of focal: occurring
in one particular site in the body.
Focal Neuropathy means that only one
(or at most a few) nerves are injured. The
pain, numbness and/or weakness are confined to a
single limb or a small area of the body or the
neuropathy is far less common than peripheral or
autonomic neuropathy which means that many
nerves may be involved.
Focal neuropathy is usually caused by
compression or trauma. Basically, one nerve gets
damaged. The best known of these is carpal tunnel
syndrome where the median nerve (the nerve that goes
down the arm and through the carpal tunnel which is in
the wrist) is damaged by compression of that nerve.
Focal Neuropathy can cause sudden
weakness or pain. It can lead to double vision, a
paralysis on one side of the face (called Bell's
palsy), or a pain in the front of the thigh or other
parts of the body.
A focal neuropathy results from an
injury to a peripheral nerve at one site. For every
nerve there are anatomical weaknesses making injury
more likely at a particular location, typically this
is where a nerve runs beside bone or across a joint.
Nerve injury can occur from:
External occurrence: This can be direct trauma,
including prolonged external compression (edema from
pregnancy, prolonged unconsciousness, etc.), repeated
minor trauma, traction, injection, cold, burns,
Internal entrapment or compression:
examples would include entrapment of the median nerve
(nerve in the arm) in the carpal tunnel (in wrist) or
the ulnar nerve (arm) in the cubital tunnel
(elbow). It can also occur with compression
by tumors, deposits or vascular malformations
Intrinsic lesion to the
nerve. It is a blockage of the nerve
function. It can be from an infarct,
or blockage of blood to a nerve. It can be
caused by, a nerve infarct caused from inflammation of
the blood vessel, an area where the nerve impulse is
Increased susceptibility to
nerve injury—for example, in diabetes—combined
with minor entrapment or compression.
Diabetic focal neuropathy,
sometimes called mononeuropathy, affects a single
nerve, most often in the wrist, thigh, or foot. It may
also affect the nerves of the back and chest, as well
as those that control the eye muscles.
Pain in a single, limited area of the
body, such as a wrist or foot.
When focal neuropathy causes nerve entrapment,
soreness and pain may develop gradually over several
weeks or months.
Pain in and around one of the eyes,
problem with moving the eyes and double vision. This
occurs when one of the cranial
Pain that occurs in a band-shaped area
around the chest or abdomen.
pain in the lower back, often extending to the thigh
(femoral neuropathy), sometimes causing paralysis.
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