Value of preoperative imaging in the diagnostics of isolated metopic suture synostosis: a risk-benefit analysis.

Radiographic evaluation including plain radiographies and computed tomographic (CT) scans are considered as a necessary tool for diagnosis of craniosynostosis. As recently concerns about harmful effects of ionising radiation in children have been raised, some authors have suggested the use of magnetic resonance imaging (MRI) as a helpful alternative in preoperative imaging of patients with isolated metopic synostosis. Besides confirming the diagnosis of trigonocephaly, MRI is the superior technique for the evaluation of underlying brain anomalies. However, if the benefit of preoperative imaging justifies possible side effects is still discussed controversially. Hence, this study investigated the value of preoperative imaging for the diagnosis of isolated synostosis of the metopic suture compared to a sole clinical examination. In a series of 63 cases with isolated metopic craniosynostosis operated at the Department of Oral and Maxillofacial Surgery, 48 (76.2%) patients received additional radiography or MRI investigation, while in 15 (23.8%) patients the diagnosis was based on clinical examinations only. In all patients, diagnosis was confirmed intra-operatively by a fused metopic suture. CT scans with three-dimensional reconstruction (12.5%) or plain radiographs (39.6%) did not provide any additional benefit for the diagnosis or the surgical treatment. In 23 patients (47.9%), MRI showed the typical soft-tissue alterations like triangular brain deformation in the frontal area. Besides these findings, no brain or other underlying anomalies were diagnosed which had required any additional treatment. The incidence of underlying brain abnormalities in isolated metopic synostosis seemed not to be different from that of the general population. As the characteristic clinical manifestations were sufficient for an accurate diagnosis of isolated metopic synostosis, and with respect to the biological effects of ionising radiation and risks of sedation especially in infants, preoperative imaging should be reduced to a minimum.