The Blip on the MRI Scan: Cerebral Cavernous Malformations (by Danielle Steinbach)
Oct 04, 2025A neurosurgeon stands alone in a radiology room while their patient lies down, closed in on all sides by the mammoth magnets of an MRI machine. Hours later, the surgeon reviews the MRI scan – everything appears normal, except for one particularly dark spot that appears to be a hole in the gray matter of the brain. That small blip on the scan that seems so innocuous at first glance is a 1 in 500 occurrence. Specifically, it’s a cerebral cavernous malformation (CCM), a misplaced conglomerate of blood vessels with extremely thin walls.
As is generally true with a system as complex as the brain, even minor disturbances can create disproportionately devastating effects. Symptoms of CCMs range from relatively minor (i.e. headaches, inattention, vision issues) to severe events that may warrant a trip to the emergency room (i.e. seizures, sudden numbness, and strokes). However, despite the frightening possibilities that arise with CCMs, many afflicted individuals are asymptomatic and do not receive a diagnosis for decades into their life. In fact, a significant percent of cerebral cavernous malformations are only discovered when a patient receives an MRI for another purpose.
However, in cases where the CCM can be linked to a sudden onset of neurological symptoms, once discovered, the next step often involves considering surgical removal of the CCM. I say “considering” because brain surgery – as you may have already guessed – is rather risky business, and so the decision to operate can only be made if the harms prevented by the surgery outweigh the potential harms that could be caused by the surgery. In this case, surgeons rely on the Lawton-Kim Cavernous Malformation Grading System, which provides an eight point scale to assess the need for surgery. Using criteria such as the diameter of the CCM, age, and the CCM’s specific location in the brain, physicians assess whether surgical intervention is needed or if long-term monitoring would be preferred. Scores of two or less generally indicate that surgical intervention would be preferable for the long-term health of the patient.
For patients that decide to proceed with surgery, you might be wondering where one would even begin disentangling and resecting tiny blood vessels from the brain. Naturally, it begins with selecting a specific small region of the skull over which one can obtain access to the cerebral cavernous malformation. Using fMRI beforehand to localize the "hotspot" of blood flow in the CCM can be used to guide the decision of where to create a window-like opening in the skull for the procedure.
Now let’s assume the neurosurgeon has successfully opened this flap in the skull. They’re finally peering into the brain of their patient and they’re faced with masses of tissue and an interconnected network of delicate blood vessels. All you have as your window though is a small hole in the skull, so how does one then go about even finding the CCM, let alone removing it? It seems like trying to look into an entire room through a keyhole. Well, many neurosurgeons can verify the location of the CCM they’re targeting using intraoperative MRI to scan the brain in real-time and localize the mass of blood vessels. From there, the surgeon can finally gently and precisely excise the conglomerate of blood vessels while applying heat to stanch bleeding if necessary.
A few days later, the same neurosurgeon stands in the radiology room, looking at the MRI scan of the same patient. Where there was once a mass of vessels there now is a sleet of grey matter unobstructed.
– Danielle Steinbach
Sources:
https://neurosurgery.ucsf.edu/cerebral-cavernous-malformations
https://rarediseases.org/rare-diseases/cavernous-malformation/
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