What are the key features in the history and examination that help differentiate between primary and secondary headaches?

Key features in history and examination that differentiate primary from secondary headaches include:

• Onset and progression: Primary headaches (such as migraine, tension-type, and cluster headaches) typically have a gradual onset and characteristic patterns, whereas secondary headaches often have a sudden onset, especially if reaching maximum intensity within 5 minutes (thunderclap headache), which is a red flag for serious causes like subarachnoid haemorrhage ¹,².
• Associated symptoms: Primary headaches may have typical associated symptoms such as aura in migraine (fully reversible neurological symptoms developing over 5 to 60 minutes), photophobia, nausea, or autonomic features in cluster headache (e.g., red watery eye, nasal congestion) ¹. Secondary headaches may present with systemic symptoms like fever, neck stiffness, altered consciousness, or new neurological deficits ¹,².
• Neurological examination: Normal neurological examination is typical in primary headaches, while new-onset neurological deficits, cognitive dysfunction, or personality changes suggest secondary causes ¹.
• Triggers and exacerbating factors: Secondary headaches may be triggered by cough, Valsalva manoeuvre, exercise, or posture changes (orthostatic headache), which are uncommon in primary headaches ¹.
• History of trauma or systemic illness: Recent head trauma, compromised immunity, or history of malignancy raise suspicion for secondary headaches ¹.
• Headache characteristics: Primary headaches have characteristic pain locations and qualities (e.g., bilateral pressing pain in tension-type headache, unilateral pulsating pain in migraine, unilateral severe pain around the eye in cluster headache) ¹. Secondary headaches often have atypical or changing headache patterns ¹.

Summary: A careful history focusing on headache onset, associated symptoms, triggers, systemic features, and neurological examination findings helps differentiate primary headaches from secondary headaches that require urgent investigation or referral ¹,².