Brain Tumors and Mysterious Fluid Leaks: What the Data Reveals

Doctors have long wondered why some people with harmless brain tumors suddenly leak clear fluid from their nose or ears. A closer look at three new patient cases and a big review of past research helps explain what might be going on.

In each of the three new cases, the fluid leak happened on the same side as the tumor. One patient had a hormone-making tumor in the pituitary gland and leaked fluid from the nose. Another had a rare growth near the center of the brain and also leaked from the nose, along with fluid building up inside the skull. The third patient had a tumor near the ear and leaked fluid from the ear.

Researchers then looked at 125 studies, but only 28 fit what they needed. The average age of patients was 42, and there were slightly more men than women. The most common tumor was a type called a prolactinoma, often found in the sella area at the base of the brain. About 4 in 10 tumors sat right in the middle, while roughly a third were on the right side and a quarter on the left.

The sphenoid sinus was the top spot where leaks started, showing up in nearly 40% of cases. Fluid came out of the right nostril in about 39% of patients, the left nostril in another 39%, and both nostrils in about 1 in 10. Some people leaked from the ear, and a few leaked from both the nose and ear. About 1 in 4 patients also had extra fluid around the brain, known as hydrocephalus.

Even though the new cases showed leaks on the same side as the tumor, the bigger picture told a different story. The review found that left-sided nose leaks happened just as often, even when tumors were in the middle or on the right. This means simply looking at where the tumor sits isn't enough to predict where the leak will come from. Doctors need to ask detailed questions, use strong imaging tools, and check for fluid buildup to find the real source and avoid serious problems like repeat infections in the brain lining.