Figure 12.

Intrathecal contrast-enhanced MRI in one subject with IIH provides evidence for a glymphatic system in patients with IIH. Intrathecal injection of the MRI contrast agent gadobutrol (Gadovist^tm, Bayer Pharma AG, Berlin, Germany) in a dose 0.5 mmol, serves as a CSF tracer molecule. Gadobutrol has a molecular size of about 604 Da and is highly hydrophilic, making it suitable for transport within the CSF. After arriving to the subarachnoid CSF, the tracer is contained outside the blood vessels since it does not pass the BBB. Using FreeSurfer, tracer in CSF spaces is subtracted, only showing enrichment of tracer in brain parenchyma over time in this IIH patient responding to shunt surgery. The tracer enriched in the interhemispheric fissure and Sylvian fissure and medial temporal where the large vessels resides anterior middle cerebral and posterior cerebral arteries, respectively. Moreover, the tracer enriched in a centripetal fashion; at 24 h the entire brain had enriched with tracer that lasted at 48 h. In vivo evidence for impaired glymphatic function in IIH has been given before (Eide et al., 2021b). Illustration: Lars Magnus Valnes, Department of neurosurgery, Oslo university hospital, Oslo, Norway.