Dizziness (Dizzy) (cont.)
Vasovagal syncope
Vasovagal syncope is a common cause of dizziness, lightheadedness, and fainting. The vagus nerve is overstimulated and causes the body's blood vessels to dilate and the heart to slow down. This anti-adrenaline effect decreases the ability of the heart to pump blood upward to the brain. Without blood flow, the brain turns off. In Victorian England, when this happened because young ladies' sensibilities were easily offended, this was called a swoon.
Some people faint at the sight of blood. Some parents faint when their child get immunized. Many types of emotional and physical stressors can
overstimulate stimulate the vagus nerve, thus causing dizziness, lightheadedness,
and at times fainting (passing out). An important note: on occasion, the cause of the faint is not vasovagal syncope but
a condition more serious.
If the situation does not appear normal (for example, the person dos not regaining
consciousness quickly) it may be wise to seek medical care or activate the
emergency response system in your area (or call 911 if available).
Dizziness and vertigo
Vertigo is often described as
feeling dizzy, or a sensation of spinning. The patient may specifically mention that the room seems to be spinning
around them. Sometimes the complaint is loss of balance or loss of equilibrium.
This often occurs because of irritation in the inner ear (the part of the ear that
involves
balance, not hearing).
The inner ear has two parts that help the body determine its position in
space relative to gravity; 1) the semicircular canals and, 2) the vestibule.
There are three
semicircular canals that are aligned at right angles to each other. These canals
are filled with fluid and are lined with a nerve-filled, crystal-encrusted
membrane that transmits information to the cerebellum
(the part of the brain
that controls balance and coordination). The cerebellum collects information
from visual stimuli and the nerve endings in muscles associated with proprioception
(the
perception of movement), to assist the brain in assessing where the body is in relationship to
gravity and its surroundings.
Normally, when the head moves, fluid in the semicircular canals shift, and
that information is relayed to the brain. When the head stops moving, the fluid
stops as well, and that information is relayed to the brain.
In some cases there may be a short delay in the transmission of this
information to the brain. For example, when a person rides on a merry-go-round or spins quickly around
in circles, the fluid in the canals develop momentum and even though the body
stops spinning, the fluid in the semicircular canals may continue to move. This causes vertigo, or a
sensation of spinning, and may cause the person to fall or stumble. It also may be associated with
vomiting.
- Inflammation: In patients with vertigo,
inflammation of the fluid or irritation of the
crystals on the membrane that lines the walls of the semicircular canals may
cause the spinning sensation even without much head movement. Often, only one
canal is involved and the patient may be symptom-free if they don't move.
- Benign paroxysmal positional vertigo (BPPV):
BPPV may be caused when the crystals
in the inner ear become dislodged and irritate the semicircular canals. Often
the cause is not found, but there may be an association with unusual positioning
or movement of the head. It is most frequently seen in people older than 60
years of age.
- Labyrinthitis:
Labyrinthitis may follow a viral infection which causes inflammation within
the middle ear.
- Meniere's disease:
This condition is a disorder of the flow of fluids of the inner ear; symptoms
include
vertigo, hearing loss, and tinnitus (ringing in the ears).
- Acoustic neuroma:
This is a benign
tumor of the ear that can present with vertigo.
- Brain: Much less commonly, the cause of vertigo may arise in
the brain. Stroke, tumors,
seizures and
multiple sclerosis may be associated with vertigo.
Next: How is dizziness treated? »
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