Yes. A subdural hematoma (SDH) — a collection of blood that forms between the dura mater (the outer covering of the brain) and the brain's surface — is classified as a form of traumatic brain injury (TBI) when it results from a head injury. It occurs when the bridging veins that cross this space are torn, most often due to a blow to the head, a fall, a motor vehicle accident, or violent shaking (as in some cases of abusive head trauma in infants).
That said, not every subdural hematoma is caused by trauma. SDHs can also arise "spontaneously" or from non-traumatic causes, including:
- Rupture of a blood vessel abnormality (such as an aneurysm or arteriovenous malformation)
- Blood-thinning medications or bleeding disorders
- Brain tumors
- Sudden drops in cerebrospinal fluid pressure (for example, after a lumbar puncture or spinal surgery)
When the cause is unclear or non-traumatic, doctors may classify it separately from TBI, but the traumatic form is far more common, especially in older adults, where even a minor fall or bump can cause bleeding — sometimes because brain tissue naturally shrinks with age, stretching the bridging veins and making them more fragile.
SDHs are further categorized by how quickly symptoms appear:
- Acute SDH: Symptoms develop rapidly, usually within 24-72 hours of a significant head injury; this is a medical emergency often requiring surgery.
- Subacute SDH: Symptoms emerge over several days to weeks.
- Chronic SDH: Symptoms develop slowly over weeks to months, sometimes after a seemingly trivial or forgotten injury, and is more common in older adults or people on anticoagulant medication.
Symptoms can include headache, confusion, dizziness, weakness on one side, slurred speech, seizures, or loss of consciousness. Because bleeding can worsen over time, any suspected SDH — traumatic or not — warrants prompt medical evaluation, typically with a CT or MRI scan.