Subdural haematoma – Diagnostics – Overview of Information and Clinical Research

A subdural haematoma is a serious medical condition where blood accumulates between protective layers covering the brain, most often following a head injury. The condition can develop immediately or weeks after trauma, making early recognition and proper diagnostic testing essential for successful treatment and recovery.

Introduction: Who Should Undergo Diagnostics and When

Anyone who has experienced a head injury should be vigilant about unusual symptoms and seek medical evaluation promptly. Getting immediate medical help after a head injury is crucial, even if the injury seems minor at the time. You should not delay seeking care, as subdural haematomas can become life-threatening without proper diagnosis and treatment.^[1]

You need to go to the emergency department if you or someone you know has had a head injury and shows signs such as being knocked unconscious, vomiting after the injury, persistent headache that does not improve with painkillers, or changes in behaviour like increased irritability. In children under five, unusual crying or loss of interest in surroundings should prompt immediate evaluation. If you have a blood clotting disorder such as haemophilia, take blood-thinning medicines, or have had brain surgery previously, even seemingly minor head injuries require medical assessment.^[2]

Certain groups face higher risk and should be especially alert to symptoms. People aged 65 and older are at increased risk for subdural haematomas, even from minor head injuries. This happens because as the brain naturally shrinks with age, the space between the brain and skull grows larger, stretching the bridging veins that can tear more easily. In older adults, bleeding can occur slowly, and symptoms may not appear for weeks or even months after a seemingly insignificant knock to the head.^[1]

Young children and infants also require careful monitoring after any head trauma. In babies, a subdural haematoma may cause the head to enlarge because their soft skull can expand as blood collects. Signs like bulging soft spots on the skull, separated skull bones where they normally join, feeding difficulties, a high-pitched cry, persistent vomiting, or increased sleepiness all warrant immediate medical attention.^[4]

⚠️ Important

Call emergency services immediately if someone has hit their head and shows signs such as being knocked out and not waking up, difficulty staying awake, seizures, numbness or weakness in any body part, problems with vision or hearing, bleeding from ears, or clear fluid coming from ears or nose. These symptoms indicate a medical emergency requiring urgent care.^[2]

Sometimes people experience no symptoms immediately after a head injury. This period without symptoms is called a lucid interval. Symptoms may then develop days later, which makes ongoing observation important even after seemingly recovered from the initial trauma. Additionally, chronic subdural haematomas that develop slowly might be mistaken for other conditions such as brain tumours, stroke, or dementia, making proper diagnostic testing essential for accurate identification.^[1]

Diagnostic Methods for Identifying Subdural Haematoma

When doctors suspect a subdural haematoma, they begin with a careful physical examination. Your healthcare provider will ask detailed questions about your medical history, including any recent head injuries, even minor ones. They will check your brain and nervous system function by assessing balance, coordination, mental functions, sensation, strength, and walking ability. This examination helps identify problems that might indicate bleeding in the brain.^[4]

The physical examination includes checking pupillary reflexes, which means looking at how your pupils respond to light. Abnormal pupillary reflexes can indicate increased pressure on the brain. Doctors also look for focal neurological deficits, which are problems affecting specific body parts, such as weakness on one side of the body or changes in speech. They assess for signs of raised intracranial pressure (pressure inside the skull), including severe headaches, vomiting, and altered consciousness.^[14]

Brain Imaging Scans

If there is any suspicion of a haematoma based on symptoms or physical examination, doctors will order imaging tests. These tests create pictures of the inside of your head and brain, allowing doctors to see if blood has collected between the protective layers covering the brain.^[4]

A computed tomography scan, commonly called a CT scan, is typically the first and most important imaging test used to diagnose subdural haematoma. This test combines multiple X-ray images taken from different angles around your body. A computer then processes these images to create cross-sectional pictures, or slices, of your brain tissue and skull bones. The CT scan shows doctors where blood has accumulated, how large the collection is, and whether it is putting pressure on brain structures.^[7]

The appearance of blood on a CT scan changes over time, which helps doctors determine when the bleeding occurred. Acute subdural haematomas less than 72 hours old appear bright or white on CT scans because fresh blood is dense. Chronic subdural haematomas that have been present for weeks appear darker than the surrounding brain tissue. Sometimes doctors see mixed densities, indicating new bleeding has occurred into an older haematoma.^[8]

Magnetic resonance imaging, or MRI, uses powerful magnets and radio waves instead of X-rays to create detailed images of brain tissues. An MRI scan is sometimes ordered in addition to or instead of a CT scan. MRI provides more detailed information about the brain tissue itself and can be particularly helpful when doctors are planning treatment for chronic subdural haematomas. The detailed images from MRI help neurosurgeons predict which treatment approach will be most effective and has the lowest chance of the haematoma returning in the future.^[12]

Additional Diagnostic Tests

Healthcare providers may order blood tests to check how well your blood clots. These tests, called a coagulation profile, measure substances in your blood that help it clot properly. This information is important because people taking blood-thinning medications or those with bleeding disorders may require special management. Knowing your clotting status helps doctors plan treatment and may guide decisions about reversing the effects of blood-thinning medications.^[13]

