What are the main differences between Idiopathic Intracranial Hypertension without Papilledema (IIHwop) and Vestibular Migraine in terms of diagnosis and treatment?

Distinguishing IIHwop from Vestibular Migraine

IIHwop and vestibular migraine are distinct conditions that share overlapping symptoms—particularly headache, dizziness, and pulsatile tinnitus—but differ fundamentally in pathophysiology: IIHwop requires documented elevated intracranial pressure (≥20 cm H₂O on lumbar puncture) without papilledema, while vestibular migraine is diagnosed clinically by ≥5 episodes of vestibular symptoms lasting 5 minutes to 72 hours with migraine features, and does not require elevated opening pressure. 1, 2

Key Diagnostic Differences

IIHwop Diagnostic Criteria

• Requires elevated CSF opening pressure ≥20 cm H₂O on lumbar puncture performed on at least two occasions, without papilledema present 1, 3
• Strong association with obesity (average BMI 37.4 in one series), predominantly affects women 1, 4
• Pulsatile tinnitus is highly predictive (odds ratio 13.0 for IIHwop versus other causes of chronic daily headache) 3
• Neuroimaging may reveal transverse sinus stenosis, sigmoid sinus dehiscence, empty sella, or tonsillar ectopia 4
• Headache is typically progressively more severe and frequent, often chronic daily headache 1, 3

Vestibular Migraine Diagnostic Criteria

• Requires ≥5 episodes of vestibular symptoms (spontaneous vertigo, positional vertigo, visually induced vertigo, or head-motion intolerance) lasting 5 minutes to 72 hours 2, 5
• Must have current or history of migraine with or without aura 2, 5
• At least 50% of episodes must have migraine features: moderate-to-severe headache with unilateral location, pulsating quality, photophobia, phonophobia, or visual aura 2, 5
• Normal CSF opening pressure when lumbar puncture is performed 2, 5
• Lifetime prevalence 3.2%, accounting for up to 14% of vertigo cases 2, 6

Clinical Overlap and Diagnostic Challenges

Shared Symptoms

Both conditions commonly present with:

• Headache (93.5% in IIHwop series) 7
• Dizziness (77.4% in IIHwop patients) 4, 7
• Pulsatile tinnitus (67.7% in IIHwop) 4, 7
• Aural fullness (61.3% in IIHwop) 7

Critical Distinguishing Features

• Episodic true vertigo occurs in only 22.6% of IIHwop patients versus being a defining feature (≥5 episodes required) in vestibular migraine 4, 7
• Pulsatile tinnitus is far more characteristic of IIHwop (odds ratio 13.0) and relates to transverse sinus stenosis, whereas it is less prominent in vestibular migraine 4, 3
• Obesity strongly predicts IIHwop (odds ratio 4.4) but is not a defining feature of vestibular migraine 3
• CSF opening pressure is the definitive discriminator: elevated in IIHwop, normal in vestibular migraine 1, 2, 3

Important Caveat

Recent evidence suggests IIHwop may actually present as vestibular migraine in some patients, with raised intracranial pressure causing endolymphatic hydrops and vestibular symptoms that improve after lumbar puncture and CSF pressure normalization 4, 7. This indicates that lumbar puncture with opening pressure measurement is essential when obesity, pulsatile tinnitus, and vestibular symptoms coexist, even if the clinical picture initially suggests vestibular migraine 4, 7.

Treatment Differences

IIHwop Treatment Priorities

The three main treatment principles are: (1) treat the underlying disease, (2) protect vision, and (3) minimize headache morbidity 1

• Carbonic anhydrase inhibitors (acetazolamide) are first-line pharmacological treatment to reduce CSF production 4
• Weight loss is critical given the strong obesity association 1
• Serial lumbar punctures may provide temporary relief and confirm diagnosis 4, 7
• Dural venous sinus stenting for refractory cases with documented transverse sinus stenosis 4
• Migraine prophylaxis may be added to manage headache symptoms 1

Vestibular Migraine Treatment Priorities

Acute Management:

• Vestibular suppressants (diphenhydramine, meclizine) for acute attacks only, not long-term use 2
• Triptans for concurrent headache 2, 5
• Antiemetics to ameliorate symptoms 2

Preventive Treatment (when symptoms occur ≥2 days/month):

• First-line: Beta blockers (propranolol, metoprolol, atenolol), topiramate 50-100 mg daily, or candesartan 2
• Second-line: Flunarizine, amitriptyline/nortriptyline (especially with comorbid anxiety/depression), or valproic acid (men only) 2
• Third-line: CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab) for refractory cases 2
• Assess efficacy after 2-3 months at therapeutic dose; consider pausing after 6-12 months of successful control 2

Lifestyle Modifications (first-line for both conditions):

• Regular sleep schedule, stress reduction, dietary modifications (limit salt, caffeine, alcohol), regular exercise, adequate hydration 2

Diagnostic Algorithm

When evaluating a patient with headache, dizziness, and possible vestibular symptoms:

1. Assess for red flags suggesting IIHwop: obesity (BMI >30), pulsatile tinnitus (especially if dural sinus quality), chronic progressive headache, transient visual obscurations 1, 4, 3

2. If red flags present: Obtain neuroimaging (MRI/MRV to evaluate for transverse sinus stenosis, empty sella, tonsillar ectopia) and perform lumbar puncture with opening pressure measurement 1, 4

3. If opening pressure ≥20 cm H₂O without papilledema: Diagnose IIHwop and initiate carbonic anhydrase inhibitors plus weight loss 1, 4

4. If opening pressure normal and patient has ≥5 episodes of vestibular symptoms (5 min-72 hours) with migraine features: Diagnose vestibular migraine and initiate lifestyle modifications plus preventive therapy if symptoms ≥2 days/month 2, 5

5. Critical pitfall: Do not assume vestibular migraine in obese patients with pulsatile tinnitus without measuring opening pressure, as IIHwop can mimic vestibular migraine and requires different treatment 4, 7, 3