“Red Flags” in the Diagnostic Process
Most headaches are primary and do not indicate the presence of underlying diseases. There are cases, however, in which head pain is a symptom of a life-threatening disorder. The physician must recognize red flags that indicate the presence of such serious conditions as they require immediate treatment. Potential seriousness indications include recent, particularly intense and very sudden headaches; pain that either are new after the age of 50 or have substantially changed from the previous head pain patterns; headaches that are concomitant with neurological deficits; headache with papilledema, loss of consciousness, seizures or cognitive impairments, meningeal irritation, or other abnormal neurological signs. Neuroimaging is the most important investigation in headache practice, followed by CSF and blood examinations. Imaging must be performed when red flags are present, and further tests such as spinal taps are required when neuroimaging is not elucidative. Venous thrombosis and the reversible cerebral vasoconstriction syndrome are examples of overlooked disorders that frequently present with headache only and require magnetic resonance venography (MRV) and arteriography for a proper diagnosis. Subarachnoid hemorrhage secondary to intracranial aneurysm, cerebral venous thrombosis, idiopathic thunderclap headache, meningitis, reversible cerebral vasoconstriction syndrome, posterior reversible encephalopathy syndrome, acute sinus disease, pituitary apoplexy, primary intracranial hypotension, hydrocephalus, and intracranial occupying lesions are all diseases that may present with headache as the most important or unique symptom.