When a person strikes their head against an object, the immediate result is the rapid formation of a noticeable lump, often called a “goose egg.” This common reaction is the body’s response to sudden impact. While a large, raised bump can cause concern, most minor head impacts that produce this swelling are not indicative of a severe underlying brain injury. The lump is a localized soft tissue injury.
How Impact Causes Localized Swelling
The unique anatomy of the scalp is the primary reason a head impact results in a pronounced, outward bump. The scalp is composed of several layers of skin and connective tissue, which are rich in tiny blood vessels. When blunt force hits the head, these small blood vessels are damaged and rupture, causing localized bleeding and fluid buildup.
The swelling occurs beneath the skin, specifically between the galea aponeurosis and the skull bone. Unlike other body areas, the tough skull prevents the fluid from spreading inward into surrounding tissues. This trapping of blood and inflammatory fluid forces the swelling outward, creating the dome-like shape of the “goose egg.” The medical term for this collection of clotted blood is a hematoma.
The rapid appearance of the lump is a direct consequence of this pooling of blood. The size of this external hematoma is related to the number of damaged blood vessels and the amount of blood trapped. Importantly, the size of the bump does not directly correlate with the degree of force transmitted to the brain beneath the skull.
Scalp Hematoma Versus Brain Injury
A superficial scalp hematoma must be distinguished from a more serious internal head injury, such as a concussion or intracranial hemorrhage. A hematoma is an injury to the soft tissues outside the skull, while a brain injury involves the brain tissue or spaces within the skull. The presence of an external bump does not reliably predict the severity of any underlying brain trauma.
A person can sustain a significant concussion or internal bleeding without developing a large scalp hematoma, especially if the impact caused rapid head rotation. Conversely, a large “goose egg” may form from a minor impact that causes extensive scalp bleeding but leaves the brain unaffected. Therefore, monitoring for internal symptoms is primary, rather than judging severity by the lump’s size.
Red Flags Requiring Medical Attention
Specific symptoms, often called “red flags,” indicate a serious brain injury and warrant immediate medical evaluation. These include:
- Loss of consciousness, even if brief.
- Persistent vomiting or nausea.
- A severe headache that progressively worsens.
- Slurred speech or profound confusion.
- Difficulty recognizing people or places.
- Unequal pupil sizes or signs of seizure activity.
- Weakness or numbness in the arms or legs.
- Clear fluid draining from the nose or ears.
Immediate Care and When to Seek Help
For a simple scalp hematoma without concerning internal symptoms, immediate care focuses on managing external swelling and pain. Applying a cold compress or ice pack wrapped in a thin towel to the bump as soon as possible can help. Cold temperatures constrict superficial blood vessels, limiting blood leakage into the tissue and reducing the final size of the swelling.
Rest is beneficial following any head impact. It is important to monitor the individual closely for the first 24 to 48 hours, allowing time for any delayed symptoms of a brain injury to manifest. Individuals should avoid strenuous activity and be watched for changes in behavior, sleep patterns, or cognitive function.
Immediate medical attention is mandatory if any red flag symptoms appear. This includes if the person becomes difficult to wake up, experiences repeated vomiting, or shows signs of significant confusion. Any head injury that occurs at high speed, such as a car crash or a fall from a significant height, also requires an immediate professional medical assessment, regardless of initial symptoms.