Kristen W. Yeom
Hydrocephalus is a common neurosurgical condition that often requires radiologist input. Some cases are pretty straightforward. For example, a patient comes in with headaches or altered mental status with newly enlarged vents, periventricular edema, and has hemorrhage or a big tumor causing obstruction. Or, there might be prior comparison in a shunted patient that shows an obvious interval change. Oftentimes, however, we’re not so lucky. What makes it even trickier is that many kids and older adults in whom hydrocephalus is more prevalent can present with large-looking ventricles for all sorts of reasons—developmental delay, metabolic or genetic disorders, prior medical therapy, and chronic volume loss, to name a few. To make matters worse, literature tells us that high intracranial pressure or CSF volume doesn’t always match up with the ventricle size. Is there anything left for us except to say “correlate clinically” in these tough cases?
Some animal and clinical studies have suggested that perfusion might be reduced in elevated intracranial pressure states. Based on this, we surmised that cerebral perfusion using arterial spin-labeling (ASL) might be reduced in acute, uncompensated hydrocephalus, and improved after surgically mediated alleviation. This hypothesis was supported by our data, and we were happy to see that MRI can provide relevant physiologic information associated with hydrocephalus, and importantly, without requiring contrast or radiation—an added bonus, especially in kids.