Primary delayed onset craniosynostosis is a rarely reported phenomenon. The unique case of a 2-year-old boy who had computed tomography (CT) scans performed 20 months apart demonstrating the post-gestational development of sagittal suture craniosynostosis is presented. The otherwise healthy male initially presented to the emergency department at age 7 months with soft tissue swelling over his left parietal region secondary to a fall. A CT scan revealed a possible left parietal skull fracture without intracranial pathology and patent cranial sutures with a normocephalic calvarial configuration. Twenty months later, his paediatrician referred the boy to the craniofacial service for evaluation of progressive dolichocephaly. A new CT scan showed complete fusion of the sagittal suture with resultant biparietal narrowing, frontal bossing, and occipital prominence. The patient subsequently underwent uncomplicated frontoparietal craniotomy with calvarial vault reconstruction. Prior reports in the literature of cases of non-syndromic primary delayed onset craniosynostosis all lack ‘pre-synostosis’ CT imaging that proves post-birth patency of the cranial sutures. This case report documents CT demonstrating true primary delayed onset craniosynostosis.
The incidence of isolated non-syndromic craniosynostosis in the newborn population has been estimated to be approximately 0.6 in 1000 live births. The underlying pathogenesis of premature suture fusion is believed to involve a combination of mechanical and molecular constraints that impact the developing skull in the prenatal period. The resultant calvarial deformity, although sometimes subtle, is therefore generally noted at birth and worsens over time if untreated. Numerous studies in the craniofacial and neurosurgical literature have described the natural history and surgical management of non-syndromic single suture craniosynostosis. Among these publications, a small subset of cases have been presented as delayed onset or post-gestational. Typically, the diagnosis in such patients has been made later in childhood following a period of apparently unremarkable skull development. The diagnosis may also be made in the setting of new secondary synostosis of a previously unaffected suture in patients who have undergone prior craniosynostosis repair. Multiple reports have also reported post-gestational synostosis following shunting for the treatment of hydrocephalus.
In order to meet the true definition of primary delayed onset craniosynostosis, clear radiographic evidence of normal postnatal calvarial configuration and patent sutures must be present, along with subsequent imaging demonstrating premature suture fusion and the associated skull deformity. Such a case does not appear to have been reported in the paediatric craniofacial or neurosurgical literature. The case of a 2-year-old boy who had a normal computed tomography (CT) scan of the head at 7 months of age with subsequent development of sagittal craniosynostosis is presented. This was confirmed on CT performed 20 months later, and he underwent uncomplicated cranial vault reconstruction. The presenting symptoms, imaging findings, operative details, and theories regarding the aetiology of primary delayed onset craniosynostosis are discussed.
History and presentation
A previously healthy 7-month-old boy presented to the emergency room 24 h after he fell from standing and hit his head at daycare. There was no loss of consciousness, seizure, headache, or emesis. However, his mother brought him to the hospital the next morning when she observed progressive scalp swelling. The patient had no complaints. On physical examination he had a left parietal soft tissue swelling with no focal neurological deficits. His cranium was otherwise normocephalic. Non-contrast CT with three-dimensional (3D) reconstructions was performed, demonstrating a possible linear non-depressed left parietal skull fracture versus a non-pathological vascular groove. There was no intra- or extra-axial haemorrhage and the cranial sutures were patent ( Figs. 1–3 ). The patient was discharged home from the emergency room. Re-examination 3 weeks later showed the patient to have recovered fully from his minor head injury.
Approximately 20 months later, the same patient was referred back to the neurosurgical and craniofacial surgical services for evaluation of progressively elongated head shape, as observed by his paediatrician. He had achieved appropriate developmental milestones and was otherwise in good health. The paediatrician ordered a repeat non-contrast CT scan of the head with 3D reconstructions. The scan demonstrated complete fusion of the sagittal suture. This was a new finding when compared to his prior imaging and was therefore consistent with delayed onset craniosynostosis ( Figs. 4–7 ). No intracranial pathology was noted and the patient’s physical examination revealed frontal bossing, ridging of both the metopic and the anterior sagittal suture, biparietal narrowing, and mild occipital prominence. 3D laser scanning for craniometric measurements showed an abnormally low cephalic ratio of 0.70. He had no current signs or symptoms of intracranial hypertension. The parents were informed of the diagnosis as well as the likelihood of a progressive deformity and the risk of possible raised intracranial pressure in the future without intervention. After thorough discussion of all treatment options (including no intervention) and the risks, benefits, and alternatives, the family agreed with the recommendation for surgical management.