Occipital Plagiocephaly: Flat-Out Controversial
abstract & commentary
Source: Miller RI, Clarren SK. Long-term developmental outcomes in patients with deformational plagiocephaly. Pediatrics 2000;105:E26.
Occipital plagiocephaly (op) is a complex abnormality in head shape involving unilateral or bilateral occipital flattening and some degree of axial asymmetry of the skull base. It is one of the most common abnormalities of skull shape seen in children and although its true incidence is unknown, it is probably quite high, for as many as 14% of adults show morphometric evidence of skull base anterior-posterior asymmetry (Rekate HL. J Neurosurg 1998;89:24-30). The unifying mechanism of OP appears to be an asymmetry of axial forces on the pliable infant skull. It may be due to abnormalities of brain shape, unilateral lambdoid craniosynostosis, and, most commonly, asymmetry of external compressive forces on the skull. The incidence of OP has apparently risen dramatically over the past decade, widely attributed in large part to the April 1992 recommendations by the American Academy of Pediatrics that infants avoid a prone sleep position in order to reduce the incidence of sudden infant death syndrome (Turk AE, et al. J Craniofac Surg 1996;7:12-18).
Recently, it has become clear that only a small fraction of patients with OP have craniosynostosis. In the series of 115 OP patients reported by Mulliken and colleagues (Mulliken JB, et al. Plast Reconstr Surg 1999; 103:371-380), only a single patient had lambdoid craniosynostosis; the remainder of the cases were deformational. This has motivated a sea of change from surgical to nonsurgical management of this condition. The most widely nonsurgical therapy is helmet therapy, particularly dynamic orthotic cranioplasty helmet (or "DOC banding" Littlefield TR, et al. J Craniofac Surg 1998;9:11-17). These helmets are applied to infants between 6 and 18 months of age, are worn almost continuously for (on average) four to six months, and are effective in complete or near-complete correction of cranial asymmetry.
A major point of controversy is whether OP is associated with any significant medical complications. Theoretical complications of OP include dental malocclusion, orbital dystopia with resulting accommodative errors, and increased intracranial pressure, none of which has been proven (Rekate HL. J Neurosurg 1998;89:24-30). Many physicians (and insurance companies) have thus regarded OP as an essentially cosmetic problem. Miller and Clarren now report that developmental difficulties are dramatically increased in children with OP, furthering the controversy.
Miller and Clarren performed a retrospective record review of 254 patients with OP evaluated at a single craniofacial surgery program over an 11-year period (1980-1991). Among these patients, 181 were located, and 63 of these agreed to telephone interview in order to determine developmental outcome some 10-20 years after diagnosis of OP, compared to siblings with normal head shape. A major finding of this study is that 25 of 63 (40%) of children with OP were sufficiently developmentally delayed to require special services (special education; or speech, occupational, or physical therapy) as compared to seven of 91 (8%) of sibling controls. This increased relative risk of development was more marked in males with OP—almost 10-fold as compared to sibling controls. Interestingly, the use of helmet therapy did not influence the incidence of developmental delay (11/27 [41%] in the helmet group and 14/36 [39%] in the nonhelmet group).
The main issue raised by this study is clear: does early skull molding lead to subtle brain dysfunction or is OP simply an early sign of subtle brain dysfunction? The lack of significant difference between the helmet-treated and nontreated groups suggests that either correction of the molding does not influence developmental outcome or the mean age at helmet intervention (about 6 months) is already too late to make a difference. Clearly, a child who is delayed in getting up from a supine to a sitting position (for whatever reason) is plausibly at increased risk of developing OP. A prospective study of the influence of helmet treatment on long-term developmental outcome that uses quantitative and standardized neuropsychological test results will be needed to settle this issue. Also, are the delays seen transient or enduring? If the latter proves to be true, do not be surprised to see more babies crawling about with helmets on. —rt
a. is usually a consequence of occult craniosynostosis.
b. is best managed surgically in most cases.
c. has been clearly associated with medical complications, including dental and visual difficulties.
d. may be associated with developmental delays, especially in boys.
e. has been decreasing in incidence over the past decade.