Why does a 30-year-old female patient with intractable migraine experience worsening symptoms when in a supine position?

Worsening Migraine When Lying Flat: Differential Diagnosis and Clinical Approach

When a migraine worsens in the supine position rather than improving, you must immediately consider spontaneous intracranial hypotension (SIH) as the primary alternative diagnosis, not typical migraine. 1

Key Diagnostic Distinction

Typical Migraine Pattern

• Migraine headache characteristically worsens with increased intracranial pressure (Valsalva maneuver, coughing, bending forward) and is aggravated by movement rather than posture 1, 2
• Migraine pain typically does not improve when lying flat; if anything, cerebral venous congestion in the supine position can intensify migraine pain in 68% of patients 3
• The headache is provoked by movement (walking, climbing stairs), not by postural changes 1

Spontaneous Intracranial Hypotension (SIH) Pattern

• Orthostatic headache is the hallmark: absent or mild (1-3/10) on waking or after prolonged lying flat 1
• Headache onset occurs within 2 hours of becoming upright 1
• After lying flat, headache shows >50% improvement in severity within 2 hours 1
• The timing of onset and offset with position changes is consistent 1
• May present as "end of the day" or "second half of the day" headache with improvement when lying flat 1

Critical Clinical Features to Assess

History Elements That Point to SIH

• Temporal pattern: Does the headache truly improve (>50% reduction) within 2 hours of lying flat? 1
• Morning pattern: Is the headache absent or minimal upon waking? 1
• Consistency: Does this positional relationship occur reliably with each attack? 1
• Associated symptoms: Neck stiffness, tinnitus, hearing changes, nausea, photophobia (all can occur in SIH) 1
• Predisposing factors: History of connective tissue disorders (including Marfan's syndrome), joint hypermobility, or spinal pathology 1, 4

Red Flags Requiring Urgent Evaluation

• New daily persistent headache with initial orthostatic quality 1
• Thunderclap headache followed by orthostatic headache 1
• Headache that awakens the patient from sleep 1
• Progressive worsening pattern 1
• Any neurologic deficits on examination 1

Diagnostic Workup

When to Suspect SIH Over Migraine

If the patient reports genuine improvement when lying flat (not just lack of movement-related aggravation), proceed with:

1. Neuroimaging: Brain MRI with gadolinium to look for pachymeningeal enhancement, subdural fluid collections, brain sagging, or venous distension 1

2. Spinal imaging: MRI of entire spine to identify CSF leak, meningeal diverticula, or spinal pathology 1, 4

3. CSF pressure measurement: Lumbar puncture showing opening pressure <60 mm H₂O supports SIH 5

4. Specialized studies: Radioisotope cisternography or CT myelography if leak location needs identification 1, 4

Referral Pathway

• Urgent neurology referral (48 hours) if patient cannot care for themselves but has help 1
• Emergency admission if patient cannot care for themselves and lacks support 1
• Specialist neuroscience center referral (within 1 month) if diagnosis uncertain or first-line treatments fail 1

Alternative Diagnoses to Consider

Other Causes of Positional Headache

• Postural tachycardia syndrome (PoTS): Diagnosed by heart rate increase >30 bpm on standing test 1
• Orthostatic hypotension: Fall of >20 mmHg systolic and/or >10 mmHg diastolic BP on standing 1
• Cervicogenic headache: Provoked by cervical movement (not posture), reduced cervical range of motion, myofascial tenderness 1

Vestibular Migraine Consideration

• If vertigo or dizziness accompanies the headache, vestibular migraine requires ≥5 episodes of moderate-to-severe vestibular symptoms lasting 5 minutes to 72 hours 6, 7
• Visual auras are more common in vestibular migraine 7
• However, vestibular migraine is still provoked by movement rather than posture 1

Common Pitfalls to Avoid

1. Assuming all headaches in migraine patients are migraine: A patient with established migraine can develop SIH, particularly if they have connective tissue disorders 1, 4

2. Misinterpreting "worse when upright" as movement sensitivity: True orthostatic headache improves dramatically (>50%) when lying flat, which is distinctly different from migraine's movement sensitivity 1

3. Delaying imaging in atypical presentations: When the positional pattern doesn't fit typical migraine (improvement with lying flat), neuroimaging should not be deferred 1

4. Missing medication overuse headache: Frequent use of triptans (≥10 days/month), ergotamine, opiates, or analgesics (≥15 days/month) for ≥3 months can cause daily headaches that may have atypical features 1

Management Implications

If this is true migraine (worsens with movement, not improved by lying flat):

• The supine position may actually worsen pain due to cerebral venous congestion 3
• Standard migraine acute treatment with triptans, NSAIDs, or antiemetics applies 1
• Consider preventive therapy if attacks occur >2 times per week 1

If this is SIH (improves >50% when lying flat):

• Initial conservative management: bed rest, hydration, caffeine 5
• Epidural blood patch is highly effective for positional headaches from CSF leak 1, 4
• Avoid standard migraine preventives until SIH is treated 1