In neonates, what does a tense fontanelle indicate?

A tense fontanelle in neonates is often associated with increased intracranial pressure, which can be a late sign of meningitis. Meningitis is characterized by inflammation of the protective membranes covering the brain and spinal cord, and in the case of increased pressure, the fontanelle may appear bulging and tense rather than flat.

This increase in intracranial pressure may not happen until the infection has significantly progressed, which is why it is considered a later sign rather than an early one. Early signs of meningitis typically include more subtle symptoms such as irritability, poor feeding, or fever, rather than changes in the fontanelle.

While a tense fontanelle can also be associated with other conditions—such as a subgaleal hemorrhage or other forms of intracranial bleeding—its presence is most classically linked to significant changes in the pressure within the cranial cavity, which is what makes it a late indicator of meningitis. A normal fontanelle should feel firm but not tense, indicating that there's no significant increase in intracranial pressure.