What are the initial laboratory tests and diagnostic evaluations for a patient presenting with dizziness (vertigo)?

From the Guidelines

Initial laboratory tests and diagnostic evaluations for dizziness should include complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid function tests, and electrocardiogram (ECG), as well as audiometry testing when hearing loss is present, to help identify common causes of dizziness and differentiate between peripheral vestibular disorders, central nervous system disorders, cardiovascular issues, and metabolic causes. These basic tests help identify common causes of dizziness such as anemia, electrolyte abnormalities, thyroid dysfunction, and cardiac arrhythmias. Additional targeted testing should include orthostatic vital signs, measuring blood pressure and heart rate while lying down and then standing, to assess for orthostatic hypotension. Depending on the clinical presentation, vestibular function tests like the Dix-Hallpike maneuver may be appropriate to evaluate for benign paroxysmal positional vertigo (BPPV) 1. For patients with neurological symptoms, brain imaging with MRI should be considered to rule out central causes, as recommended by the clinical practice guideline for Meniere's disease 1. Audiometry testing is valuable when hearing loss accompanies dizziness, suggesting potential Meniere's disease or acoustic neuroma, and clinicians should obtain an audiogram when assessing a patient for the diagnosis of Meniere's disease 1. Blood glucose testing is important, especially in diabetic patients, as hypoglycemia can cause dizziness. These tests provide a comprehensive initial evaluation that helps differentiate between peripheral vestibular disorders, central nervous system disorders, cardiovascular issues, and metabolic causes of dizziness, allowing for appropriate treatment planning based on the underlying etiology. It is also important to note that clinicians should not routinely order vestibular function testing or electrocochleography to establish the diagnosis of Meniere's disease, as stated in the clinical practice guideline for Meniere's disease 1. Instead, the diagnosis of Meniere's disease remains a clinical diagnosis based on patient-reported symptomatology and audiometric data 1. By following this approach, clinicians can provide a thorough and effective evaluation for patients presenting with dizziness, prioritizing morbidity, mortality, and quality of life as the outcome. Key points to consider in the diagnostic evaluation of dizziness include:

• Complete blood count (CBC)
• Comprehensive metabolic panel (CMP)
• Thyroid function tests
• Electrocardiogram (ECG)
• Orthostatic vital signs
• Audiometry testing when hearing loss is present
• Dix-Hallpike maneuver for benign paroxysmal positional vertigo (BPPV)
• Brain imaging with MRI for patients with neurological symptoms
• Blood glucose testing, especially in diabetic patients.

From the Research

Initial Laboratory Tests and Diagnostic Evaluations

The initial laboratory tests and diagnostic evaluations for a patient presenting with dizziness (vertigo) involve a thorough patient history and physical examination.

• The patient's history is crucial in determining the cause of dizziness, with a focus on the timing and triggers of the events 2, 3, 4, 5, 6.
• The physical examination includes orthostatic blood pressure measurement, a full cardiac and neurologic examination, assessment for nystagmus, and the Dix-Hallpike maneuver 4, 5, 6.
• The HINTS (head-impulse, nystagmus, test of skew) examination can help distinguish peripheral from central etiologies 4, 5.

Diagnostic Approach

A new diagnostic approach to the adult patient with acute dizziness emphasizes different aspects of the history to guide a focused physical examination, with the goal of differentiating benign peripheral vestibular conditions from dangerous posterior circulation strokes 6.

• This approach divides patients into three key categories using timing and triggers:
  • Acute vestibular syndrome, where bedside physical examination differentiates vestibular neuritis from stroke.
  • Spontaneous episodic vestibular syndrome, where associated symptoms help differentiate vestibular migraine from transient ischemic attack.
  • Triggered episodic vestibular syndrome, where the Dix-Hallpike and supine roll test help differentiate benign paroxysmal positional vertigo from posterior fossa structural lesions 6.

Laboratory Testing and Imaging

Laboratory testing and imaging are usually not required and are usually not helpful in the initial evaluation of dizziness 4.

• However, they can be helpful in certain cases, such as when central etiologies are suspected or when the diagnosis is unclear 5.