What is the initial approach to a headache workup?

Initial Approach to Headache Workup

Begin with a focused medical history applying ICHD-3 criteria and a complete neurological examination to identify red flags that distinguish secondary from primary headache disorders, reserving neuroimaging only for patients with abnormal neurological findings or specific warning features. 1, 2

Step 1: Obtain Targeted History

The diagnostic evaluation centers on specific headache characteristics that differentiate primary from secondary causes:

• Temporal features: Document age at onset, duration of individual episodes (migraine: 4-72 hours; cluster: 15-180 minutes; tension-type: variable), frequency of attacks, and pattern of progression 1, 3
• Pain characteristics: Assess location (unilateral vs bilateral), quality (pulsating vs pressing/tightening), and intensity (mild-moderate vs severe-very severe) 1
• Associated symptoms: Screen for nausea/vomiting, photophobia, phonophobia (migraine features), or ipsilateral autonomic symptoms like lacrimation, conjunctival injection, nasal congestion (cluster headache features) 1, 4
• Aura symptoms: Identify visual distortions, scotomas, or hemisensory disturbances that precede headache onset 1, 3
• Medication history: Document all acute medication use, specifically frequency per month, as regular overuse (≥15 days/month for non-opioid analgesics or ≥10 days/month for other acute medications) for >3 months indicates medication-overuse headache 1, 2
• Trigger factors: Identify dietary triggers (alcohol, caffeine, tyramine, nitrates), environmental factors (stress, perfumes, flickering lights), hormonal changes, or missed meals 1, 3

Step 2: Screen for Red Flags Requiring Urgent Investigation

Red flags in the history mandate immediate consideration of secondary headache disorders:

• Thunderclap headache (sudden onset, "worst headache ever") suggests subarachnoid hemorrhage 1, 5
• New-onset headache in patients ≥50 years raises concern for temporal arteritis or mass lesion 1, 3
• Progressively worsening headache or rapidly increasing frequency suggests evolving pathology 1, 2
• Headache awakening patient from sleep or worsened by Valsalva maneuver increases likelihood of intracranial pathology 1, 4
• Atypical aura (prolonged, motor symptoms) or recent head trauma 1, 3
• Associated symptoms: Fever, impaired memory, syncope, or focal neurological symptoms 1, 2

Step 3: Perform Complete Neurological Examination

A systematic neurological assessment is mandatory to identify abnormalities that significantly increase the likelihood of intracranial pathology:

• Mental status examination 2
• Cranial nerve testing (including assessment for nystagmus, which increases suspicion for posterior fossa lesions) 2
• Motor and sensory function (focal deficits mandate imaging) 2
• Reflexes (abnormal reflexes significantly increase likelihood of significant pathology) 2
• Coordination and gait testing 2

An abnormal neurological examination is a Grade B indication for neuroimaging. 1, 3

Step 4: Determine Need for Neuroimaging

Neuroimaging should be avoided unless it will change management and is indicated only when secondary headache is suspected based on red flags or abnormal examination. 1

Indications for neuroimaging (MRI preferred over CT):

• Unexplained abnormal neurological examination findings (Grade B recommendation) 1, 3
• Any red flag features including headache worsened by Valsalva, awakening from sleep, new-onset in older patients, or progressive worsening 1, 4
• Atypical headache features that do not fulfill standard migraine criteria (Grade C recommendation) 1, 3
• Suspected cerebral venous thrombosis in patients with progressive headache and dizziness 2

When neuroimaging is NOT indicated:

• Migraine with normal neurological examination (Grade B recommendation against routine imaging, as prevalence of significant abnormality is only 0.2%) 1, 3
• Tension-type headache with normal examination 1

Imaging modality selection:

• MRI is preferred when imaging is needed, as it offers higher resolution without ionizing radiation 1
• CT is acceptable for acute evaluation, though MRI and CT appear similarly sensitive for clinically significant pathology 1
• Be aware: MRI may reveal clinically insignificant abnormalities (white matter lesions, arachnoid cysts, meningiomas) that can alarm patients and lead to unnecessary further testing 1

Step 5: Consider Additional Testing When Indicated

Beyond neuroimaging, specific clinical scenarios require additional workup:

• Lumbar puncture: Indicated for suspected subarachnoid hemorrhage with negative CT, suspected meningitis/encephalitis, or suspected intracranial hypotension/high-pressure syndromes 2
• Blood work: Consider when fever present or systemic illness suspected 1

Step 6: Classify the Headache Disorder

Once secondary causes are excluded, differentiate primary headache disorders:

Migraine (affects 12% of population):

• Unilateral, pulsating, moderate-to-severe pain lasting 4-72 hours 2
• Aggravated by routine physical activity 1
• Accompanied by nausea/vomiting and/or photophobia and phonophobia 1, 2
• May have aura (visual, sensory) 3

Tension-type headache (affects 38% of population):

• Bilateral, mild-to-moderate, pressing/tightening quality 1
• NOT aggravated by routine physical activity 1
• Lacks migraine-associated symptoms 1

Cluster headache (affects ~0.1% of population):

• Strictly unilateral, severe-to-very severe intensity 1
• Short duration (15-180 minutes) 1, 4
• Frequency of 1-8 attacks per day 4
• Ipsilateral autonomic symptoms (lacrimation, conjunctival injection, nasal congestion) 1, 4

Medication-overuse headache:

• Headache ≥15 days/month with regular acute medication overuse >3 months 2
• Often develops from treating migraine attacks, leading to conflation of the two disorders 1
• Critical pitfall: Only 20% of patients meeting criteria for chronic migraine are properly diagnosed, often because medication-overuse headache is overlooked 2

Common Pitfalls to Avoid

• Over-imaging: Neuroimaging in migraine patients with normal examinations exposes patients to unnecessary radiation, cost, and anxiety from incidental findings 1
• Missing medication-overuse headache: Always quantify monthly medication use, as this secondary headache mimics chronic migraine and requires different management 2
• Ignoring patient reassurance needs: While excessive worry alone may justify imaging in select cases (Grade C consideration), education about the low probability of serious pathology (0.2% in migraine with normal exam) is often more appropriate 1
• Failing to consider cerebral venous thrombosis: This can present with non-specific progressive headache and dizziness, particularly when precipitated by conditions like spontaneous intracranial hypotension 2