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 that causes nerve damage and 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 neuropathy.
The cranial nerves are those that arise directly from your brain or brainstem and often affect areas like the face and eyes. Some of the different types of cranial neuropathies include:
Bell's palsy. This condition occurs when the facial nerve (seventh cranial nerve) is affected.
Microvascular cranial nerve palsy. This condition affects the nerves in the eye. It is most common in people who have diabetes and in those who have high blood pressure.
Third nerve palsy. This condition affects the third cranial nerve. This nerve helps manage a muscle that controls eye movement.
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. For example:
- Bell's palsy is often caused by a virus that causes swelling. This puts pressure on the facial nerve.
- Microvascular cranial nerve palsy can develop in people who have high blood pressure.
- Children are sometimes born with third nerve palsy. But it may also be caused by a head injury or an infection. A disorder affecting the brain, such as an aneurysm or brain tumor, may also cause third nerve palsy. Diabetes and migraines are other possible causes.
- Fourth nerve palsy is often a congenital birth defect, which means that a baby is born with it. But a head injury, stroke, or tumor can also cause fourth nerve palsy.
- The sixth cranial nerve can be damaged by infection, a stroke or tumor, increased pressure in the brain, and even migraines.
What are the symptoms of cranial neuropathies?
Different types of neuropathies can cause different symptoms, based on which nerves are damaged and where they are located. Generally, neuropathies can cause:
- A tingling sensation
- Skin that feels sensitive to the touch
- Weak or paralyzed muscles
Some of the symptoms of different types of cranial neuropathies include:
Bell's 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 and other problems with eyesight.
Third nerve palsy can cause an eyelid to sag and droop, double vision, difficulty moving the eye, and a pupil that is bigger than normal.
Fourth nerve palsy causes the eye or eyes to turn abnormally. It sometimes makes you see double and 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 usually do a variety of tests to diagnose neuropathy. Depending on the type of cranial neuropathy your doctor suspects, tests may include:
- Neurological 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 techniques 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.
- Hearing tests
- Angiography, a special X-ray that uses contrast dye and takes pictures of your heart and blood vessels.
How are cranial neuropathies treated?
Many types of 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 repaired.
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 neuropathy.
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. Reducing your risk factors for stroke and head injury, managing your diabetes well, and lowering high blood pressure can all be helpful in preventing neuropathy.
Living with cranial neuropathy
Cranial neuropathies are usually not dangerous and 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 life.
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 and affect movement and sensation 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.