Ho-ho-ho! Gather ’round, my curious elves, for I have a tale to tell that’s as intriguing as the mystery of how I fit all those toys into my sleigh! This story unfolds in the hallowed halls of medicine, where brainy boffins have been tinkering with a technique as magical as my own North Pole workshop. It’s called microdialysis, and it’s used to peek into the interstitial fluid of the central nervous system, much like I peek into my list to see who’s been naughty or nice.

Now, our tale centers on those naughty brain tumors called gliomas, which are about as unwelcome as a lump of coal in a stocking. These tumors are usually only accessible when the surgeons are at work, much like how I can only deliver presents when I shimmy down the chimney. But these clever clinicians have rarely analyzed gliomas using the interstitial fluid collected via microdialysis… until now!

With a twinkle in their eye, they got special permission to use high molecular weight catheters, or HMW for short (100 kDa, no less!), and a variable flow rate pump that’s as adjustable as my reindeer’s speed. This gear allowed them to perform microdialysis at flow rates that are just right for an intra-operative setting, which is doctor-speak for “while the surgery is happening.”

During this festive experiment, they performed intra-operative HMW microdialysis on 15 glioma resections in fourteen patients, exploring three different brain regions in each. It was like checking the list thrice! They then analyzed the microdialysates with a technique as sophisticated as my navigation system: ultra-performance liquid chromatography tandem mass spectrometry.

But, oh, what fun it is to ride in a one-horse open sleigh and discover that the type of perfusate (that’s the fluid they use in microdialysis) can affect the metabolites they’re studying. They even found that delivering lactate directly to the brain can cause local metabolic changes, hinting at the possibility of testing drugs right there in the operating room, much like I test toys in my workshop.

And would you believe it? They could detect drugs like levetiracetam and caffeine from just a 10-minute sample of this microdialysis magic. It’s like finding out which cookies you’ve left out for me in record time!

So, as we wrap up this story (and I’m quite good at wrapping, you know), let’s remember that intra-operative HMW microdialysis can indeed be used to sample the bustling CNS microenvironment during surgery. But, just as I must consider the width of chimneys and the appetite of reindeer, these doctors must ponder variables like perfusate type.

And with that, my dear elves, our narrative comes to a close. May your days be merry and bright, and may all your microdialysis be just right! Trial registration NCT04047264.