OCCIPITAL PLAGIOCEPHALY - DEFORMATION OR LAMBDOID SYNOSTOSIS .1. MORPHOMETRIC ANALYSIS AND RESULTS OF UNILATERAL LAMBDOID CRANIECTOMY

Between 1987 and 1992, 30 infants aged 1.4-13 months (mean 7.3 months) underwent unilateral lambdoid strip craniectomy at the Children's Hos pital of Buffalo for occipital plagiocephaly. Males outnumbered female s (22:8) and right-sided occipital flattening was significantly more c ommon than left-sided flattening (25:5). The deformity was noticed at an average age of 3.2 months; 16% of the infants had an asymmetry at b irth. Positional preferences (a distinct tendency to lie preferentiall y on the back, in most cases with the head turned to the ipsilateral s ide) were described in 79% of infants for whom this information was av ailable, and torticollis was present in 10%. Pre- and post-operative C T scans were analyzed using several morphometric measurements. Asymmet ries were measured between the flattened and contralateral sides, both posteriorly and anteriorly, using a translucent grid placed over the CT slice showing maximum asymmetry. The average maximum asymmetry betw een the flattened and contralateral sides was 24% posteriorly and 16% anteriorly. Significant improvements were seen postoperatively, with b oth anterior and posterior asymmetries improving by an average of one third (p < 0.05). However, when compared with CT scans from a control group of infants without synostosis, the operated group showed persist ent and significant asymmetries postoperatively. The morphometric meas urements described allow an objective and reproducible means of assess ing the results of various treatments for this disorder. The improveme nts following unilateral lambdoid craniectomy are difficult to interpr et in isolation; we suggest that future efforts be directed toward sim ilarly assessing the results of both nonoperative treatments such as p ositional changes and molding helmets, and more aggressive surgical tr eatments that have been advocated for this disorder.