A soft spot, also known as a fontanelle, is an area on a baby’s head where the skull bones have not yet fused together. Babies are typically born with two main fontanelles: a larger, diamond-shaped one at the top-front of the head (anterior fontanelle) and a smaller one at the back (posterior fontanelle). These soft spots are a normal and important feature of infant development, allowing the skull to compress during passage through the birth canal and providing space for the rapid growth of the brain during the first year of life. A normal fontanelle should feel relatively soft and either flat or slightly curved inward, and it may gently pulsate with the baby’s heartbeat.
What a Bulging Soft Spot Looks Like
A bulging soft spot appears as a raised or mounded area on the baby’s head, elevated above the surrounding skull. When touched, it feels tense, firm, or taut, rather than soft and pliable. The skin over a bulging fontanelle might also appear stretched or shiny. This appearance is distinct from a temporary slight bulge that can occur when a baby is crying, coughing, vomiting, or straining, which typically flattens and returns to normal once the baby calms down or is in an upright position. A true bulging fontanelle remains elevated and does not resolve quickly.
Common Reasons for a Bulging Soft Spot
A bulging soft spot often indicates increased pressure inside the skull, which can stem from various underlying medical conditions. One common cause is hydrocephalus, a condition where excessive cerebrospinal fluid accumulates in the brain’s ventricles, leading to increased pressure. Infections affecting the brain or its surrounding membranes, such as meningitis (inflammation of the membranes covering the brain and spinal cord) or encephalitis (brain inflammation), can also cause the fontanelle to bulge due to swelling. Head trauma, including internal bleeding or swelling within the brain, can result in a bulging soft spot. In some rarer instances, a bulging fontanelle may be associated with conditions like brain tumors or abscesses that occupy space and increase intracranial pressure.
When to Get Medical Help
A bulging soft spot is considered a medical emergency and warrants immediate attention from a healthcare professional. Parents or caregivers should seek emergency medical care if they notice a persistent bulging fontanelle. This is especially important if the bulging is accompanied by other symptoms such as fever, excessive drowsiness, unusual irritability, persistent vomiting, poor feeding, seizures, a stiff neck, or noticeable changes in the baby’s alertness or behavior. Even if no other severe symptoms are present, any concern about a persistently bulging soft spot should prompt a medical evaluation. Prompt diagnosis and treatment are important for conditions that cause a bulging fontanelle, as delays can lead to serious health issues.