What are the causes and treatments of sudden onset dizziness?

Sudden Onset Dizziness: Causes and Treatment

The most critical first step is determining the timing pattern—brief episodes (seconds to minutes) suggest benign paroxysmal positional vertigo (BPPV), while acute persistent vertigo (hours to days) requires urgent evaluation to distinguish peripheral vestibular disorders from life-threatening posterior circulation stroke. 1

Classification by Timing (Most Important Diagnostic Feature)

The timing and triggers of dizziness are far more diagnostically valuable than the patient's subjective description of "spinning" versus "lightheadedness." 1, 2

Brief Episodic Vertigo (Seconds to Minutes)

• BPPV is the most common cause when vertigo lasts <1 minute and is triggered by specific head movements 1, 3
• Episodes are provoked by rolling over in bed, looking up, or bending forward 4
• The Dix-Hallpike maneuver is the gold standard diagnostic test, showing 5-20 second latency, torsional upbeating nystagmus toward the affected ear, and resolution within 60 seconds 1, 4

Acute Persistent Vertigo (Hours to Days)

• Vestibular neuritis causes severe rotational vertigo lasting 12-36 hours with nausea and vomiting, but without hearing loss, tinnitus, or aural fullness 4
• Posterior circulation stroke must be urgently excluded—approximately 25% of patients with acute vestibular syndrome have cerebrovascular disease, rising to 75% in high vascular risk patients 5
• Critical pitfall: 75-80% of posterior circulation stroke patients have no focal neurologic deficits on standard examination 5, 1

Spontaneous Episodic Vertigo (Minutes to Hours)

• Ménière's disease presents with episodes lasting 20 minutes to 12 hours, accompanied by fluctuating hearing loss, tinnitus, and aural fullness 4
• Vestibular migraine requires ≥5 episodes lasting 5 minutes to 72 hours with migraine features (headache, photophobia, phonophobia, or visual aura) during at least 50% of episodes 4, 1

Physical Examination Priorities

For Brief Episodic Symptoms

• Perform the Dix-Hallpike maneuver immediately—no imaging or laboratory testing is indicated for typical BPPV presentations 1, 4
• Assess for modifying factors including impaired mobility, CNS disorders, lack of home support, and fall risk 4

For Acute Persistent Symptoms

• The HINTS examination (Head Impulse, Nystagmus, Test of Skew) has 100% sensitivity for detecting posterior circulation stroke when performed by trained practitioners, compared to only 46% for early MRI 1, 5
• However, HINTS is unreliable when performed by non-experts 1
• Check orthostatic blood pressure to evaluate for presyncope 3, 2

Red Flags Requiring Urgent Evaluation

These findings mandate immediate imaging (MRI brain without contrast preferred) and neurologic consultation: 1, 5

• Focal neurological deficits (dysarthria, dysmetria, dysphagia, sensory/motor loss, Horner's syndrome) 4
• Sudden hearing loss 1
• Inability to stand or walk independently 1, 5
• New severe headache 1
• Downbeating nystagmus or direction-changing nystagmus without head position changes 4
• High vascular risk factors (age >65, hypertension, diabetes, prior stroke) with acute vestibular syndrome 1, 5

Imaging Decisions

When Imaging is NOT Indicated

• Typical BPPV with positive Dix-Hallpike test and no additional concerning features 1
• Acute persistent vertigo with normal neurologic exam AND HINTS examination consistent with peripheral vertigo by a trained examiner 1

When MRI is Required

• Abnormal neurologic examination 1
• HINTS examination suggesting central cause 1
• High vascular risk patients with acute vestibular syndrome 1, 5
• Unilateral or pulsatile tinnitus 1
• Asymmetric hearing loss 1

Critical Imaging Pitfall

• CT head has only 20-40% sensitivity for posterior circulation infarcts and should not be used instead of MRI when stroke is suspected 1
• CT diagnostic yield is <1% for isolated dizziness 1

Treatment by Diagnosis

BPPV (First-Line Treatment)

• Canalith repositioning procedures (Epley maneuver) achieve 80% success after 1-3 treatments and 90-98% after repeat maneuvers 1, 3
• No medications are needed for typical BPPV 1, 6
• Reassess within one month to document resolution or persistence 1

Vestibular Neuritis

• Steroids may be beneficial in the acute phase 3
• Vestibular rehabilitation therapy is the primary intervention for persistent symptoms, significantly improving gait stability compared to medication alone 1

Ménière's Disease

• Salt restriction and diuretics are first-line management 1
• Intratympanic dexamethasone or gentamicin for refractory cases 3

Vestibular Migraine

• Migraine prophylaxis and lifestyle modifications 1
• Avoid vestibular suppressants, which impair central compensation 2

Medication-Induced Dizziness

• Review antihypertensives, sedatives, anticonvulsants, and psychotropic drugs—this is a leading reversible cause of chronic dizziness 1

Role of Vestibular Suppressants

• Meclizine is FDA-approved for vertigo associated with vestibular system diseases 6
• However, pharmacologic intervention is limited because it often impairs the central nervous system's ability to compensate for dizziness 2
• Vestibular suppressants should be used sparingly and only in the acute phase 2

Common Diagnostic Pitfalls to Avoid

• Do not rely on patient descriptions of "spinning" versus "lightheadedness"—focus on timing and triggers instead 1, 2
• Do not assume normal neurologic exam excludes stroke—most posterior circulation strokes present without focal deficits 1, 5
• Do not order routine imaging for straightforward BPPV—it delays treatment and has extremely low diagnostic yield 1
• Do not use CT when stroke is suspected—it misses most posterior circulation infarcts 1
• Do not fail to perform positional testing (Dix-Hallpike) in patients with brief episodic symptoms 1