Nasal septal deviation

What it means

The nasal septum is the thin wall of cartilage and bone that divides the inside of the nose into a left and right passage. In a perfectly straight septum, both passages would be equal in size, but in reality very few people have one — most septums curve, bow, or tilt slightly to one side. When a radiologist notes a "deviation," they are simply describing which way and how far that internal wall leans off center.

Why it appears on a CT or MRI report

Because the paranasal sinuses sit right next to the nasal septum, any CT or MRI that includes the sinuses or the head will show the septum along the way, whether or not sinus symptoms were the reason for the scan. Radiologists often mention it as an incidental observation, sometimes noting the direction of the curve (left or right) and, occasionally, whether it appears to be narrowing one nasal passage enough to plausibly explain breathing difficulty on that side.

What it usually means

Studies suggest that a majority of adults have some degree of septal deviation, and for most people it causes no symptoms at all — it's simply part of individual anatomy, much like being right- or left-handed. It can be present from birth or develop gradually, and it's also commonly caused or worsened by a nose injury at some point in life, even a minor one from childhood that's long forgotten. Only when the deviation is pronounced enough to significantly block one nasal passage does it tend to cause noticeable symptoms, such as chronic nasal congestion favoring one side, snoring, difficulty breathing through the nose during exercise, or a tendency toward sinus infections on the narrowed side.

When to follow up

If the deviation is mentioned as an incidental finding with no symptoms, it typically needs no action at all — it's simply a description of your anatomy. Talk to your doctor if you have ongoing one-sided nasal congestion, trouble breathing through your nose, frequent sinus infections, or snoring that's affecting your sleep, since these symptoms — combined with a significant deviation — are what would prompt a referral to an ear, nose, and throat specialist. Treatment, if needed at all, ranges from medications to manage congestion to a surgical procedure called a septoplasty for more significant cases.

A plain-language way to picture it

Picture a hallway divider wall in an older building that was never installed perfectly straight — it leans slightly to one side, making one corridor a bit narrower than the other. People walk through both corridors every day without noticing, because there's still plenty of room to pass. Only if the wall leaned dramatically, squeezing one corridor down to a tight gap, would it actually start to slow foot traffic. Most nasal septal deviations are like the gently leaning wall — a quirk of construction, not an obstacle.