From the Guidelines
A head CT should not be routinely repeated after a normal result, unless there are new or worsening neurological symptoms, as the risk of delayed intracranial hemorrhage is low, even in patients on anticoagulants or antiplatelet agents, as shown in a recent study 1. The decision to repeat a head CT scan after a normal result should be based on the clinical context and the reason for the initial scan.
- If a head CT was normal and symptoms have resolved, there is no need for routine follow-up imaging.
- However, for patients with ongoing neurological symptoms, new symptoms, or specific conditions requiring monitoring, repeat imaging may be warranted. Some studies suggest 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, as the risk of delayed intracranial hemorrhage is low, and even if it does occur, it tends not to be clinically significant and rarely necessitates neurosurgical intervention 1. For example, in cases of mild traumatic brain injury with initial normal imaging but persistent symptoms, a repeat CT might be considered after 24-48 hours, as suggested by some guidelines 1. The timing of repeat imaging should be individualized based on the patient's specific condition, symptom progression, and risk factors, rather than following a standardized schedule when the initial scan was normal. It is also important to consider the radiation exposure risks associated with repeat head CT scans, as each scan delivers approximately 2 mSv of radiation. Clear discharge instructions with return precautions are warranted, especially for patients on anticoagulants or antiplatelet agents, due to the potential for delayed intracranial hemorrhage, although the risk is low 1.
From the Research
Repeat Head CT Scans
- The frequency of repeat head CT scans depends on various factors, including the severity of the traumatic brain injury and the patient's clinical condition 2, 3.
- Patients with severe head injury (Glasgow Coma Scale (GCS) score < or = 8) may benefit from routine repeat head CT scans, as results may lead to intervention without neurologic change 2.
- For patients with mild to moderate head injury, the role of routine repeat head CT scans is controversial, and the decision to repeat the scan should be based on clinical judgment and individual patient factors 3, 4.
Clinical Indicators for Repeat Head CT Scans
- Clinical indicators for repeat head CT scans include neurologic deterioration, loss of consciousness, amnesia, seizures, cephalgia, somnolence, dizziness, nausea, and clinical signs of fracture 2, 3, 4.
- A GCS score of <15, abnormal international normalized ratio (INR), midline shift, effaced basal cisterns, and multiple hemorrhagic lesions are also associated with worsening of repeat CT, neurological deterioration, and/or need for neurosurgical intervention 3.
Imaging Modalities
- Computed tomography (CT) is the modality of choice for initial assessment of traumatic brain injury, but magnetic resonance imaging (MRI) may provide more clinically relevant information, especially in cases of abusive head trauma 5, 6.
- Diffusion tensor imaging (DTI) is a newer modality that may be useful for assessing traumatic axonal injury and prognostic decision making, but requires further validation 6.