Global rostral midbrain syndrome complicating low-pressure state following ventriculoperitoneal shunting for aqueduct stenosis

Global rostral midbrain syndrome (GRMS) is a rare, severe complication of cerebrospinal fluid (CSF) shunting where midbrain, callosal and basal ganglia damage follows over- or under-CSF drainage. A 54-year-old woman developed subacute diplopia and cognitive impairment 10 years after ventriculoperitoneal-shunt surgery for aqueduct stenosis. Clinically, she had Parinaud syndrome and cognitive impairment. MR scan of the brain showed slit-like lateral ventricles with T2 hyperintensities around the shunt catheter and the corpus callosum. Shunt setting changes led to partial symptomatic improvement and resolution of slit ventricles, but the callosal changes persisted with ongoing mild visual and cognitive impairment. The presumed mechanism of GRMS is CSF overdrainage causing low supratentorial pressure with a transtentorial pressure gradient, leading to vertical displacement of the midbrain and subsequent mechanical stress. As antisiphon devices are now routinely combined with programmable shunts in the UK to optimise intracranial pressure without CSF overdrainage, GRMS should now become less common.