When Two Neurologists Find No Signs on Examination
If two neurologists find no abnormalities on neurological examination, neuroimaging is generally not warranted in patients with nonacute headache, as the absence of abnormal neurological findings significantly decreases the likelihood of clinically significant intracranial pathology. 1
Evidence-Based Rationale
Impact of Normal Neurological Examination
The absence of abnormalities on neurological examination substantially decreases the likelihood of detecting significant lesions on CT or MRI imaging studies. 1
In patients with nonacute headache and normal neurological examinations, the prevalence of significant intracranial abnormalities is approximately 0.2%—no greater than the rate found in completely asymptomatic individuals undergoing brain MRI. 1, 2
The American Academy of Family Physicians explicitly recommends that neuroimaging (either MRI or CT) is not usually warranted in patients with migraine who have normal findings on neurological examination (Grade B recommendation). 2
When to Reconsider Despite Normal Examination
While a normal neurological examination is reassuring, certain historical features may still warrant imaging consideration, though the evidence remains insufficient for definitive recommendations: 1
- Rapidly increasing frequency of headaches 1
- Headache awakening the patient from sleep 1, 2
- Headache worsened by Valsalva maneuver 1, 2
- History of dizziness or lack of coordination 1
- History of numbness or tingling 1
- New-onset headache in older patients 2
- Patient's report of "worst headache in my life" 1
However, the absence of these clinical features does not reduce the odds of an abnormality on neuroimaging, creating a clinical dilemma. 1
Guiding Principles for Decision-Making
The U.S. Headache Consortium advocates three consensus-based principles: 1
Testing should be avoided if it will not lead to a change in management 1, 2
Testing is not recommended if the patient is not significantly more likely than the general population to have a significant abnormality 1, 2
Testing that is not normally recommended may make sense in individual cases, such as in patients who are excessively worried about a serious problem as the cause of their headaches 1
Common Pitfalls to Avoid
Do not assume that concerning historical features automatically override a normal neurological examination by two specialists. The examination findings carry substantial weight in risk stratification. 1
Avoid ordering neuroimaging purely for patient reassurance without considering the risks of false-positive findings. False positive results are much more likely than true positive ones when the pre-test probability is low, potentially leading to unnecessary concerns, further investigation, and procedures. 1
Be aware that most studies informing these guidelines were conducted at referral centers, which may overestimate the prevalence of significant abnormalities in primary care populations. 1
Clinical Context Matters
For patients with migraine and normal neurological examination: neuroimaging is not usually warranted. 2
For patients with tension-type headache and normal neurological examination: while official guidelines state insufficient data, the available evidence from chronic headache studies provides reassurance that imaging is almost always unnecessary. 1
The reliability of neurological examination varies by clinical context. In comatose patients, the neurological examination has limited diagnostic reliability (74% sensitive, 60% specific for acute brain damage), but in alert patients with headache, the examination is more reliable. 3