Dizziness is a sensation of spatial disorientation that can lead to a loss of balance. The term dizzy is frequently used to describe feelings of weakness, faintness and lightheadedness. Dizziness may also be accompanied by any combination of the following symptoms:

• Unsteadiness, wooziness or giddiness
• Nausea
• Sweating
• Headache
• Visual difficulties
• Confusion or poor concentration
• Fatigue

Dizziness is related to the body’s sense of balance or equilibrium. Maintaining a sense of balance depends on the ability of the central nervous system (composed of the brain and spinal cord) to process a variety of information from sensory systems including:

• Vestibular system. The inner ears monitor directions of motion, such as turning, up and down, forward and backward and side-to-side movements.
  
  
• Visual system. The eyes monitor the body’s position in space, such as right side up or upside down, as well as directions of motion.
  
  
• Proprioceptive system. Sensory receptors in the skin, muscles, ligaments and joints provide awareness of the position and movement of the parts of the body. This sense is known as proprioception.

Balance relies on functioning of at least two of these sensory systems. For instance, individuals can close their eyes while washing their hair in the shower without losing their balance. This is because signals from the sensory nerves and inner ear help ensure that a person remains upright.  

Dizziness and loss of balance can also result when:

• The brain is unable to process signals from the sensory systems
  
  
• The messages sent by the sensory systems are contradictory

Dizziness typically occurs while moving the head, standing or walking, and the sensation may be alleviated by sitting or lying down. Most causes of dizziness are not critical, and the condition, which often dissipates on its own, is often easily treated.

Physicians generally associate four disorders with dizziness:

• Vertigo. The patient feels as though the surrounding environment is moving, or experiences a sensation of spinning or falling. Vertigo is frequently accompanied by nausea and vomiting. The two types of vertigo are:
  
  
• • Peripheral. Vertigo caused by a problem in the vestibular labyrinth, the part of the inner ear that controls balance.
    
    
  • Central. Vertigo caused by an abnormality of the brain, particularly in the cerebellum (lower back section of the brain) or brainstem.
    
    
• Disequilibrium. Disequilibrium is described as a sense of imbalance or a feeling that a fall is imminent. This sensation, which typically involves the legs rather than the upper torso and head, occurs most often while the patient is standing and can be alleviated by sitting or lying down.
  
  
• Presyncope. People who experience presyncope feel as though they are about to faint. This sensation may begin with ringing in the ears (tinnitus) or diminished vision.
  
  
• Nonspecific dizziness. This term is given to vague sensations of lightheadedness or wooziness that cannot be identified as vertigo, disequilibrium or presyncope.

Experts recommend that individuals experiencing dizziness need to be careful not to injure themselves or others, and should avoid participating in potentially dangerous activities, such as driving a car or operating heavy machinery.