What is a subdural hematoma and how it is treated
A subdural hematoma—often called a subdural haematoma in Australian medical usage—is a collection of blood between the dura, the tough outer covering of the brain, and the arachnoid membrane beneath it. As the clot grows, it can compress brain tissue, raise intracranial pressure and cause the brain to shift inside the skull. Severe bleeding may become life-threatening without prompt treatment.
A blow to the head—often called a head knock in Australia—is the most common trigger. A fall or collision can tear small bridging veins, allowing blood to accumulate. Bleeding may also occur without a remembered injury, especially in older adults, people taking anticoagulants and those with conditions that cause brain atrophy.
This guide explains how a subdural hematoma is recognised, diagnosed and treated. Timing helps clinicians describe the bleed: acute usually means identified within 72 hours, subacute spans a longer interval, and chronic is often found weeks after the original event.
How a subdural hematoma forms
The dura is fixed tightly to the skull, while the arachnoid follows the brain’s contours. The gap between these layers accommodates bridging veins. When they tear, blood can collect without the obvious signs associated with some other brain injuries.
The amount and speed of bleeding influence symptoms. A rapid bleed can create major pressure within hours. A slower bleed may expand for weeks, especially when an injured brain has more space around it. The clot may also become organised, making later drainage harder.
Trauma is the leading cause, but spontaneous subdural hematomas occur in older people and patients with bleeding disorders. Anticoagulants and antiplatelet medicines increase bleeding risk, while brain atrophy, meaning shrinkage, and falls make injury more likely. Medication review is therefore an important part of assessment.
Signs that require urgent medical attention
Common symptoms include a severe or worsening headache, vomiting, drowsiness, confusion, slurred speech, one-sided weakness or numbness, seizures and reduced alertness. Some people lose consciousness; others remember little about the event. The neurological pattern can be uneven, so a new change from the person’s usual function matters.
Symptoms may be delayed, particularly in older adults and people taking anticoagulants. Someone may seem well after the injury before becoming confused, sleepy or unsteady. Repeated vomiting, a new inability to walk, unequal pupils, worsening weakness or reduced consciousness requires emergency assessment, even if the initial injury appeared minor.
In Australia, call Triple Zero (000) for an ambulance if symptoms are severe or rapidly worsening. Public hospital emergency departments assess people by clinical urgency, and a GP referral is not needed for emergency care. Breathlessness is not a defining feature of a subdural hematoma. Someone with asthma should still follow their asthma action advice while emergency care is arranged, without delaying the 000 call.
Diagnosing a subdural bleed
A non-contrast CT scan of the head is usually the first test because it can show bleeding quickly and reveal pressure on the brain. MRI may be used when the scan is normal but a subdural hematoma is still suspected, when the injury is more complex, or to assess its extent. The scan measures the clot’s thickness and any midline shift, which help guide treatment.
Doctors also perform a neurological examination and review the mechanism of injury. Blood tests may check clotting, and the medication list is examined for anticoagulants or antiplatelet drugs. After a significant accident, imaging of the neck or other injured areas may be needed because a head injury can occur alongside spinal trauma.
Specialist access varies across Australia. A GP can arrange imaging and referral; Medicare covers eligible public hospital treatment, while private insurance can affect the speed of elective specialist access. People in regional NSW, Far North Queensland or remote Western Australia may need transfer to a tertiary hospital, with telemedicine and retrieval services coordinating care. In the United States, patients can review the specialist services offered by Ocala Neurosurgical Center while following their local referral pathway.
Choosing treatment based on the clot
A small, stable hematoma in someone without neurological deterioration may be managed with observation, repeat imaging and close review. Medicines that increase bleeding may need to be stopped or reversed, depending on the drug and clinical assessment. Pain relief, seizure medicines when indicated and treatment of other medical problems are also important. Anyone on anticoagulants should not change their dose without medical advice.
Surgery is considered when the hematoma is large, symptoms are worsening, or scans show significant compression or brain shift. A burr-hole procedure drains blood through small openings in the skull. A craniotomy opens a larger section of skull and may be used to remove a substantial or organised clot, control bleeding and reduce pressure on the brain. Urgent neurosurgical treatment can be lifesaving.
These procedures differ from vertebroplasty and kyphoplasty, which stabilise collapsed vertebrae and relieve selected spinal compression fractures. A subdural hematoma requires assessment of the brain and its covering membranes, not treatment of the spinal bones. The choice between observation and surgery depends on the whole clinical picture, not a size measurement alone.
| Type | Typical time from injury | Main concern | Common approach |
|---|---|---|---|
| Acute | Within 72 hours | Rapid expansion and pressure on the brain | Emergency CT, urgent neurosurgical review, reversal of clotting medicines when appropriate, and drainage if indicated |
| Subacute | About 3 days to 3 weeks | Ongoing bleeding and a forming clot | Repeat imaging and close observation, with evacuation when symptoms, size or pressure is concerning |
| Chronic | More than 3 weeks | Long-standing compression that may cause subtle decline | CT or MRI, medication and fall-risk review, and surgery when symptoms or significant brain compression are present |
Timing is only one factor. Age, neurological function, anticoagulant use, brain shrinkage and the underlying cause of bleeding all influence decisions. A small clot can still require urgent care if the person is deteriorating, while a larger stable collection may be monitored by a specialist team. The goal is to prevent secondary brain injury while minimising the risks of treatment.
Recovery and taking the next step
Recovery depends on clot size, treatment timing and health before the injury. Headache, fatigue, concentration problems, memory changes, weakness or balance difficulties may improve over weeks but can require months of support. Physiotherapy, occupational therapy, speech therapy and neuropsychological assessment may help with mobility, daily tasks, communication and cognition.
Follow-up imaging may be needed, and the team should review seizures, pain, sleep, mood and medication effects. A second opinion can help when the diagnosis is uncertain, symptoms do not fit the expected course, or the reasons for surgery are unclear. Although it concerns the spine, the discussion of a spine surgery second opinion shows the value of reviewing imaging, records and specialist reasoning. Pet care can also complicate recovery at home. The community information in pets in the city illustrates how owners can plan local support, although Australians should search for services in their own area.
If symptoms are severe, new or worsening, call 000 now. If urgent symptoms have settled but headache, confusion, vomiting, balance problems or anticoagulant use remains concerning, arrange a prompt GP review and mention the injury. Ask for a neurosurgical opinion when indicated, and use the centre’s contact details to discuss whether further imaging, observation or specialist treatment is appropriate.