What is the time course and number of computed tomography (CT) scans for asymptomatic acute subdural hematoma (SDH)?

From the Guidelines

For asymptomatic acute subdural hematomas (SDH) in patients on anticoagulants or antiplatelet agents, a single CT scan at diagnosis is likely sufficient, with no routine need for repeat imaging, as the risk of delayed ICH is low, approximately 1-5%. This recommendation is based on the most recent and highest quality study available, which suggests that delayed ICH after blunt head trauma in neurologically intact patients on anticoagulant or antiplatelet therapy is rare, and even if it does occur, it tends not to be clinically significant and rarely necessitates neurosurgical intervention 1.

Some key points to consider in the management of these patients include:

• The risk of spontaneous ICH in association with anticoagulation is well described, but the incidence of delayed ICH after a negative initial head CT scan is very low, approximately 1-5% 1.
• Most studies support the notion that patients on anticoagulants, or antiplatelet agents, with a normal initial head CT after blunt trauma and who are neurologically intact can be safely discharged 1.
• Clear discharge instructions with return precautions are warranted, as some patients may develop delayed ICH, although this is rare 1.
• The decision to withhold anticoagulant or antiplatelet medication after the injury should be made on a case-by-case basis, weighing the risk of repeat trauma or lack of good social support for home observation against the risk of delayed ICH 1.

It's also important to note that the American College of Radiology (ACR) Appropriateness Criteria for head trauma suggest that routine repeat CT in the presence of a normal initial CT and in the absence of neurologic deterioration is not necessary 2. However, the most recent and highest quality study available suggests that a single CT scan at diagnosis is likely sufficient for asymptomatic acute subdural hematomas (SDH) in patients on anticoagulants or antiplatelet agents 1.

In terms of the number of CT scans needed, typically, only 1 CT scan is required, as the risk of delayed ICH is low, and most patients can be safely discharged after a normal initial head CT scan 1. However, individual patient factors, such as age, anticoagulation status, and size of the hematoma, may necessitate more frequent imaging or a longer period of observation.

From the Research

Time Course and Number of CT Scans for Asymptomatic Acute Subdural Hematoma (SDH)

• The time course and number of computed tomography (CT) scans for asymptomatic acute subdural hematoma (SDH) are not directly addressed in the provided studies 3, 4, 5, 6, 7.
• However, a study on asymptomatic chronic subdural hematoma found that only one patient required neurosurgical intervention at 3 months from the time of initial presentation after the development of symptoms 5.
• The same study reported that medical teams performed follow-up imaging for 57 patients (53.8%) culminating in a total of 116 follow-up scans, predominantly for falls or monitoring purposes 5.
• Another study on acute subdural hematoma in the elderly found that patients with a Glasgow Coma Scale (GCS) score of 13-15 can be observed clinically, and the expected outcome is very good 6.
• A systematic review and meta-analysis of outcomes following surgery for acute subdural haematoma in the elderly found that pooled estimates of mortality were 39.83% at discharge and 49.30% at long-term follow-up 7.

CT Scan Factors Influencing Surgical Treatment Decision

• A study on acute subdural hematoma in the elderly found that CT factors such as SDH-thickness, midline shift, and intracranial pressure (ICP) can influence the surgical treatment decision 6.
• The study reported that patients with a midline shift >10 mm and SDH thickness > midline shift may require surgery, while those with a midline shift > SDH thickness and ICP > 40 mmHg may not benefit from surgery 6.
• Another study found that increased maximal hematoma thickness, low hemoglobin level, and high leukocyte count were independent risk factors for delayed surgical intervention in patients with acute traumatic subdural hematoma 4.