Headache - Clinical Evaluation and Investigation

Headache Diagnosis and Evaluation Introduction Most headaches are diagnosed through clinical history alone—neuroimaging and advanced testing are reserved for specific situations. The key to effective headache evaluation is identifying whether you're dealing with a primary headache disorder (migraine, tension-type, or cluster headache) or a secondary headache caused by an underlying condition. This distinction determines whether you need additional testing and how urgently you need it. Assessing Old vs. New Headaches The first critical step is determining whether you're dealing with an old or new headache pattern. An old headache has an established, longstanding pattern that the patient has experienced before. These are typically primary headaches and usually don't require urgent neuroimaging if they follow the patient's typical pattern. A new headache is either completely new onset or represents a change in an existing headache pattern. These require more careful evaluation because a change in established patterns can signal an underlying problem. Why this matters for exams: Questions often ask whether a patient needs imaging. A key principle is that established, unchanged headache patterns in patients with normal exams typically don't need imaging, while new or changed headaches do. POUND Mnemonic: Distinguishing Migraine from Tension-Type Headache The POUND mnemonic helps you differentiate migraine from tension-type headache based on clinical features: Pulsatile quality: A throbbing or beating sensation (vs. tension-type, which is typically pressing/tightening) One-day duration: Lasts 4–72 hours (tension-type is typically 30 minutes to several hours) Unilateral location: One-sided (tension-type is usually bilateral/diffuse) Nausea/vomiting: Associated with nausea or vomiting (tension-type rarely has this) Disabling intensity: Severe enough to prevent normal activities (tension-type is mild-to-moderate) Meeting 4 or more POUND criteria strongly suggests migraine. This distinction matters because it guides both diagnosis and treatment—migraines are treated with triptans and preventive agents, while tension-type headaches are treated with simple analgesics. Key point: A patient reporting a pulsatile, one-sided headache with nausea lasting 6 hours that forces them to leave work meets POUND criteria and should be diagnosed as migraine. SSNOOP: Red-Flag Warning Signs The SSNOOP mnemonic identifies "red-flag" features that mandate urgent evaluation and neuroimaging. When you encounter any of these features, assume secondary pathology until proven otherwise. Systemic symptoms: Fever, weight loss, night sweats, or signs of systemic illness Systemic disease: Known cancer, HIV, immunosuppression, or other systemic conditions that increase risk of intracranial pathology Neurologic signs: Focal deficits (weakness, numbness, coordination problems), papilledema, cognitive changes, or abnormal neurological exam Onset sudden: "Thunderclap" onset—reaches maximum intensity within seconds to minutes (classic for subarachnoid hemorrhage) Onset after age 50: New headache in a patient over 50 years old (increased risk of structural disease, giant cell arteritis, etc.) Previous headache history: This is first headache ever, worst headache of life, or distinctly different from prior headaches Why this matters: Any single SSNOOP feature warrants urgent neuroimaging. For example, a patient with sudden-onset "worst headache of life" needs immediate CT imaging to rule out subarachnoid hemorrhage—don't wait. Clinical History and Physical Examination Essential History Elements Diagnosis of primary headaches relies on carefully obtained history that characterizes: Onset pattern: Gradual vs. sudden Duration: How long does each episode last? Frequency: How often does it occur? Location: Unilateral, bilateral, localized, or diffuse? Quality: Throbbing, pressing, sharp, dull? Associated symptoms: Nausea, vomiting, photophobia, phonophobia, visual disturbances Triggers: Foods, stress, sleep, hormonal cycles, weather Impact: How much does it interfere with daily activities? Physical Examination Findings The neurological examination should specifically assess for: Papilledema: Suggests increased intracranial pressure Focal neurological deficits: Weakness, sensory loss, coordination problems, or speech abnormalities Meningeal signs: Neck stiffness or positive Kernig sign (suggests meningitis) Fever: Combined with headache, suggests infection Cranial nerve abnormalities: Particularly important in cluster headache (Horner syndrome) or other secondary causes A normal neurological examination in a patient with typical primary headache features significantly lowers the probability of serious pathology. Neuroimaging: When and How Indications for Neuroimaging Order urgent neuroimaging in the following situations: Any red-flag feature from SSNOOP New headache after age 50 Significant change in headache pattern Abnormal neurological examination findings Suspected subarachnoid hemorrhage, meningitis, or other acute intracranial process Do NOT routinely image: Patients with established primary headaches (old pattern), normal neurological exams, and no red flags do not need imaging. Unnecessary imaging increases cost and anxiety without improving outcomes. Choosing the Right Imaging Modality Non-contrast CT scan is first-line for acute headache because it: Rapidly detects acute bleeding (subarachnoid hemorrhage, epidural hematoma) Is widely available and quick Is appropriate when you're evaluating sudden severe headache MRI is preferred when you need to evaluate: Brain tumors and structural lesions Posterior fossa abnormalities Subtle intracranial pathology (demyelinating disease, ischemia) Chronic headache with red flags but negative CT Practical point for exams: If a question asks about sudden worst headache of life, answer CT. If it asks about evaluating a patient with progressive headache and papilledema, answer MRI. Lumbar Puncture Lumbar puncture (spinal tap) is performed to analyze cerebrospinal fluid (CSF) in specific situations: After a negative CT scan when subarachnoid hemorrhage is still suspected: CT can miss small subarachnoid hemorrhages, particularly in the first 6 hours. If clinical suspicion remains high and CT is negative, LP with CSF analysis (looking for xanthochromia) is essential. When meningitis is suspected: CSF analysis shows elevated protein, low glucose, and white cell count. In idiopathic intracranial hypertension: LP measures opening pressure and provides diagnostic confirmation. Important safety point: Never perform LP if there are signs of increased intracranial pressure without first ruling out mass effect with neuroimaging, as it can precipitate brain herniation. Summary: Diagnostic Approach The efficient approach to headache diagnosis follows this logic: Take detailed history → Characterize the headache pattern Check for SSNOOP red flags → Determines urgency and need for imaging Perform neurological exam → Look for deficits, papilledema, or signs of infection Order imaging if indicated → CT for acute/sudden onset, MRI for chronic with red flags Consider LP → When imaging is negative but clinical suspicion remains high for serious pathology This approach avoids unnecessary testing while ensuring dangerous conditions aren't missed.