Brain Bleeds After a Head Injury

Quick answer

A head injury can cause bleeding inside the skull, either in the brain tissue or in the layers that surround the brain.[1] The main types linked to trauma are epidural hematoma, subdural hematoma, subarachnoid hemorrhage and bleeding within the brain itself (contusions and intracerebral hematomas).[1][2] In a study of 5,634 people with mild TBI who had a head CT, 4.7% of scans showed a subdural hematoma and 4.5% showed a traumatic subarachnoid hemorrhage.[3]

The layers around the brain

NINDS explains that the brain is surrounded by three protective membranes: the dura mater (outermost), the arachnoid mater (middle) and the pia mater (innermost). Different types of hematomas form depending on where blood collects in relation to these layers.[9]

Main types

Epidural

Between the skull and the dura.[4]

Subdural

Between the dura and the arachnoid, on the brain’s surface.[9]

Subarachnoid

Between the arachnoid and the pia.[9]

Intracerebral

Within the brain tissue itself.[9]

Epidural hematoma

MedlinePlus describes an epidural hematoma as bleeding between the inside of the skull and the dura.[4] It is often caused by a skull fracture during childhood or adolescence, and can also result from rupture of a blood vessel, usually an artery.[4] MedlinePlus notes that less severe blunt trauma, such as being hit by a baseball, can also cause one.[4] NINDS describes epidural hematomas as particularly dangerous and able to develop within minutes to hours after injury.[9]

MedlinePlus notes a well-known pattern in which a person briefly loses consciousness, then becomes alert, then loses consciousness again, though this pattern does not appear in everyone.[4] According to MedlinePlus, an epidural hematoma is an emergency condition, emergency surgery is often necessary, and there is a high risk of death without prompt surgical treatment.[4]

Subdural hematoma

A subdural hematoma is a collection of blood between the dura and the surface of the brain.[5] MedlinePlus explains that it happens when tiny veins between the surface of the brain and the dura stretch and tear, allowing blood to collect.[5]

Acute

Usually caused by a severe head injury. MedlinePlus describes acute subdural hematomas as among the deadliest of all head injuries.[5]

Chronic

More common in older adults and can follow a minor head injury. It can go unnoticed for many days.[5]

MedlinePlus lists risk factors including medicines that thin the blood (such as warfarin or aspirin), long-term alcohol use, conditions that make blood clot poorly (such as kidney or liver disease), repeated head injury such as from falls, and being very young or very old.[5] MedlinePlus notes that emergency surgery may be needed to relieve pressure, either by drilling a small hole in the skull to drain blood or, for large hematomas or solid clots, by a craniotomy.[5]

Traumatic subarachnoid hemorrhage

A review of TBI neuropathology describes bleeding into the subarachnoid space as the most common form of vascular injury after head trauma.[6] An NCBI Bookshelf chapter on TBI imaging notes that traumatic subarachnoid hemorrhage without other bleeding generally carries less risk of rapid deterioration or need for surgery.[2] However, a 2024 TRACK-TBI study in the Journal of Neurotrauma found that 46% of patients with isolated traumatic subarachnoid hemorrhage on CT had additional injuries visible only on MRI.[7]

Subarachnoid hemorrhage can also happen without trauma, most often from a ruptured aneurysm.[8] This site covers the traumatic form.

Contusions and intracerebral bleeding

MedlinePlus notes that the brain can be bruised when it hits the inside of the skull, and that bleeding can occur within the brain tissue itself.[1] NINDS describes contusions as bruising or swelling of the brain that happens when very small blood vessels bleed into brain tissue, and describes an intracerebral hematoma as bleeding into the brain itself that damages the surrounding tissue.[9]

Learn more: Traumatic brain injury · Types of head injuries

How common each type is

A 2020 study in Cureus reviewed head CT results for 5,634 people with mild TBI (GCS 13 to 15) at a Los Angeles Level I trauma center. It found:[3]

  • Acute subdural hematoma in 4.7% of scans
  • Traumatic subarachnoid hemorrhage in 4.5%
  • Hemorrhagic contusion or intracerebral hematoma in 3.8%
  • Epidural hematoma in 0.8%
  • Intraventricular hemorrhage in 0.4%

A single scan can show more than one type of bleeding.

How they’re found

NINDS notes that CT imaging can show a skull fracture and any brain bruising, bleeding or swelling, and that MRI is more sensitive to subtle changes.[9] MedlinePlus states that a non-contrast head CT confirms an epidural hematoma, and that a CT or MRI is done when a subdural hematoma is suspected.[4][5] The NCBI imaging chapter notes that certain MRI sequences can detect small amounts of subarachnoid blood and signs of past bleeding.[2]

Differences by age

According to MedlinePlus, epidural hematomas are often associated with skull fractures in childhood or adolescence, while chronic subdural hematomas are more common in older adults.[4][5] MedlinePlus explains that in older adults, the veins are often already stretched because of brain shrinkage (atrophy) and are more easily injured.[5] NINDS notes that subdural hematomas are very common in older adults after a fall.[9]

If someone else caused the injury

Brain bleeds after crashes, falls on someone else’s property or assaults can lead to surgery, long hospital stays and lasting effects. Imaging reports and surgical records are often central evidence. See Legal help after a head injury.

This page provides general information from the sources listed below. It is not medical advice and is not a substitute for evaluation by a qualified healthcare provider. In an emergency, call 911.

Sources

  1. MedlinePlus Medical Encyclopedia. “Head injury – first aid.” https://medlineplus.gov/ency/article/000028.htm
  2. “Neuroimaging Update on Traumatic Brain Injury.” NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK608606/
  3. Bonney PA, et al. “Rate of Intracranial Hemorrhage After Minor Head Injury.” Cureus, 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7586355/
  4. MedlinePlus Medical Encyclopedia. “Epidural hematoma.” https://medlineplus.gov/ency/article/001412.htm
  5. MedlinePlus Medical Encyclopedia. “Subdural hematoma.” https://medlineplus.gov/ency/article/000713.htm
  6. “The neuropathology of traumatic brain injury.” PubMed Central. https://pmc.ncbi.nlm.nih.gov/articles/PMC4694720/
  7. Yue JK, et al. “Isolated Traumatic Subarachnoid Hemorrhage on Head Computed Tomography Scan May Not Be Isolated: A TRACK-TBI Study.” Journal of Neurotrauma, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11564841/
  8. “Educational Case: Cranial hemorrhage and traumatic brain injury.” PubMed Central. https://pmc.ncbi.nlm.nih.gov/articles/PMC9123211/
  9. National Institute of Neurological Disorders and Stroke. “Traumatic Brain Injury (TBI).” https://www.ninds.nih.gov/health-information/disorders/traumatic-brain-injury-tbi

Sources last checked: October 11, 2026

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