|Posterior plagiocephaly involves a
fusion of the lambdoid suture.. It has a right and left
side and is shaped like an upside down "V." Usually,
only one side fuses shut, but rarely both sides will be
closed. When viewed from above, the affected side of the
back of the head is flatter than the opposite side. One
key marker for fusion of the lambdoid suture is a low
bump behind the ear on the same side as the fused
suture. Another good way to determine if the lambdoid
suture is closed is to look and see if the ear on the
same side as the posterior skull flatness is pulled
backwards and sticks out more. If the ear is forward on
the flat side, with respect to the opposite ear, then a
skull deformation should be suspected instead of a fused
suture. It is critically important to determine whether
or not the child truly has a fused suture because skull
deformations almost never need to be surgically treated.
Ideally, the diagnosis of lambdoid synostosis is made by
CT scans, read at an experienced center. Children who
have lambdoid synostosis and significant flattening of
the skull do require surgery to fix this condition.
The incidence of posterior plagiocephaly is
currently unknown and is probably even more rare than
one in 100,000 births.