From the Guidelines
Brain MRI is not justified in young patients with only syncope, as the diagnostic yield is extremely low and it is not recommended in the routine evaluation of patients with syncope in the absence of focal neurological findings or head injury. Syncope, or fainting, is typically caused by temporary reductions in blood flow to the brain due to vasovagal reactions, orthostatic hypotension, or cardiac arrhythmias rather than structural brain abnormalities. According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1, MRI and CT of the head are not recommended in the routine evaluation of patients with syncope, as brain structural abnormalities are rare and these imaging modalities are frequently used but infrequently helpful.
The guideline states that in 5 studies investigating patients with syncope, MRI was used in 11% of 397 patients and established a diagnosis in only 0.24% 1. Similarly, in 10 studies of investigation of syncope, CT was used in 57% of 2728 patients and established a diagnosis in only 1% 1. This suggests that the use of brain MRI in young patients with only syncope would not be diagnostically useful and would likely result in unnecessary cost and resource utilization.
Instead, the initial evaluation should focus on a thorough history, physical examination, orthostatic vital signs, and an ECG. Additional cardiac testing may be warranted depending on the clinical presentation. Brain imaging should be reserved for patients with syncope who have accompanying neurological symptoms, abnormal neurological examination findings, history of head trauma, or when the history suggests a neurological cause rather than typical syncope. This approach aligns with the principle of appropriate resource utilization while ensuring that patients receive diagnostically useful evaluations based on their specific clinical presentation.
Key points to consider in the evaluation of patients with syncope include:
- A thorough history and physical examination to identify potential causes of syncope
- Orthostatic vital signs to assess for orthostatic hypotension
- An ECG to evaluate for cardiac arrhythmias
- Additional cardiac testing as warranted by the clinical presentation
- Brain imaging only in patients with accompanying neurological symptoms, abnormal neurological examination findings, history of head trauma, or when the history suggests a neurological cause rather than typical syncope.
From the Research
Evaluation of Syncope in Young Patients
- Syncope is a common condition in children and adolescents, characterized by a sudden, self-limited loss of consciousness and postural tone, followed by spontaneous and complete recovery 2.
- The primary classifications of syncope are cardiac, reflex (neurogenic), and orthostatic, with the immediate cause being cerebral hypoperfusion due to systemic vasodilation, decreased cardiac output, or both 3.
Diagnostic Approach
- Evaluation of syncope focuses on history, physical examination, and electrocardiographic results, with additional testing considered if findings are inconclusive or indicate possible adverse outcomes 3.
- Neuroimaging, such as brain MRI, should be ordered only when findings suggest a neurologic event or a head injury is suspected 3.
- In the case of young patients with only syncope, the diagnosis is primarily clinical, and objective laboratory investigations add little to the diagnosis, especially in the neurocardiogenic subtype 2.
Justification for Brain MRI
- There is no clear justification for performing a brain MRI in young patients with only syncope, unless there are specific findings that suggest a neurologic event or head injury 3.
- The existing evidence suggests that the prognosis for neurocardiogenic syncope is excellent, and the condition can be managed with behavior and lifestyle modifications, followed by drugs in refractory cases 2.
- The use of brain MRI in this population would likely be low-yield and may not provide additional diagnostic information, unless there are specific clinical indications 3, 4.