Cranial neuropathy is a condition in which some of the nerves in the cranium, or skull, have become damaged. The nerves control functions such as vision, hearing, facial movement and the actions of some of the organs in the head, chest, and abdomen. It is usually a secondary problem caused by another medical condition. Damage to these nerves can occur from many causes, with a common one being diabetes. In many cases, neuropathy symptoms clear up within a few months.
There are 12 pairs of nerves located in the cranium; cranial neuropathy is when one or more of these pairs becomes injured. Damage to a single nerve is sometimes called cranial mononeuropathy. Damage to these nerves can cause abnormal functioning of one of the many diverse areas that they govern. The cranial nerves control sight, hearing, taste, smell, and facial movement. Some nerves also regulate certain glands, control swallowing, and the automatic functioning of chest and abdominal organs such as the heart and stomach.
Cranial neuropathy can prompt a wide range of symptoms depending on which nerve is damaged. Occasionally a complication called trigeminal neuralgia occurs, resulting in severe facial pain. One of the most common cranial neuropathies is damage to the seventh, i.e., the facial nerve. This can cause facial pain focused near one of the eyes and paralysis of the eye muscles. Other complications can also occur including facial tics, twitches, spasms, or Bell's palsy, which is partial or full paralysis of the face.
Another common cranial neuropathy is when damage occurs to the oculomotor or third nerve; symptoms can include drooping of the eyelid, pain behind the eye, and double vision. Damage to the vagus or tenth nerve can cause difficulty swallowing, speech impairments, and altered organ functioning. This can result in symptoms including a reduced heart rate, low blood pressure, and stomach difficulties. Cranial neuropathy involving the hypoglossal or twelfth nerve can include symptoms such as weakness of the tongue causing difficulty eating or speaking.
Cranial neuropathy occurs as a secondary problem arising from a wide variety of other medical conditions. Diabetes frequently causes it as part of diabetic neuropathy which affects nerves all over the body. It can also be caused by a range of medical conditions including HIV/AIDS, cancer, Lyme disease, head injury, and infections. In many cases, symptoms may improve on their own and disappear within two to three months. In some instances, however, the damage is permanent.