You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Cranial nerve disease and explain in detail?
Cranial nerve disease is an impaired functioning of one of the twelve cranial nerves.  Although it could theoretically be considered a mononeuropathy, it is not considered as such under MeSH.
It is possible for a disorder of more than one cranial nerve to occur at the same time, if a trauma occurs at a location where many cranial nerves run together, such as the jugular fossa. A brainstem lesion could also cause impaired functioning of multiple cranial nerves, but this condition would likely also be accompanied by distal motor impairment.
A neurological examination can test the functioning of individual cranial nerves, and detect specific impairments.

Facial nerve palsy
The facial nerve is the seventh of 12 cranial nerves. This cranial nerve controls the muscles in the face.  Facial nerve palsy is more abundant in older adults than in children and is said to affect 15-40 out of 100,000 people per year. This disease comes in many forms which include congenital, infectious, traumatic, neoplastic, or idiopathic. The most common cause of this cranial nerve damage is Bells palsy (idiopathic facial palsy) which is a paralysis of the facial nerve.  Although Bells palsy is more prominent in adults it seems to be found in those younger than 20 or older than 60 years of age.  Bells Palsy is thought to occur by an infection of the herpes virus which may cause demyelination and has been found in patients with facial nerve palsy.  Symptoms include flattening of the forehead, sagging of the eyebrow, and difficulty closing the eye and the mouth on the side of the face that is affected.  The inability to close the mouth causes problems in feeding and speech.  It also causes lack of taste, lacrimation, and sialorrhea.The use of steroids can help in the treatment of Bells Palsy