Topic Overview
The
nervous system is a complex, highly specialized network. It organizes,
explains, and directs interactions between you and the world around you. The
controls:
- Sight, hearing, taste, smell, and feeling
(sensation).
- and
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
(, or CNS) and the nerve cells
that control voluntary and involuntary movements (, 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 ().
- Injuries (trauma), especially injuries to the
head and spinal cord.
- Problems that are present at birth
(congenital).
- Mental health problems, such as
,
, or
.
- 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:
- Brain ( or
).
- Membrane surrounding the brain
and spinal cord ().
-
prescription and nonprescription medicines,
, or alcohol.
- A
.
- Organ system failure.
Examples include:
- Respiratory failure.
- Heart
failure.
- Liver failure (hepatic encephalopathy).
- Kidney
failure (uremia).
- Other conditions. Some examples include:
- Thyroid dysfunction ( or
).
- High blood sugar
() or low blood sugar ().
- .
- Nutritional
deficiencies, such as vitamin B1 (thiamine) or vitamin B12
deficiency.
- .
A sudden (acute) nervous system problem can cause many
different symptoms, depending on the area of the nervous system involved.
and
(TIA) are common examples of
acute problems. You may experience the sudden onset of one or more symptoms,
such as:
- , weakness, or
inability to move a part or all of one side of the body ().
- Dimness, blurring, double
vision, or loss of vision in one or both eyes.
- Loss of speech,
trouble talking, or trouble understanding speech.
- Sudden, severe
headache.
- Dizziness, unsteadiness, or the inability to stand or
walk, especially if other symptoms are present.
- or a change in
or
.
- Severe nausea or
vomiting.
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
Seizures.
Diabetes can cause problems
with balance, either as a result of peripheral neuropathy or stroke.
and
are problems of balance and coordination
(equilibrium). Vertigo is often caused by a
or a problem of the inner ear or brain.
Emotional distress,
, blood pressure problems, and other
diseases can all cause feelings of dizziness. For more information, see the
topic
Dizziness: Lightheadedness and Vertigo.
Most headaches are not caused by serious central nervous system problems.
The pain that comes with a headache can range from a throbbing or a piercing
pain, such as with a
, to severe pain that comes and goes over
several days, such as with
. Headaches are usually caused by
problems with the sinuses, scalp, or muscles of or around the head. For more
information, see the topic
Headaches.
Check your symptoms
to decide if and when you should see a doctor.