In some cases, doctors might measure the pressure inside your skull. This test, which checks intracranial pressure, helps determine how much the blood collection is pressing on your brain. The measurement guides treatment decisions, particularly about whether surgery is needed urgently. High intracranial pressure can be dangerous because it prevents the brain from receiving adequate blood flow and oxygen.^[8]

Distinguishing Subdural Haematoma from Other Conditions

Doctors must distinguish subdural haematomas from other types of bleeding in the head. An epidural haematoma occurs when blood collects between the skull and the outermost protective layer, usually from torn arteries rather than veins. This type typically develops faster and appears differently on scans. A subarachnoid haemorrhage involves bleeding into a different space between protective layers or may occur after an aneurysm ruptures. These different types of brain bleeding require different treatments, making accurate diagnosis essential.^[6]

Chronic subdural haematomas developing slowly over weeks can produce symptoms similar to other brain conditions. Memory problems, confusion, and personality changes might suggest dementia. Sudden weakness might resemble a stroke. Persistent headaches and confusion could indicate a brain tumour. Only proper imaging tests can definitively identify a subdural haematoma and distinguish it from these other conditions.^[1]

Diagnostics for Clinical Trial Qualification

While this article focuses on routine diagnostic approaches for subdural haematoma, clinical trials investigating new treatments or surgical techniques would typically require standard diagnostic confirmation through CT or MRI imaging. Trial protocols would specify imaging criteria such as haematoma size, location, and whether acute, subacute, or chronic. Participants would need documented head injury history and neurological assessment results. Blood tests confirming coagulation status would be standard, particularly for trials involving patients on anticoagulant medications. Baseline imaging and neurological examinations would establish the starting point for measuring treatment outcomes.^[8]

Eligibility criteria would depend on the specific intervention being studied. Trials might focus on particular patient groups, such as elderly patients with chronic subdural haematomas, or specific treatments like comparing different surgical approaches. Standardized neurological assessments, such as the Glasgow Coma Scale score which measures consciousness level, would help classify injury severity consistently across participants. Follow-up imaging at defined intervals would track haematoma resolution and detect recurrence.^[13]

Prognosis and Survival Rate

Prognosis

The outlook for people with subdural haematomas depends on several important factors. The type of haematoma significantly affects outcomes. Acute subdural haematomas, which develop rapidly after severe head injury, carry high rates of mortality and serious brain injury even with prompt medical and surgical care. This poor prognosis occurs because acute haematomas are often associated with extensive underlying brain injury. In one study, 82 percent of comatose patients with acute subdural haematomas had bruising of the brain tissue itself, and the severity of this brain injury strongly determines the patient’s outcome.^[8]

Chronic subdural haematomas generally have better outcomes in most cases. When diagnosed and treated appropriately, many patients with chronic haematomas experience resolution of symptoms after the blood collection is drained. However, recovery can be difficult both physically and emotionally. Some patients with serious subdural haematomas face long-term or permanent problems affecting walking, talking, and thinking. They may also develop seizures that require ongoing management.^[2]

Several factors influence whether someone will recover well from a subdural haematoma. The size of the blood collection matters, as larger haematomas cause more pressure on brain tissue. Age plays a role, with older adults often facing more complications. The patient’s neurological condition when they arrive at the hospital is crucial. Those who can make conversation and have higher consciousness levels tend to fare better than those who are comatose. The presence of other medical conditions, particularly those affecting blood clotting, also influences recovery. Finally, how quickly treatment begins makes a significant difference, particularly for acute haematomas where rapid diagnosis and intervention save lives.^[8]

Even with the best medical care, subdural haematomas remain serious injuries. Without prompt treatment, large subdural haematomas can lead to death. Brain herniation, where pressure forces the brain from its normal position, represents a life-threatening complication. Patients may also experience repeated bleeding in the same location or complications from surgery itself. Long-term neurological deficits may persist despite successful treatment, requiring ongoing rehabilitation and support.^[7]

Survival Rate

Specific survival statistics vary depending on the type of subdural haematoma and associated factors. Acute subdural haematomas carry particularly high mortality rates due to the severity of the initial brain injury and rapid development of life-threatening pressure. Even with emergency surgery and intensive care, outcomes can be poor when extensive brain damage has occurred.^[8]

Research shows that presentation at the time of injury significantly affects survival. In large studies of patients with acute subdural haematomas requiring emergency neurosurgery, approximately half had moderate or mild head injuries initially, with Glasgow Coma Scale scores indicating they could converse before their condition worsened. These patients who receive timely medical and surgical intervention before further neurological deterioration have better chances of survival and recovery.^[8]

The interval between injury and treatment matters considerably. Some patients experience lucid intervals where they appear relatively well before symptoms worsen. In comprehensive literature reviews, lucid intervals occurred in up to 38 percent of acute subdural haematoma cases. People who receive treatment during this window, before severe deterioration occurs, have improved survival prospects compared to those who present already comatose.^[8]

For chronic subdural haematomas, survival rates are generally more favourable than for acute cases. However, even these less severe haematomas carry risks, particularly in elderly patients or those with multiple health problems. The overall prognosis depends heavily on timely diagnosis, appropriate treatment selection, and the patient’s ability to tolerate interventions such as surgery. While complete recovery may not always be possible, many patients can achieve meaningful improvement with proper care and rehabilitation support.^[2]

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