Disc bulge

What it means

Between each pair of spinal bones is a soft, rubbery cushion that absorbs shock and lets the spine bend. A bulge is when that whole cushion spreads out a little wider than it should, like a tyre that's flattened slightly under the weight of a car. The cushion is still in one piece — nothing has cracked, torn, or pushed out through a hole — it has just settled outward as it ages and loses water.

Why it appears on a CT or MRI report

Radiologists describe the finding when the cushion's outer rim extends evenly past the edges of the bones above and below. Reports usually note the level (for example L4-L5 or C5-C6), whether the bulge is broad and even or leaning to one side, and whether it touches or presses on nearby nerves. A bulge that is symmetrical and not touching nerve roots is often listed under "degenerative changes" rather than treated as the main finding.

What it usually means

This is one of the most common findings on spine imaging, especially after age 30, and most people who have one feel nothing from it. Studies that scanned pain-free volunteers found bulges in roughly half of adults in their 40s and an even higher share in older groups. The cushion dries out and flattens as part of normal ageing, the same way skin loses elasticity. A bulge becomes clinically interesting only when it sits next to a nerve or narrows the space the nerves travel through — and even then, the picture has to match what you actually feel. Back pain has many sources, and a bulge seen on a scan is rarely the whole explanation by itself.

When to follow up

If the report describes a simple bulge with no nerve contact, there is usually nothing to do beyond the everyday care of your back — staying active, building core and hip strength, and avoiding long stretches of poor posture. Talk to your doctor if you have leg or arm pain that follows a clear path, numbness or weakness in a limb, or pain that wakes you at night. Sudden weakness, loss of bladder or bowel control, or numbness in the saddle area is a red-flag emergency.

A plain-language way to picture it

Imagine a jelly donut stacked between two books. When the books press down, the donut squashes evenly outward, so its edge sticks out a little past the books on every side. The jelly inside is still where it should be and the dough hasn't split. That gentle, all-around squashing is the picture of a bulge — a tyre under load, not a burst inner tube.