What diagnostic tests can be ordered for a patient presenting with dizziness or lightheadedness?

Diagnostic Tests for Dizziness and Lightheadedness

The most effective diagnostic approach for dizziness or lightheadedness begins with categorizing the symptom into one of four types (vertigo, presyncope, disequilibrium, or lightheadedness), followed by targeted testing based on this classification.

Initial Classification of Dizziness

First, determine which type of dizziness the patient is experiencing:

1. Vertigo: Sensation of spinning or movement
2. Presyncope: Feeling of impending faint
3. Disequilibrium: Unsteadiness when walking
4. Lightheadedness: Vague sensation of disconnection

Key Diagnostic Tests by Category

For Vertigo Symptoms

• HINTS examination - More sensitive than early MRI (100% vs 46%) for detecting stroke 1

  • Head Impulse Test
  • Nystagmus Evaluation
  • Test of Skew

• Dix-Hallpike maneuver - Gold standard for diagnosing posterior canal BPPV 1

  • Positive test shows torsional, upbeating nystagmus

• Supine roll test - For lateral semicircular canal BPPV when Dix-Hallpike is negative 1

• Audiogram - Essential for evaluating hearing loss associated with Ménière's disease 2

• Video- or electronystagmogram - Evaluates vestibular function of the ear 2

• Electrocochleography - Measures electrical responses of the cochlea and auditory nerve 2

For Presyncope/Orthostatic Symptoms

• 3-minute active stand test - Measure blood pressure and heart rate lying down and standing 2

  • For suspected postural tachycardia syndrome, extend to 10 minutes

• Tilt table testing - For delayed orthostatic hypotension or reflex syncope 2

• ECG - To evaluate for cardiac causes of presyncope

• Blood tests - Complete blood count, kidney and liver function, electrolytes 2

For Disequilibrium

• Validated assessment tools 1:
  • Activities-Specific Balance Confidence Scale
  • Dynamic Gait Index
  • Timed Up & Go test

For Lightheadedness or Mixed Symptoms

• Blood tests 2:
  • Full blood count
  • Kidney and liver function
  • C-reactive protein
  • Ferritin
  • B-type natriuretic peptide
  • Thyroid function

Imaging Studies

• MRI brain (without contrast) - Indicated for 1:

  • Acute Vestibular Syndrome with abnormal HINTS examination
  • Any neurological deficits
  • High vascular risk patients with acute vestibular syndrome
  • Chronic undiagnosed dizziness not responding to treatment

• CT temporal bone - For assessing bony abnormalities in peripheral vertigo 1

• MRA Head and Neck - To detect vascular stenosis when vertebrobasilar insufficiency is suspected 1

Red Flags Requiring Urgent Evaluation

• Sudden severe headache
• New neurological symptoms
• Inability to walk or stand
• Persistent vomiting
• Altered mental status 1

Diagnostic Algorithm

1. Determine timing pattern:

   • Acute (continuous for days)
   • Episodic (seconds to hours)
   • Chronic (weeks to months)

2. For acute vestibular syndrome: Perform HINTS examination

   • If abnormal → MRI brain
   • If normal → Treat as peripheral vestibulopathy

3. For episodic vertigo:

   • If positionally triggered → Dix-Hallpike and supine roll tests
   • If spontaneous → Evaluate for Ménière's disease or vestibular migraine

4. For presyncope:

   • Perform orthostatic vital signs
   • Review medications
   • Consider cardiac evaluation

5. For disequilibrium:

   • Assess for neurological conditions (Parkinson's, neuropathy)
   • Evaluate gait and balance

Remember that laboratory testing and radiography play a limited role in most cases of dizziness 3, and a final diagnosis is not obtained in approximately 20% of cases. The most effective approach is systematic categorization followed by targeted physical examination tests.