Justin Bieber is traveling after facial paralysis diagnosis: What will his recovery be like?

Pop star Justin Bieber, who's suffering from Ramsay Hunt syndrome, was seen in public for the first time over the weekend since he revealed his diagnosis. He and wife Hailey Bieber were spotted touching down at Los Angeles airport on Saturday, according to photos from Shutterstock.

Ramsay Hunt syndrome is a rare disorder caused by a viral infection in the ear, which affects the facial nerve, leading to paralysis. The most recent update on the singer's condition came from his wife Hailey Bieber, who appeared on The Tonight Show Starring Jimmy Fallon earlier this month. "He's going to be totally OK," she told Fallon.

Shortly before that, Bieber shared with fans on Instagram that “each day has gotten better and through all of the discomfort I have found comfort in the one who designed me and knows me (Jesus).” He also called what he's been going through "a horrific storm."

The 28-year-old first shared in an Instagram video on June 10 that one side of his face has become fully paralyzed due to the syndrome. Bieber explained that he is canceling upcoming shows and taking time off to rest and recover.

Since Bieber revealed his diagnosis, the rare neurological condition has gotten a lot of attention. So what is causing Bieber's Ramsay Hunt syndrome, and what might his recovery be like?

Justin Bieber and Ramsay Hunt syndrome: What is it?

Ramsay Hunt syndrome, a type of viral infection named after the neurologist who first described the condition, is also known as herpes zoster oticus. It is a rare disorder characterized by paralysis of the facial nerve and a painful rash in the ear — but only on one side of the head. It's caused by the varicella-zoster virus, the same one that causes chickenpox and shingles.

“(After) someone has chickenpox ... that virus can stay dormant in the nerves for a really long period of time and become reactivated later on,” Dr. Anna Pace, a New York-based neurologist at the Mount Sinai Center for Headache and Facial Pain, told TODAY.

Reactivation of the varicella-zoster virus causes shingles, aka herpes zoster. In rare cases, shingles can occur in the ear and lead to Ramsay Hunt syndrome — where the viral infection spreads to the nearby facial nerve, which controls movement and expression.

“The facial nerve can become inflamed and have swelling, which leads to the inability to move the lower part of the face, move the eyebrows, or close the eyes completely,” Pace said. For example, Bieber explained in Friday's video that he can no longer blink one eye or smile on the left side of his face.

Symptoms vary. In some cases, swelling from the viral infection can affect the cranial nerve that controls hearing and balance. “You can also have ear pain, ringing in the ears, feeling like the room is spinning or vertigo, or sensitivity to sound,” Pace said. Less often, Ramsay Hunt syndrome can cause hearing loss in the affected ear.

People with Ramsay Hunt syndrome, in addition to the paralysis, will usually develop a painful rash inside the ear (which can extend to face, neck, mouth or throat) but not always.

"You don’t have to have the rash to have facial nerve paralysis. ... There are basically two variants: with the rash and without the rash,” Pace explained, adding that without the rash, Ramsay Hunt syndrome can be harder to diagnose.

The most common reason the varicella-zoster virus gets reactivated is stress, Pace said. A person with an active shingles infection can spread the varicella-zoster virus to anyone who has never had chickenpox or received the vaccine.

Will Justin Bieber recover from Ramsay Hunt syndrome?

Ramsay Hunt syndrome is treatable, and most people do recover within three to four months.

“It’s not something that happens overnight," Pace said, adding that the younger and healthier you are, the more likely you are to fully recover.

“We usually treat with steroids, such as prednisone, as well as an antiviral medication specifically targeting the virus,” she continued. Doctors may also prescribe medications to treat other symptoms, such as vertigo or ear pain caused by swelling of the cranial nerves.

Treatment should begin as soon as possible after symptoms start, ideally within three days, Pace said. “If you don’t receive treatment, it’s much harder to recover.”

Some people do get better on their own and recover spontaneously, but it is not common. Only about 20% of people will have complete recovery without treatment, according to Pace.

Bieber mentioned that he's doing facial exercises “to get back to normal,” and Pace confirmed that some data suggests that exercises can help, alongside treatment, to regain facial movement. But early treatment with medication gives the best chance for a full recovery.

In severe cases involving nerve damage, the paralysis can be permanent. Other long-term complications include damaged nerves, facial asymmetry and eye damage. The severity of the paralysis when it starts will also dictate recovery. People with only mild facial paralysis are more likely to fully recovery compared to those with severe paralysis affecting multiple cranial nerves.

“There is a spectrum to what recovery looks like,” Pace said, speculating that the condition could affect Bieber's singing "if he isn’t able to have the same range of motion." Although Bieber has not explicitly commented on the condition’s impact on his singing, he did say he is “physically obviously not capable” of performing.

Bieber stated in his video that he expects to get better: “It will go back to normal, just time. We don’t know how much time that’s going to be, but it’s going to be OK."

Prevention of Ramsay Hunt syndrome

Getting vaccinated is the best way to prevent shingles and its complications. The U.S. Centers for Disease Control and Prevention recommends two doses of the chickenpox vaccine for all children, adolescents and adults who have never had chickenpox. The CDC also advises all adults over 50 and adults over 19 with weakened immune systems receive two doses of the shingles vaccine.

If you ever experience facial weakness or paralysis, call your primary care provider.