Plagiocephaly involves fusion of one side of the coronal suture. The coronal suture runs across the top of the skull, almost from ear to ear. The soft spot, or fontanel, is located midway between the right and left coronal sutures and is usually absent, or closed, in plagiocephaly. On the side of the skull where the suture has closed, one can typically feel a raised ridge of bone. When viewed from above, the forehead on the affected side is recessed, or further back than the other side (which typically is further forward than normal in order to compensate for the brain's inability to grow on the affected side). In looking straight on at the child, the eyebrow on the affected side is usually higher and the root, or top of the nose, may be deviated toward the side of the fused suture. Most parents report that their child looks worse when they see their child in a mirror. The reason things look worse in a mirror, may in part be related to the fact that a mirror flips the image around so the right side becomes the left, etc. Instead of seeing your child as you are used to seeing everyday, with the recession on one side, you now see a "different" child with the recession on the opposite side.

The incidence of plagiocephaly is estimated to be about one in 3500 births. Almost all children affected with plagiocephaly require surgical treatment. The treatment for this condition is discussed in the treatment section.