Long-term developmental follow-up in children with nonsyndromic craniosynostosis.

OBJECT: The aim of this study was to determine the distribution of Full Scale IQ (FSIQ) by type of craniosynostosis and to verify the finding that at long-term follow-up, verbal IQ (VIQ) is significantly higher than performance IQ (PIQ) in patients with single-suture sagittal synostosis (SS) despite falling within the "average" range for intelligence. Whether this also occurs in other types of craniosynostosis and whether surgery and sex are relevant were also determined. The relationship between age at time of surgery and later IQ was ascertained.

METHODS: The data for 91 children with craniosynostosis (47 sagittal, 15 unicoronal, 13 metopic, 9 multisuture, and 7 bicoronal) were collected at their routine, 10 years of age IQ assessment (mean age 123.8 months). The patients included 61 males and 30 females; 62 patients had undergone surgery and 29 had not.

RESULTS: The mean FSIQ for all types of craniosynostosis combined (96.2) fell within the average range for the general population. Some variation was evident across the different types of craniosynostosis: the SS group showed the highest FSIQs and a "normal" distribution of bandings; the other types had a higher proportion of FSIQs in the lower bandings. The data confirmed the finding that VIQ is greater than PIQ despite falling within the average range for intelligence, with a difference of 5.0 for all types of craniosynostosis combined (p = 0.001), 7.6 for the SS group (p = 0.001), and 6.9 for the unicoronal group (p = 0.029). This VIQ > PIQ effect was not found with multisuture craniosynostosis. The VIQ > PIQ discrepancy occurred regardless of whether the patient had undergone surgery and occurred more often in males than females. In the SS group and the bicoronal group, FSIQ (p = 0.036 and p = 0.046, respectively) and PIQ (p = 0.012 and p = 0.017, respectively), though not VIQ, were higher when surgery had been performed early.

CONCLUSIONS: The study confirms that at long-term follow-up, although children with nonsyndromic craniosynostosis fall within the normal range for intelligence, there is a VIQ > PIQ discrepancy above what would be expected in the normal population, which may be indicative of more subtle difficulties in achievement. This discrepancy is affected by type of craniosynostosis, sex, and age at time of surgery.