OCCIPITAL PLAGIOCEPHALY - DEFORMATION OR LAMBDOID SYNOSTOSIS .2. A UNIFYING THEORY REGARDING PATHOGENESIS

Occipital plagiocephaly is characterized by both unilateral occipital flattening and ipsilateral frontal prominence with anterior deviation of the ipsilateral ear, yielding a characteristic parallelogram shape to the cranium. Radiographic changes in the lambdoid suture are often evident, but the lambdoid suture is usually patent over most or all of its length on skull X-rays and/or CT scans. Both lambdoid synostosis and deformational forces have been implicated as potentially causal in the pathogenesis of this deformity. We propose a unifying theory whic h incorporates a common pathogenesis for both deformational plagioceph aly and most cases of lambdoid 'synostosis'. According to this hypothe sis, intrauterine and/or postnatal deformational forces are responsibl e for the primary calvarial deformation. These forces initially act in a reversible manner to produce the typical parallelogram-shaped skull deformity. However, with continued deformation, more enduring seconda ry pathological changes may eventually occur in the lambdoid suture an d basicranium which are more difficult to correct even if the offendin g deformational forces are subsequently removed or reversed.