nervous system is a complex, highly specialized network. It organizes,
explains, and directs interactions between you and the world around you. The
nervous system controls:
- Sight, hearing, taste, smell, and feeling
- Voluntary and
involuntary functions, such as movement, balance, and
coordination. The nervous system also regulates the actions of most other body
systems, such as blood flow and blood pressure.
- The ability to
think and reason. The nervous system allows you to be conscious and have
thoughts, memories, and language.
The nervous system is divided into the brain and spinal cord
(central nervous system, or CNS) and the nerve cells
that control voluntary and involuntary movements (peripheral nervous system, or PNS).
The symptoms of a nervous system problem
depend on which area of the nervous system is involved and what is causing the
problem. Nervous system problems may occur slowly and cause a gradual loss of
function (degenerative). Or they may occur suddenly and cause life-threatening
problems (acute). Symptoms may be mild or severe. Some serious conditions,
diseases, and injuries that can cause nervous system problems include:
- Blood supply problems (vascular disorders).
- Injuries (trauma), especially injuries to the
head and spinal cord.
- Problems that are present at birth
- Mental health problems, such as
- Exposure to toxins, such as
carbon monoxide, arsenic, or lead.
- Problems that cause a gradual
loss of function (degenerative). Examples include:
- Infections. These may occur in the:
- Overuse of or withdrawal from
prescription and nonprescription medicines,
illegal drugs, or alcohol.
- Organ system failure.
- Respiratory failure.
- Liver failure (hepatic encephalopathy).
- Other conditions. Some examples include:
A sudden (acute) nervous system problem can cause many
different symptoms, depending on the area of the nervous system involved.
transient ischemic attack (TIA) are common examples of
acute problems. You may experience the sudden onset of one or more symptoms,
- Numbness, tingling, weakness, or
inability to move a part or all of one side of the body (paralysis).
- Dimness, blurring, double
vision, or loss of vision in one or both eyes.
- Loss of speech,
trouble talking, or trouble understanding speech.
- Sudden, severe
- Dizziness, unsteadiness, or the inability to stand or
walk, especially if other symptoms are present.
- Confusion or a change in
level of consciousness or
- Severe nausea or
Seizures can also cause sudden changes in
consciousness, feeling (sensation), emotion, or thought. Abnormal body
movements, such as muscle twitching, may or may not be present. How often the
seizures occur and how severe they are depend on the cause of the seizures and
the area of the brain involved. For more information, see the topic