What causes dizziness that worsens when laying flat but improves when sitting?

Dizziness Worse When Lying Flat, Better When Sitting

This symptom pattern—dizziness that worsens when lying flat but improves with sitting—is the opposite of typical orthostatic symptoms and strongly suggests spontaneous intracranial hypotension (SIH), which requires urgent neurological evaluation and brain MRI. 1

Primary Diagnosis: Spontaneous Intracranial Hypotension

SIH should be your leading diagnosis when patients report worsening symptoms while lying flat with improvement upon sitting or standing. 1 This is the hallmark "orthostatic headache" pattern, though patients may describe it as dizziness rather than headache. 1

Key Diagnostic Features of SIH

The 2023 multidisciplinary consensus guideline from the Journal of Neurology, Neurosurgery and Psychiatry defines the classic presentation as: 1

• Symptoms are absent or mild (1-3/10 severity) on waking or after prolonged lying flat 1
• Symptom onset occurs within 2 hours of becoming upright 1
• After lying flat, symptoms improve by >50% within 2 hours 1
• The timing pattern is consistent across episodes 1

Some patients describe "end of the day" or "second half of the day" symptoms with improvement when lying flat, which represents the inverse of your patient's presentation but confirms the positional nature is key. 1

Associated Symptoms That Increase Suspicion

Look for accompanying features that strengthen the diagnosis of SIH: 1

• Neck pain or stiffness
• Hearing changes (muffled hearing, tinnitus)
• Visual disturbances
• Nausea
• Photophobia or phonophobia

Immediate Diagnostic Workup

Brain MRI with and without contrast is mandatory to evaluate for SIH. 1 Look for characteristic findings including pachymeningeal enhancement, subdural fluid collections, brain sagging, or venous engorgement. 1

Critical Differential Diagnoses to Exclude

Postural Orthostatic Tachycardia Syndrome (POTS)

POTS presents with severe orthostatic intolerance (light-headedness, palpitations, tremor, weakness, blurred vision, fatigue) primarily in young women. 1 The key distinguishing feature is a marked heart rate increase (>30 bpm, or >120 bpm within 10 minutes of standing) without significant blood pressure drop. 1

Perform orthostatic vital signs: Measure heart rate and blood pressure supine, then at 1,3,5, and 10 minutes of standing. 1 POTS shows dramatic tachycardia without the blood pressure drop seen in classic orthostatic hypotension. 1

Classical Orthostatic Hypotension

This diagnosis is unlikely given your patient's symptom pattern. 1 Classical orthostatic hypotension causes dizziness when standing that improves when lying down—the exact opposite of your patient's presentation. 1

If you suspect this despite the atypical presentation, document: 1

• Fall of >20 mmHg systolic and/or >10 mmHg diastolic blood pressure upon standing
• Symptoms of "coat hanger pain" (neck and shoulder pain), low back pain, or precordial pain
• Symptoms worse in morning, with heat exposure, after meals, or after exertion

Benign Paroxysmal Positional Vertigo (BPPV)

BPPV is characterized by brief episodes (10-60 seconds) of spinning vertigo triggered by specific head position changes, not by the act of lying flat versus sitting. 1, 2 The vertigo occurs with rolling over in bed, tilting the head back, or bending forward—not simply from being horizontal. 2

Perform the Dix-Hallpike maneuver to exclude BPPV. 1, 2 However, if you observe downbeat nystagmus (particularly without torsional component) or direction-changing nystagmus without position changes, this indicates central nervous system pathology requiring immediate MRI. 1, 3

Central Nervous System Pathology

Any patient with persistent dizziness when lying down requires urgent neurological evaluation to exclude posterior circulation stroke, cerebellar lesions, or brainstem pathology. 3

Red flags demanding emergency evaluation include: 1, 3

• Severe headache (especially thunderclap onset)
• Diplopia, dysarthria, dysphagia
• Ataxia or focal weakness
• Downbeat or direction-changing nystagmus
• Failure to respond to conservative management

Downbeat nystagmus specifically suggests cervicomedullary junction pathology. 3 Direction-changing nystagmus (beats right with right gaze, left with left gaze) or gaze-holding nystagmus indicates central rather than peripheral vestibular pathology. 1

Vestibular Migraine

Vestibular migraine causes episodic vestibular symptoms lasting 5 minutes to 72 hours, but these are spontaneous episodes, not consistently triggered by lying flat versus sitting. 1 Diagnosis requires ≥5 episodes with migraine features (migrainous headache, photophobia, phonophobia, or aura) during at least 50% of dizzy episodes. 1

Common Pitfalls to Avoid

1. Do not assume this is orthostatic hypotension based on the word "positional." The direction matters—worsening when lying flat is the opposite of orthostatic hypotension. 1

2. Do not perform only a Dix-Hallpike maneuver and stop there. While useful to exclude BPPV, abnormal nystagmus patterns (downbeat, direction-changing) mandate immediate brain imaging. 1, 3

3. Do not delay neuroimaging if red flag symptoms are present. Central causes like posterior circulation stroke can initially present with isolated dizziness in 10% of cases. 1

4. Do not miss SIH by focusing only on headache. Patients may describe their primary symptom as dizziness, lightheadedness, or imbalance rather than headache. 1

Predisposing Conditions to Assess

When SIH is suspected, inquire about: 1

• Connective tissue disorders (Ehlers-Danlos syndrome, Marfan syndrome)
• Joint hypermobility
• Recent spinal procedures or trauma (though SIH is often spontaneous)
• Spinal pathology (osteophytes, disc herniation)

Management Approach

If SIH is confirmed, initial conservative management includes bed rest, aggressive hydration, and caffeine. 1 Refractory cases may require epidural blood patch or surgical intervention, which should be coordinated with neurology and neurosurgery. 1

For orthostatic hypotension (if ultimately diagnosed despite atypical presentation), treatment includes alpha agonists like midodrine, mineralocorticoids, or lifestyle modifications. 4, 5 However, midodrine can cause marked supine hypertension (systolic pressures ~200 mmHg in 13.4% of patients on 10 mg), so supine and sitting blood pressures must be monitored closely. 4