What is the likely diagnosis and treatment for a 27-year-old patient with chronic lightheadedness (dizziness) that worsens with movement and improves in the evening, accompanied by a feeling of blockage and clicking in the left ear, with normal ear exam, heart sounds, and head examination, and has shown mild improvement with betahistine (histamine receptor agonist) and the Epley maneuver?

Likely Diagnosis: Ménière's Disease vs. Vestibular Migraine

Based on the chronic nature of lightheadedness lasting hours with left ear fullness and clicking, plus partial response to betahistine, this presentation most strongly suggests Ménière's disease, though vestibular migraine remains an important differential. 1

Key Diagnostic Features Supporting Ménière's Disease

The combination of symptoms points toward Ménière's disease:

• Episodic dizziness lasting hours (not seconds like BPPV) with spontaneous onset fits the spontaneous episodic vestibular syndrome pattern 1
• Unilateral ear fullness and clicking are classic features of Ménière's disease, representing fluctuating endolymphatic pressure 1, 2
• Partial response to betahistine is consistent with Ménière's disease, as betahistine improves inner ear blood flow and is specifically used for this condition 3, 4, 5
• Mild response to Epley maneuver suggests this is NOT pure BPPV, as BPPV should have 80% success with Epley 6

Critical Next Steps for Diagnosis

Obtain a comprehensive audiologic examination immediately to document low-to-mid frequency sensorineural hearing loss, which is the key distinguishing feature of Ménière's disease 1. The presence of fluctuating hearing loss definitively separates Ménière's disease from vestibular migraine, which has stable or absent hearing loss 2.

Essential History to Clarify

• Assess for migraine features: current or past migraine history, family history of migraine, photophobia, phonophobia, or visual aura during at least 50% of vertigo episodes 2
• Characterize the hearing symptoms: Is there fluctuating hearing loss that worsens over time? Tinnitus? 1, 2
• Duration of individual episodes: Ménière's typically causes sustained attacks lasting hours, while vestibular migraine can range from 5 minutes to 72 hours 2

Why This is NOT Typical BPPV

The Epley maneuver should achieve 80-98% success for true BPPV 6, yet symptoms persist. Key features arguing against BPPV:

• Episodes last hours, not seconds (BPPV episodes last <1 minute) 1, 7
• Constant symptoms that "come back" rather than brief positional episodes 1
• Ear fullness and clicking are NOT features of BPPV 1
• Only mild improvement with Epley suggests either wrong diagnosis or concurrent pathology 6

Recommended Treatment Algorithm

If Ménière's Disease is Confirmed (with documented hearing loss):

1. Dietary sodium restriction (1500-2000 mg/day) 1, 2
2. Diuretics (typically hydrochlorothiazide or acetazolamide) 1, 2
3. Continue betahistine (current dose appears subtherapeutic; standard is 48 mg/day divided in 3 doses) 3, 5
4. Vestibular rehabilitation therapy for residual symptoms 1

If Vestibular Migraine is Suspected (no hearing loss):

1. Migraine prophylaxis (topiramate, propranolol, or amitriptyline) 1, 2
2. Lifestyle modifications: identify and avoid triggers (motion, light sensitivity) 1, 2
3. Dietary modifications: consider migraine diet restrictions 2

Important: 35% of Ménière's patients also meet criteria for vestibular migraine 1, so both conditions may coexist.

Red Flags Requiring Urgent Neuroimaging

Order MRI brain without contrast immediately if any of these are present 1, 2:

• Focal neurological deficits on examination
• Sudden unilateral hearing loss (this is an emergency) 1
• New severe headache accompanying dizziness
• Inability to stand or walk
• Downbeating or central nystagmus patterns
• Failure to respond to appropriate vestibular treatments after 1 month

Common Pitfalls to Avoid

• Assuming normal ear exam excludes inner ear pathology: Ménière's disease typically has a normal otoscopic examination 1
• Overlooking vestibular migraine in a 27-year-old, as it accounts for 14% of all vertigo cases and is extremely common in young patients 1, 2
• Continuing Epley maneuvers indefinitely when the diagnosis is likely NOT BPPV 6
• Using betahistine at subtherapeutic doses: standard dosing is 16 mg three times daily (48 mg/day total) 3, 5

Why Betahistine Helps (Partially)

Betahistine improves outcomes in both BPPV and Ménière's disease by:

• Improving inner ear blood flow 5
• Inducing production of CTRP family proteins that activate ERK1/2-AKT/PPARγ pathways 4
• Reducing residual dizziness, particularly with 4 weeks of treatment 3

However, betahistine alone is insufficient treatment—the underlying diagnosis must be confirmed and specific therapy initiated 1, 5.