What diagnostic tests are used to evaluate dizziness?

Diagnostic Approach to Dizziness

The diagnostic evaluation of dizziness should be guided by timing and triggers rather than symptom quality, with bedside physical examination tests being the primary diagnostic tools and imaging reserved for specific high-risk scenarios. 1, 2

Initial Clinical Classification

Categorize dizziness into one of four vestibular syndromes based on timing and triggers 1, 3, 2:

• Triggered Episodic Vestibular Syndrome (t-EVS): Brief episodes triggered by specific head movements 4, 5
• Spontaneous Episodic Vestibular Syndrome (s-EVS): Recurrent episodes without specific triggers 5
• Acute Vestibular Syndrome (AVS): Acute persistent dizziness lasting days to weeks 2, 5
• Chronic Vestibular Syndrome: Persistent symptoms over months 4

Essential Bedside Diagnostic Tests

For Triggered Episodic Vertigo

• Dix-Hallpike maneuver: Diagnoses posterior canal BPPV with 94% specificity when positive with vertigo or vomiting 1, 6
• Supine roll test: Evaluates horizontal canal BPPV 2, 7
• Key finding: Typical BPPV shows torsional, upbeating nystagmus 1

Critical caveat: Imaging is unnecessary for typical BPPV with positive Dix-Hallpike testing 4, 1. However, atypical features (lack of nystagmus on provoking maneuvers or lack of response to Epley maneuver) warrant MRI evaluation 4

For Acute Persistent Vertigo

• HINTS examination (Head-Impulse, Nystagmus, Test of Skew): Differentiates peripheral from central causes 1, 2, 7
• Observation for spontaneous nystagmus: Should be performed in all dizzy patients 2
• Complete neurologic examination: Identifies focal deficits suggesting central pathology 4, 2

For Presyncope/Disequilibrium

• Orthostatic blood pressure measurement: Essential for identifying orthostatic hypotension 8, 7, 9
• Cardiac examination: Evaluates for arrhythmias and structural heart disease 6, 8
• Romberg test: Low yield and should only be performed when specific findings are suspected 6

Imaging Indications

When Imaging is NOT Indicated

• Typical BPPV with positive Dix-Hallpike test and characteristic nystagmus 4, 1
• Acute persistent vertigo with normal neurologic examination and HINTS examination consistent with peripheral vertigo (vestibular neuritis) 4
• Nonspecific dizziness without vertigo, ataxia, or neurologic deficits due to low diagnostic yield (approximately 3-4%) 4

When MRI Head Without IV Contrast is Recommended

• Acute persistent vertigo with abnormal neurologic examination or HINTS examination suggesting central vertigo 4
• High vascular risk patients with acute persistent vertigo even with normal neurologic examination, as normal examination does not exclude posterior circulation infarct 4
• Chronic recurrent vertigo with brainstem neurologic deficits (vertebrobasilar insufficiency) 4
• Chronic disequilibrium with cerebellar ataxia signs 4

The diagnostic yield of MRI in isolated dizziness is only 4%, with ischemic stroke being the most common finding (70% of positive cases), and two-thirds located in the posterior circulation 4

When MRI Head and IAC Without and With IV Contrast is Indicated

• Chronic recurrent vertigo with unilateral hearing loss or tinnitus to exclude vestibular schwannoma or other structural causes 4

When CT Temporal Bone Without IV Contrast is Indicated

• Chronic recurrent vertigo with hearing loss to evaluate for superior semicircular canal dehiscence 4

When CT Head Without IV Contrast May Be Appropriate

• Initial imaging before MRI when central vertigo is suspected but MRI is not immediately available 4
• Note: CT is less sensitive than MRI for posterior circulation infarcts 4

When Vascular Imaging (MRA/CTA) is Indicated

• Chronic recurrent vertigo with brainstem deficits to evaluate vertebrobasilar circulation 4
• Disagreement exists on whether MRA/CTA should be initial imaging in acute central vertigo 4

Laboratory Testing

• Glucose testing: Should be performed routinely in all dizzy patients 6
• Cardiac rhythm monitoring: Indicated for patients age 45 and older 6
• Complete blood count, electrolytes, BUN: Low yield and should only be ordered based on specific clinical findings 6, 8

High-Risk Features Requiring Urgent Evaluation

Risk factors for serious causes (stroke, TIA) include 4, 6:

• Older age
• Hypertension
• Atrial fibrillation
• Non-whirling type of dizziness
• Combined neurological symptoms (headache, diplopia, dysarthria, numbness, weakness)
• Lack of vertigo in elderly patients

Common pitfall: Approximately 4% of isolated dizziness cases are due to stroke, and normal neurologic examination does not exclude posterior circulation infarct 4, 2. When a HINTS-trained practitioner is unavailable, maintain a lower threshold for MRI in high-risk patients 4.

Specific Syndrome Considerations

For Suspected Meniere Disease

Associated symptoms of hearing loss or tinnitus warrant MRI head and IAC with contrast to exclude vestibular schwannoma 4, 2

For Suspected Cerebellar Ataxia

MRI head without IV contrast or with contrast evaluates cerebellar atrophy or pathology 4. If spinal cord involvement is suspected, add MRI cervical and thoracic spine 4

For Suspected Sensory/Proprioceptive Ataxia

MRI cervical and thoracic spine without IV contrast (or with contrast) evaluates dorsal column pathology 4