What are cranial neuropathies?
Nerves power your entire body. But
those nerves can be damaged by injury or an illness such as diabetes. Neuropathy is a
disorder of nerve damage. It affects your ability to feel and move. Exactly how your
body and your movement are affected depends on where in the body the damaged nerves are
located. When nerves in the brain or brainstem are affected, it is called cranial
The cranial nerves are those that
arise directly from your brain or brainstem. They often affect areas like the face and
eyes. Some of the different types of cranial neuropathies are:
Bell palsy. This health problem
occurs when the facial nerve (seventh cranial nerve) is affected.
Microvascular cranial nerve palsy.
This health problem affects 1 or more nerves, typically those that go to the eye. It
is most common in people who have diabetes and high blood pressure.
Third nerve palsy. This condition
affects the third cranial nerve. This nerve helps manage muscles that control eye
movement, as well as the size of the pupil.
Fourth nerve palsy. This is also
called superior oblique palsy. It affects the superior oblique muscle, which helps
you converge your eyes (to look at the tip of your nose).
Sixth nerve palsy. This is also
called cranial nerve VI or abducens palsy. It affects the sixth cranial nerve, which
also helps control eye movement.
If several different cranial nerves
are affected, it is called multiple cranial neuropathies (MCN).
What causes cranial neuropathies?
Cranial neuropathy can develop for
many different reasons. These include:
Infections. Infections in the spinal fluid can
irritate cranial nerves. For example, Lyme disease often affects the seventh
nerve. But it can cause problems with any cranial nerve.
Cancer. Cancer cells can spread to the spinal fluid
and damage one or more cranial nerves. Sometimes cancer can press on cranial
nerves as they run through the skull.
Increased intracranial pressure from a tumor, head trauma,
or brain swelling. This can injure cranial nerves. Pressure can also be
raised in certain headaches. Cranial nerves 3, 4, and 6 are most often
Congenital cranial neuropathies. These are nerve
injuries from trauma that occurs at birth. Or they can occur before birth from
developmental problems or infection.
Microvascular cranial nerve palsy. This can develop in
people who have high blood pressure or other vascular risks, such as diabetes or
smoking. Poor circulation to the cranial nerves injures them. It most often
affects cranial nerves 3, 4, and 6.
Autoimmune abnormalities. These occur when the immune
system attacks one's own cranial nerves. This can happen in Guillain-Barre
syndrome or lupus.
Aneurysm. This can press on nearby nerves. It most
often affects cranial nerves, 3, 4, and 6.
What are the symptoms of cranial neuropathies?
Different types of neuropathies can
cause different symptoms. They are based on which nerves are damaged and where they are
located. Generally, neuropathies can cause:
Some of the symptoms of different
types of cranial neuropathies include:
Bell palsy can cause drooping of part
of the face. It usually only affects one side of the face.
Microvascular cranial nerve palsy can
cause double vision, droopy eyelid, and other problems with eyesight.
Third nerve palsy can cause an eyelid
to sag and droop, double vision, trouble moving the eye, and a pupil that is bigger
Fourth nerve palsy causes the eye or
eyes to turn abnormally. It sometimes makes you see double. It may force you to tilt
your head when looking.
Sixth nerve palsy can cause abnormal
movement of the eye and double vision.
How are cranial neuropathies diagnosed?
A healthcare provider will often do
a variety of tests to diagnose neuropathy. Depending on the type of cranial neuropathy
your healthcare provider suspects, you may need:
Nervous system exam to test sensation,
reflexes, balance and mental status
Electromyography (EMG), which measures
the electrical activity of muscles when working and at rest
CT or MRI scans, which are imaging
tests that allow healthcare providers to see the brain
Nerve conduction velocity tests to
help find out how and where the nerve is damaged
Biopsies of the skin and nerves to
find out how severely nerves are damaged
Spinal tap (lumbar puncture) to look for infection or
inflammation in the spinal fluid
Angiography, a special X-ray that uses
contrast dye and takes pictures of your heart and blood vessels
How are cranial neuropathies treated?
A cranial neuropathy could be the
sign of a life-threatening emergency. It should be assessed by a healthcare provider
right away. Many types of cranial neuropathies will get better with time, without any
treatment. Sometimes medicines can be used to treat an infection, help reduce swelling
in or near a nerve, or help if the neuropathy is causing pain. For some types of
neuropathies and in some cases, surgery may help. Other times, the nerve damage can't be
treated or fixed.
But it's important to diagnose and
treat any health conditions that are causing the neuropathy. Treating common causes like
high blood pressure, infections, and diabetes can help to treat the neuropathy. Eating
nutritious foods, avoiding smoking, and limiting alcohol can also help manage
Can cranial neuropathies be prevented?
Cranial neuropathy can't always be
prevented. But controlling common causes can help to reduce the risk of developing
neuropathy. You can:
Reduce your risk factors for stroke and head injury
Manage your diabetes well, if you have the disease
Lower your blood pressure, if needed
Living with cranial neuropathy
Cranial neuropathies are often not
dangerous. They may get better on their own with time. But they can certainly be
bothersome for the people who have them.
Your best strategy for managing a
cranial neuropathy is to manage possible causes. These include diabetes, high blood
pressure, infections, and brain tumors. You should also prevent head injury.
If the symptoms do not go away on
their own, your healthcare team might recommend physical therapy, occupational therapy,
or other options to help with them. Talk with your healthcare provider about other
possible options, such as surgery, if a cranial neuropathy is affecting your quality of
When should I call my healthcare provider?
If you have been diagnosed with a
cranial neuropathy, talk with your healthcare providers about when you might need to
call them. They will likely advise you to call if your symptoms get worse or if you
develop new symptoms such as pain, numbness, weakness, or changes in vision.
Key points about cranial neuropathies
Cranial neuropathies are caused by
damage to one or more cranial nerves. These are nerves that arise directly from the
brain. They affect movement and feeling in the eyes and face.
The causes of cranial neuropathies
include poorly controlled diabetes or high blood pressure, head injuries, infections,
strokes, and brain tumors.
Common symptoms can include weakness
or loss of sensation in part of the face, or changes in vision.
Some cranial neuropathies go away on
their own. But others might be permanent. Controlling diabetes and high blood
pressure can sometimes help. If symptoms do not go away, medicines, surgery, or other
treatments might be helpful as well.
Tips to help you get the most from
a visit to your healthcare provider:
Know the reason for your visit and
what you want to happen.
Before your visit, write down
questions you want answered.
Bring someone with you to help you ask
questions and remember what your provider tells you.
At the visit, write down the name of a
new diagnosis, and any new medicines, treatments, or tests. Also write down any new
instructions your provider gives you.
Know why a new medicine or treatment
is prescribed, and how it will help you. Also know what the side effects are.
Ask if your condition can be treated
in other ways.
Know why a test or procedure is
recommended and what the results could mean.
Know what to expect if you do not take
the medicine or have the test or procedure.
If you have a follow-up appointment,
write down the date, time, and purpose for that visit.
Know how you can contact your provider
if you have questions.