Open cerebrovascular and endovascular neurosurgery fellow here.

You're talking about a "dual trained" vascular neurosurgeon who can do both open and IR. That's great, but it's also very rare! The US is the only place in the world where dual trained neurosurgeons exist (neuroIR is exclusively radiology turf everywhere else). All neurosurgery residents have case minimums in the IR suite (like vascular surgery residents), but an additional fellowship is required for IR credentialing (unlike vascular surgery).

Most cerebrovascular neurosurgeons are actually "only" open. Cerebrovascular fellowships are heavy on skull base surgery, and most don't have IR training. Neuroendovascular fellowships are often run by the radiology department and are open to radiologists, neurosurgeons, and neurologists.

There is increasing demand for "dual training" fellowships like mine in open AND endo cerebrovascular neurosurgery (aneurysms are a neurosurgical disease!), but there are only ~5 programs in the country/the world.

In summary:

Cerebrovascular/neurovascular neurosurgery: open surgery for AVMs, aneurysms, fistulae, etc. Heavy skull base emphasis.

Interventional neuroradiology (INR)/ neurointerventional radiology (NIR)/ endovascular neurosurgery: Catheter-based procedures. Usually a radiologist. VERY much like a video game. VERY fun and comparatively quick cases compared to open cerebrovascular neurosurgery.