This is the rarest form of non-syndromic craniosynostosis, making up only 1-3% of all cases. This can be confused with positional plagiocephaly, as both can cause uneven flattening of the back of the head. Patients with lambdoid suture craniosynostosis have flatness of the back of the head and a downward bulging of the skull behind the ear on the side of the closed suture. There is also a downward tilt of the skull base toward the affected side which can make the back hairline look tilted. The affects on the appearance of the face can range from no affects to significant asymmetry. The ear on the side of the closed suture may be uneven in its position on the head compared with the other ear. Most patients with this form of craniosynostosis have heads that are larger in middle and back thirds of the skull on the side opposite the closed suture. This is due to the sutures on the opposite side making room to compensate for the closed suture opposite them. These patients require an open cranial vault remodeling.