Which of the following is a clinical red flag for secondary headaches?

A progression or fundamental change in headache pattern is a significant clinical red flag for secondary headaches. This type of change can indicate an underlying medical condition that may require further investigation. For example, if a patient who previously had episodic tension-type or migraine headaches experiences a marked increase in frequency, severity, or a transformation to a chronic headache pattern, it could be a sign of a more serious issue such as a mass lesion, hemorrhage, or other structural abnormalities in the brain.

Other manifestations and characteristics of headaches can provide important context but do not carry the same level of concern as a change in pattern. For instance, headaches that improve with rest are often associated with primary headache disorders like tension-type headaches or migraines. Headaches occurring only during sleep may indicate benign night-time headaches, rather than a serious underlying condition. Similarly, headaches that are exclusively unilateral (one-sided) can be characteristic of migraine or cluster headaches but do not inherently suggest a secondary cause unless accompanied by other concerning symptoms.

In summary, a fundamental change in headache pattern is particularly alarming for clinicians as it can point to potentially serious underlying conditions that may require immediate evaluation and intervention.