What is the initial workup for a patient presenting with dizziness?

Initial Workup for Dizziness

The initial workup for dizziness should focus on classifying the type of dizziness based on timing and triggers, followed by targeted physical examination including HINTS testing for acute vestibular syndrome, with MRI brain being the preferred imaging modality when central causes are suspected. 1, 2

Classification of Dizziness

Dizziness can be categorized into three main patterns based on timing and triggers:

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

   • Key causes: Vestibular neuritis, stroke (25% of AVS cases) 1
   • Examination: HINTS examination (Head-Impulse, Nystagmus, Test-of-Skew)
   • Red flag: Abnormal HINTS suggests central cause requiring urgent evaluation

2. Episodic Vestibular Syndrome:

   • Spontaneous: Recurrent episodes without clear trigger
     • Key causes: Vestibular migraine, TIA, Menière's disease
   • Triggered: Episodes provoked by specific movements
     • Key cause: Benign Paroxysmal Positional Vertigo (BPPV)
     • Examination: Dix-Hallpike maneuver

3. Chronic Vestibular Syndrome: Persistent dizziness lasting months

   • Often related to compensation issues or multiple factors

Physical Examination Components

• Vital signs: Including orthostatic blood pressure measurements
• Neurological examination: Cranial nerves, coordination, gait, strength
• Vestibular examination:
  • Nystagmus assessment (direction, trigger factors)
  • HINTS examination for AVS (more sensitive than CT for posterior circulation stroke) 1
  • Dix-Hallpike maneuver for suspected BPPV
• Cardiovascular examination: Heart rate, rhythm, murmurs

Diagnostic Testing

• Imaging:

  • MRI brain: Preferred for suspected central vertigo (higher sensitivity than CT) 2
    • Indicated for: Abnormal HINTS exam, neurological deficits, high vascular risk patients with AVS, chronic undiagnosed dizziness not responding to treatment 2
  • CT head: Low sensitivity (~10%) for posterior fossa strokes but useful to exclude hemorrhage in emergency settings 1

• Laboratory tests (selective use based on history):

  • Complete blood count
  • Electrolytes, glucose
  • Thyroid function tests
  • Vitamin B12 levels (if peripheral neuropathy suspected)

Red Flags Requiring Urgent Evaluation

• Sudden severe headache with dizziness
• New neurological symptoms
• Inability to walk or stand
• Persistent vomiting with dizziness
• Altered mental status 2

Common Pitfalls to Avoid

1. Relying solely on symptom quality descriptions (vertigo, lightheadedness) rather than timing and triggers to guide diagnosis
2. Missing posterior circulation strokes by not performing HINTS examination in acute vestibular syndrome
3. Overreliance on CT imaging which has poor sensitivity for posterior fossa strokes
4. Excessive use of vestibular suppressant medications like meclizine, which can delay central compensation 3
5. Failure to consider medication side effects as potential causes of dizziness

Medication Considerations

• Review current medications that may contribute to dizziness:

  • Sedatives
  • Antihypertensives
  • Muscle relaxants
  • Anticonvulsants

• Meclizine: FDA-indicated for vertigo associated with vestibular system diseases

  • Dosage: 25-100 mg daily in divided doses
  • Caution: Causes drowsiness; avoid alcohol and operating machinery
  • Not recommended for long-term use as it may delay central compensation 3

Remember that approximately 20% of dizziness cases may not receive a definitive diagnosis despite thorough evaluation 4. Focus on excluding dangerous causes first, then manage symptoms appropriately based on the most likely etiology.