Dangerous Causes of Dizziness

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Dizziness is a very common problem. Fortunately, most of the time symptoms of dizziness are caused by a problem that isn’t life threatening, and is often reversible or will resolve or improve on its own. Sometimes, though, dizziness is a sign that something much more serious is going on.

Vertebrobasilar Insufficiency

The most immediately dangerous thing that can cause dizziness is a stroke that causes central vertigo, meaning a problem in the brainstem or brain rather than the inner ear or vestibular nerve.

The brainstem receives its blood supply from the vertebral arteries, which merge together to form the basilar artery. Reduced blood supply through these blood vessels is jointly referred to as vertebrobasilar insufficiency.

If blood supply is reduced for a brief period of time, it can cause a transient ischemic attack. If the flow of oxygen is stopped long enough for permanent damage to occur, it causes a stroke. Strokes in the brainstem are extremely dangerous since in addition to balance the brainstem also controls breathing and other functions vital to life.

To learn more about vertebral basilar insufficiency and central vertigo, read here:

Vertebral Basilar Insufficiency

Brainstem Infection

The most common infection that leads to vertigo is a viral labyrinthitis, meaning a virus that leads to inflammation in the inner ear. This isn't usually life-threatening. But a virus isn’t the only thing that can cause such inflammation.

Other, more severe diseases can inflame the inner ear or even the brainstem. Examples include fungi such as Cryptococcus or bacteria such as tuberculosis or listeria. Furthermore, some viruses like herpes zoster or varicella zoster can cause inflammation in the ear that could be part of a wider and more dangerous infectious process.

Heart Disease

In contrast to those disorders which cause an illusory sense of motion (vertigo), many other disorders can cause lightheadedness, the sense that one may pass out. Most of us have felt this when standing up too quickly, especially when hungry or dehydrated. This occurs when too little blood reaches the brain. Sometimes loss of consciousness (syncope) can result.

Most of the time causes of lightheadedness amount to little more than dehydration. The most serious causes, though, include heart diseases that stop the heart from efficiently pumping blood against gravity’s pull. Cardiac arrhythmias can come and go, creating episodes of lightheadedness. Other heart diseases such as infarctions, tumors, and more may also need to be considered.

For this reason, if someone is starting to feel lightheaded for no apparent reason, it is recommended that they get a good medical evaluation.

Endocrine Tumors

While it is very rare, some tumors secrete hormones that end up making us feel dizzy. An example is an insulinoma, a tumor that secretes the same hormone taken by some diabetics to keep their blood sugar low. In the setting of this tumor, the blood sugar can become too low, resulting in sensations of dizziness, weakness and more.

A pheochromocytoma secretes hormones that can increase blood pressure or make someone feel very anxious, which may sometimes be interpreted as dizziness.

Miller-Fisher variant of Guillain-Barré Syndrome

Guillain-Barré is an autoimmune disorder that attacks the peripheral nervous system. This causes weakness and sensory changes. Usually, this starts at the tips of the toes and fingers and moves inwards and upwards along the body. In the Miller-Fisher variant, though, the eyes and face are affected first, and the patient becomes ataxic meaning a clumsiness especially when walking. The combination of ataxia and visual changes can be interpreted as dizziness.

Wernicke’s Encephalopathy

Wernicke’s encephalopathy is caused by a deficiency of the vitamin thiamine. Like the Miller-Fischer variant of Guillain-Barré syndrome, people with Wernicke’s encephalopathy can have problems moving their eyes and difficulty walking. Furthermore, they can develop memory problems which may become irreversible unless they are given the vitamin as soon as possible. For this reason, Wernicke’s encephalopathy is considered a medical emergency.

Medication Toxicity

Several medications can cause sensations of almost every type of dizziness. The variations are too numerous to be explored here. For more information, visit : Is My Dizziness a Side Effect?

While these possibilities are frightening, they are also thankfully much less frequently encountered than more common causes of dizziness. To learn more about these causes, read (link).


Newman-Toker, DE, Symptoms and Signs of Neuro-otologic Disorders, Continuum Lifelong Learning Neurol 2012;18(5):1016–1040.

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