Adults and children with headache: evidence-based diagnostic evaluation.

Headache represents one of the most common complaints in the outpatient and emergency room setting [1]. Most causes of headache are benign and do not require emergent imaging or intervention. The authors' review of the diagnostic tests does not offer absolute indications for neuroimaging because most of the evidence is based on studies that are not randomized controlled trials. Imaging guidelines for adults and children, however, have emerged based on the available level 2 and 3 literature. CT imaging remains the initial test of choice for new-onset headache in adults and headache suggestive of SAH. Most of the available literature also recommends performing lumbar puncture when CT is equivocal in ruling out SAH [1]. The sensitivity of MR imaging appears to be less than CT for SAH [1]. Newer MR imaging techniques need to be tested and developed to determine if they have higher sensitivity than CT or lumbar puncture in the detection of SAH. In adults with suspected brain metastatic disease, contrast-enhanced MR imaging is the imaging study of choice [38,39]. Contrast-enhanced MR imaging is the examination of choice for brain metastatic lesions less than 2 cm [39]. CT angiography and MR angiography have sensitivities greater than 85% for brain aneurysms larger than 5 mm [43]. If clinically warranted, aneurysms smaller than 5 mm may require digitally subtracted angiography because of the low sensitivity of MR and CT angiography. In children, the choice of diagnostic test strategy depends on the risk group. In high-risk patients, MR imaging is the test of choice whereas in low-risk patients, close clinical observation with periodic reassessment is the best strategy [44]. Clinical diagnosis will always play a key role in the evaluation of headache disorders; however, for the small subset of patients who present with headache secondary to an intracranial space-occupying lesion, bleeding, or SAH, making the diagnosis is crucial to decreasing morbidity and mortality. CT, MR imaging, and lumbar puncture play important roles in the assessment of headache disorders, but their future roles will continue to evolve as the technology becomes more sophisticated and robust, and physicians become more expert with their use [1].