He would wake up with a wet pillow and ear. But he never would have guessed what that fluid was.

No matter what he did, the fluid just kept leaking out of his ear. Mark Hoffman would wake up in the morning to find his pillow soaking wet. He’d put a cotton ball in his ear to soak up the fluid and soon it would be saturated with liquid.

It took 10 years and multiple inquiries for Hoffman, 53, who lives in Akron, Ind., to find a doctor who could correctly diagnose the problem.

The verdict? In medical terms, a cerebrospinal fluid leak. Or, in terms that might make us laypeople wince, Hoffman had brain and spinal fluid oozing out of his right ear and even at times out of his right nostril.

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It’s a condition that’s becoming more common, says Dr. Rick Nelson, neurotologist at Indiana University Health, who performs surgery to correct this problem.

Often Nelson can simply look at the fluid to confirm his suspicion that a person has a leak.

“When I look in the ear and in the ear tube, the fluid that comes out is more clear and it doesn’t look like an infection,” he said. “It kind of pulsates, like a heartbeat. If you suck it out, it will come out, like a leaky faucet.”

Spontaneous cerebrospinal fluid leaks occur when there’s a loss of bone in the shelf of bone between the brain and the ear and a hole develops in the membrane bag that surrounds the brain, called the dura. Such leaks can also result from trauma.

Incidence of this condition has more than doubled in the past decade, Nelson said. About 10 years ago, he performed two to four of these procedures every six to 12 months. Now, he does one to four such operations a month.

Some of the increase can be attributed to better diagnosis. As Hoffman learned, often doctors misidentify this condition, which tends to be more common in women than men and in those who are middle-aged.

Doctors know that the rise in obesity may play a role, but they’re not exactly sure why.

Nelson suspects that another condition common in the obese, obstructed sleep apnea, may be to blame. People with obstructed sleep apnea stop breathing several times throughout the night, elevating the pressure in their heads each time. Over time this elevated pressure may erode the bone and the spinal fluid can start to leak out of the ear, as happened in Hoffman’s case.

At first, the leak was so minor that Hoffman attributed to water in his ear from a shower. When it got worse, he figured it was an ear infection. Then last year, he started losing hearing in his right ear. A doctor said Hoffman had damaged his mastoid bone and required surgery.

After that, his ear started leaking constantly.

“It was dripping every 10 seconds,” he said. “I used over 5,000 cotton balls in my ear. About every 30 to 45 minutes, you could squeeze it and fluid would be running out of the cotton ball.”

As Hoffman learned, the body maintains a never-ending supply of this fluid. Even people without leaks make and reabsorb spinal fluid about twice a day. If there’s a leak, the body just makes more, Nelson said.

Leaks open the person to developing meningitis, a potentially fatal infection of the brain. About 15 to 20 percent of people who have a leak learn of the problem once they have been diagnosed with meningitis, Nelson said.

“That’s the reason we want to fix this, because of the risk of meningitis, and it’s super annoying to have the fluid,” he said.

The only fix consists of a three-hour surgery in which Nelson repairs the bone with a piece of the patient’s skull bone and patches the dura with tissue taken from the muscle over the ear.

Leaks that occur as a result of trauma usually resolve on their own.

But Hoffman underwent surgery in December 2016. Since then, his hearing loss has continued. Nevertheless, he said, he feels glad he had the procedure.

“I feel better since the surgery. It’s a relief,” he said. “Number one, it’s not leaking anymore, and then you have to always worry about the brain fluid coming out of your ear.”

Call IndyStar reporter Shari Rudavsky at (317) 444-6354. Follow her on Twitter and Facebook.