A concussion is a mild form of traumatic brain injury that temporarily affects how the brain functions, but it does not cause structural damage visible on standard imaging. The concussion itself does not breach blood vessels in the nasal passages, meaning it generally cannot cause a nosebleed. Instead, a nosebleed is almost always caused by a separate, concurrent injury to the face or skull that occurs at the same time as the concussive force. Understanding the distinct mechanisms of these two injuries is important for proper evaluation after head trauma.
Understanding the Concussion Mechanism
A concussion is primarily defined as a functional disturbance to the brain, not a gross structural injury that results in external bleeding. It is caused by the rapid acceleration and deceleration of the head, which generates forces that cause the brain to shift within the skull. This physical movement creates shear forces that stretch and damage the delicate neuronal axons and white matter tracts.
The damage in a concussion is on a microscopic, cellular level, leading to a cascade of ionic, metabolic, and physiological changes within the brain tissue. These changes disrupt the brain’s normal electrical and chemical balance, resulting in symptoms like confusion, dizziness, and headache. Since the injury is functional, the brain tissue remains intact, meaning there is no external pathway for blood to leak from the brain or skull into the nose or ears.
The symptoms of a concussion arise from this temporary disruption of neural function and altered cerebral blood flow. Therefore, a pure concussion, in isolation, lacks the physical mechanism necessary to cause a nosebleed. Concussion symptoms, such as headache or confusion, are separate from the mechanical trauma that would cause nasal bleeding.
Alternative Reasons for Nosebleeds After Head Trauma
A nosebleed, or epistaxis, occurring after a blow to the head is typically the result of direct trauma to the face or nose, which may happen concurrently with the concussive force. The nose is highly vascular, especially the nasal septum, where numerous small blood vessels sit close to the surface. A direct impact to the face can easily rupture these fragile vessels, leading to bleeding.
The force that causes the concussion often involves an impact point that includes the face, such as hitting the forehead or nose on a hard surface. This mechanical impact can cause a nasal bone or sinus fracture, which breaches the blood vessels within those bony structures and causes a nosebleed. In this scenario, the nosebleed is a sign of facial trauma, not a symptom of the brain injury itself.
In some cases, the body’s physiological response to trauma, including temporary increases in blood pressure, can cause minor, already injured nasal vessels to bleed more profusely. A more serious but less common cause is a fracture at the base of the skull, known as a basilar skull fracture. If a fracture line extends into the sinuses or nasal cavity, it can cause bleeding that appears as a nosebleed.
Critical Signs Indicating Severe Head Injury
While most nosebleeds after a head injury result from simple facial trauma, certain signs indicate an injury requiring immediate emergency care. The most concerning symptom is clear or yellowish fluid mixing with blood from the nose or ears. This fluid may be cerebrospinal fluid (CSF), which surrounds and cushions the brain and spinal cord.
A leak of CSF, known as CSF rhinorrhea, indicates a basilar skull fracture where the bony barrier has been broken. Other warning signs include heavy, uncontrollable bleeding that persists for more than 20 to 30 minutes despite applying pressure. Delayed bleeding, appearing days or weeks after the initial trauma, can signal a complicated injury, such as a developing pseudoaneurysm.
Other symptoms that signal a life-threatening brain injury, such as an intracranial hemorrhage, include significant changes in mental status, profuse vomiting, or the onset of seizures. Delayed signs of a skull base fracture include the appearance of deep bruising around the eyes (“raccoon eyes”) or behind the ears (Battle’s sign). Significant changes in mental status include:
Significant Changes in Mental Status
- Worsening confusion.
- Difficulty waking up.
- Slurred speech.
- Profound weakness or numbness in the limbs.
Seeking Medical Evaluation and Care
Any nosebleed following a head injury should prompt immediate medical evaluation to rule out underlying structural damage. If the nosebleed is accompanied by signs of severe injury, such as clear fluid leakage or loss of consciousness, emergency medical services should be contacted immediately.
For a nosebleed that is not accompanied by severe symptoms, first aid involves sitting upright and leaning slightly forward to prevent swallowing blood, which can cause nausea. Gentle, continuous pressure should be applied to the soft part of the nose for at least 15 minutes. An ice pack applied to the bridge of the nose may help constrict the blood vessels and reduce swelling.
If the bleeding does not stop after 15 minutes of continuous pressure or if it is recurrent, a medical professional must be consulted. Even if the nosebleed resolves quickly, an assessment is necessary to evaluate for a concussion and any potential underlying facial or skull fractures. A doctor will assess the symptoms to determine the injury’s severity and the appropriate course of action.