Ramsay Hunt syndrome is a neurological condition caused by varicella zoster virus, the same virus that causes chickenpox in children and shingles in adults. The virus can linger in your body for your entire life, even long after you have recovered from chickenpox, and reawaken to irritate and inflame the nerves in your face.

The illness affects men and women equally and can result in paralysis on one side of the face and painful, blistering rashes. It is more common in older people, and some patients experience changes in their hearing, perhaps perceiving sounds louder in one ear than another or developing tinnitus (a chronic ringing in the ears) or even deafness in one ear.

Ear and facial pain is commonly a part of the syndrome, and some patients may suffer from vertigo.

Only about five to 10 out of every 100,000 people will develop Ramsay Hunt syndrome each year. “It can happen to anyone,” said Dr. Waleed Javaid, director of infection prevention and control

The syndrome is officially known as herpes zoster oticus; its more common name comes from the neurologist James Ramsay Hunt, who first described the illness.

It can take a long time for people with the syndrome to receive an accurate diagnosis, according to researchers. The term Ramsay Hunt is notoriously vague and the illness can have symptoms similar to Bell’s palsy,

Most people who have Ramsay Hunt make a full recovery, although the duration of the disease can vary, said Dr. Michael Ison, a professor of infectious diseases at Northwestern Feinberg School of Medicine.

Treatment for Ramsay Hunt typically involves taking anti-viral medication. Some patients may also be prescribed a steroid, Dr. Wald said. Physical therapy is not usually recommended for patients, she said, but would not be harmful.

Justin Bieber announced Friday that he is taking a break from performing because he is suffering from paralysis on one side of his face.

Mr. Bieber said in his Instagram post that he was practicing facial exercises as part of his healing. “I gotta go get my rest on,” he said, “so I can get my face back to where it’s supposed to be.”