Treatment of functional lambdoid synostosis.

Involvement of the lambdoid suture appears to be somewhat different from that of other cranial sutures because the ability to tell whether this suture is fused is often impossible by clinical examination or imaging studies, with the findings at operation often variable irrespective of the degree of the deformity. Thus, it is best to think in terms of functional unilambdoid synostosis. The diagnostic evaluation is limited to visual inspection alone in most cases. The indication for surgical intervention is the degree of the deformity. Over the past 15 years I have undergone a transition as to the operative management of functional unilambdoid synostosis, starting initially with a strip craniectomy, followed by removal of the flattened portion of the calvarium to removal of the entire posterior portion of the calvarium, including the bone at the cranial base. Parietal asymmetry as a more extensive approach has uniformly produced better cosmetic results without significant increase in morbidity. In infants less than 3 to 4 months of age the bone removed is not replaced, whereas in those older than 4 months of age the bone from the two sides is reversed, rotated, trimmed, and shaped to reach symmetry. Treatment of bilateral lambdoid involvement is the same as when one lambdoid suture is functionally synostosed, although asymmetry is not a consideration. In a nonsyndromic form, operative intervention allows for increase in the anteroposterior diameter of the calvarium, with eventual reduction of the biparietal widening and vertical orientation to the calvarium if performed early enough.(ABSTRACT TRUNCATED AT 250 WORDS)