedure called Endoscopic Third Ventriculostomy (ETV) may be performed, creating a new pathway for the CSF to flow.