Slit-ventricle syndrome secondary to shunt-induced suture ossification

OBJECTIVE: To report five children with slit-ventricle syndrome who were found to have increased intracranial pressure despite functioning cerebrospinal fluid shunts. METHODS: Computed tomographic scans demonstrated erosion of the inner table of the cranium and sclerosis of the cranial sutures, particularly the coronal suture. Magnetic resonance imaging scans demonstrated no cerebrospinal fluid over the convexities. The patients were treated with cranial expansion operations that included removal of the sclerotic sutures, which were examined histologically. RESULTS: Postoperatively, symptoms resolved for all children. Sutures were abnormal and contained foci of cartilage and bone within abnormally arranged fibrous tissue. CONCLUSION: We postulate that chronic overdrainage of cerebrospinal fluid via shunts dampens the normal cerebral pressure waves; growth of the calvarium is thus understimulated, and this leads to ossification of the sutures, which become unable to expand to allow normal brain growth. Shunt-induced craniostenosis should be considered for children with symptoms of slit-ventricle syndrome for whom shunts are functional but intracranial pressure is increased. Cranial expansion operations may be more appropriate treatments than subtemporal decompressions for such children, given the diffuseness of the suture pathological features.