What labs and tests are recommended for patients presenting with dizziness?

Diagnostic Approach to Patients Presenting with Dizziness

The most effective diagnostic approach for patients with dizziness should focus on timing and triggers of symptoms rather than symptom quality, with targeted laboratory and imaging tests based on specific clinical findings rather than routine comprehensive testing.

Initial Evaluation Framework

Categorizing Dizziness by Timing and Triggers

1. Acute Vestibular Syndrome (AVS) - Continuous dizziness lasting days

   • Perform HINTS examination (Head-Impulse, Nystagmus, Test of Skew) 1
   • Normal neurologic exam with HINTS consistent with peripheral vertigo suggests vestibular neuritis/labyrinthitis
   • Abnormal neurologic exam or HINTS suggesting central cause requires urgent MRI evaluation

2. Triggered Episodic Vestibular Syndrome - Brief episodes triggered by position changes

   • Perform Dix-Hallpike and supine roll tests 1
   • Positive tests with characteristic nystagmus suggest BPPV
   • Atypical features warrant further investigation

3. Spontaneous Episodic Vestibular Syndrome - Recurrent episodes without clear triggers

   • Evaluate for associated symptoms (hearing loss, tinnitus, headache)
   • Consider Menière's disease, vestibular migraine, or TIA

Key Physical Examination Components

• HINTS examination - 92.9% sensitivity, 83.4% specificity for central causes 2
• Dix-Hallpike maneuver - 94% specificity for peripheral vestibular disorders when positive 3
• Orthostatic vital signs - For presyncope evaluation 1
• Neurological examination - Focus on cerebellar testing and cranial nerves

Laboratory Testing

Targeted laboratory testing is appropriate based on clinical suspicion, but routine comprehensive testing is not useful 1.

• Blood glucose - Recommended for all patients with dizziness 3
• Targeted blood tests - Reasonable in selected patients based on history, physical exam, and ECG 1
• Brain natriuretic peptide and troponin - Consider only when cardiac cause is suspected 1

Imaging Studies

Routine imaging is not recommended for uncomplicated dizziness with normal neurological examination 1.

Indications for imaging:

• Abnormal neurological examination
• HINTS examination suggesting central cause
• New headache or neck pain
• Risk factors for cerebrovascular disease with acute persistent vertigo

When imaging is indicated:

• MRI head without contrast - First-line for suspected central causes 1
• CT head without contrast - Less sensitive but may be appropriate as initial imaging when MRI is not immediately available 1

Common Pitfalls to Avoid

1. Relying solely on symptom quality descriptions (vertigo vs. lightheadedness) rather than timing and triggers
2. Ordering routine comprehensive laboratory testing for all dizzy patients
3. Overuse of neuroimaging in patients with clear peripheral causes
4. Failure to perform the HINTS examination in acute vestibular syndrome
5. Missing posterior circulation strokes by relying on normal CT findings (MRI with DWI is more sensitive)

Special Considerations

• Elderly patients - Higher risk for serious causes; lower threshold for imaging
• Medication review - Essential in all dizzy patients
• Cardiac monitoring - Consider in patients ≥45 years old 3
• Vestibular testing (VNG, caloric testing) - Not recommended for routine diagnosis of Ménière's disease 1

The diagnostic approach to dizziness has evolved from the traditional symptom-quality paradigm to a timing-and-triggers approach, which has been shown to more effectively differentiate between benign and serious causes while reducing unnecessary testing 4, 5.