Enigma of raised intracranial pressure in patients with complex craniosynostosis: The role of abnormal intracranial venous drainage. Taylor WJ, Hayward RD, Lasjaunias P, Britto JA, Thompson DNP, Jones BM, Evans RD. J Neurosurg 2001;94:377–385.

Abstract

Raised intracranial pressure (ICP) may complicate all forms of craniosynostosis. Several factors have been associated with increased ICP in patients with craniosynostosis, including craniocerebral dysproportion, hydrocephalus, the secondary effects of respiratory obstruction, and venous hypertension. In rare, but well-recognized instances, raised ICP can cause papilledema leading to secondary optic atrophy, reduced visual field and visual acuity, and even blindness. In this study, the authors investigated whether patterns of intracranial venous drainage in children with complex craniosynostosis associated with raised ICP were abnormal and, thus, could support the theory that venous hypertension is a major contributor to raised ICP in these patients, putting them at risk for impaired visual function. The authors analyzed the anatomy of intracranial venous drainage as demonstrated on 24 angiography studies from 23 patients, all of whom had either a craniosynostosis-related syndrome (18 patients) or a nonsyndromic multisutural synostosis (five patients). Twenty-one patients had evidence of raised ICP one to six weeks before undergoing angiography. Of the two remaining patients whose ICP monitoring was normal immediately before angiography, each had undergone two previous cranial vault expansion procedures. In 18 angiography studies, a 51% to 99% stenosis or no flow at all could be observed in the sigmoid-jugular sinus complex either bilaterally (11 patients) or unilaterally (seven patients). In 11 of these patients a florid collateral circulation through the stylomastoid emissary venous plexus was also seen. Comparison of two angiography studies performed in one patient with Crouzon syndrome demonstrated a progression of the abnormal venous anatomy. There was no obvious correlation between each patient’s baseline ICP and the degree of abnormality of their venous anatomy. The authors assert that in children with complex forms of craniosynostosis in whom other factors, such as hydrocephalus, are absent, abnormalities of venous drainage that particularly affect the sigmoid-jugular sinus complex produce a state of venous hypertension, which in turn, is responsible for the majority of cases of raised ICP. The incidence of these changes is unknown, but an analysis of the ages of the children in this study indicated that the period of particular vulnerability to the effects of venous hypertension lasts until the affected child is approximately six years old. After that age the collateral venous drainage through the stylomastoid plexus will likely become sufficient to allow ICP to normalize.—Nancy J. Newman