Vertigo refers to a sensation of spinning, swaying, or feeling off-balance. It is a symptom, not a disease, indicating an underlying issue. This disorienting feeling can range from mild and brief episodes to severe and prolonged experiences, significantly impacting daily activities.
Understanding Vertigo’s Causes
Vertigo can originate from problems in two primary areas: the peripheral vestibular system or the central nervous system.
The peripheral vestibular system includes the inner ear and its connecting nerves, responsible for balance and spatial orientation. Common peripheral causes include Benign Paroxysmal Positional Vertigo (BPPV), characterized by brief vertigo spells triggered by head movements.
Meniere’s disease, involving fluid buildup in the inner ear, also causes peripheral vertigo, leading to hearing loss and ringing. Another peripheral cause is vestibular neuritis, an inflammation of the vestibular nerve, often following a viral infection, causing sudden and severe vertigo.
Central vertigo arises from issues within the brain or brainstem, which process balance signals. These causes, such as stroke, brain tumors, or multiple sclerosis, affect the brain’s ability to interpret balance information and are often more serious. Recognizing the origin of vertigo, whether peripheral or central, guides the diagnostic approach.
How MRI Helps Diagnose Vertigo
Magnetic Resonance Imaging (MRI) uses strong magnetic fields and radio waves to create detailed images of organs and soft tissues. For vertigo, an MRI does not detect the sensation itself, but identifies structural abnormalities in the brain or inner ear that could be causing the symptom. It can reveal brain tumors pressing on balance pathways or lesions characteristic of multiple sclerosis affecting central nervous system function.
The imaging technique also detects signs of stroke, especially in the brainstem or cerebellum, areas important for balance coordination. An MRI can also visualize structural issues within the inner ear, such as an acoustic neuroma, a benign tumor on the nerve connecting the ear to the brain. In some specific cases, it can also show signs of fluid imbalances in the inner ear, though this is not always definitively diagnostic for conditions like Meniere’s disease.
However, an MRI cannot detect the most common peripheral causes of vertigo. Conditions like Benign Paroxysmal Positional Vertigo (BPPV), Meniere’s disease, or vestibular neuritis are functional disorders, involving a disruption in the balance system rather than a visible structural change. BPPV, for instance, is caused by dislodged calcium carbonate crystals too small for MRI detection. Thus, a normal MRI scan indicates the absence of structural problems, but does not rule out vertigo.
When an MRI is Recommended
A doctor recommends an MRI for vertigo when “red flag” symptoms suggest a possible central cause. These warning signs indicate a serious issue within the brain or brainstem. Such symptoms include new, severe, or persistent vertigo accompanied by neurological deficits like double vision, weakness, numbness, or difficulty speaking or swallowing. In these cases, an MRI is often warranted.
Other concerning symptoms prompting an MRI referral include an unusual severe headache, loss of consciousness, or significant imbalance affecting walking. An MRI might also be considered if initial assessments, including physical maneuvers and patient history, do not suggest common peripheral causes or if vertigo exhibits atypical characteristics. This diagnostic step helps rule out or confirm conditions requiring immediate or specialized treatment.
Complementary Diagnostic Methods
Since MRI primarily identifies structural issues, other diagnostic tools are used to pinpoint vertigo’s cause, especially for suspected peripheral causes. A thorough physical and neurological exam is often the first step, where a doctor assesses balance, coordination, eye movements, and reflexes. Specific positional tests, like the Dix-Hallpike maneuver, can help diagnose conditions such as Benign Paroxysmal Positional Vertigo (BPPV) by observing characteristic eye movements (nystagmus) triggered by head positions.
Specialized balance tests evaluate vestibular system function. These include:
Videonystagmography (VNG) or electronystagmography (ENG) record eye movements to evaluate the function of the vestibular system.
Caloric testing, a component of VNG/ENG, involves introducing warm and cool water or air into the ear canal to stimulate the inner ear, helping to assess the responsiveness of each balance organ.
Additionally, audiometry (hearing tests) can detect hearing loss, which is a symptom often associated with inner ear conditions like Meniere’s disease.
In some cases, blood tests may be performed to check for underlying medical conditions or infections that could contribute to vertigo.