Dizziness (Dizzy) (cont.)

Vertigo is often described as feeling dizzy, or a sensation of spinning. A person 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 the eyes (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. While these are symptoms attempt to provoke in play, they can be debilitating for an adult.

• 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, for example, moving the head up and down while working on a computer. It is frequently seen in people older than 60 years of age.
  
  
• Labyrinthitis: Labyrinthitis (labyrinth=inner ear + itis=inflammation) 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 be 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.

Source: MedicineNet.com
http://www.medicinenet.com/dizziness_dizzy/article.htm