Thread by @walterfwiggins

Situation: You’re covering #Neurorad CT-guided biopsies and this case shows up on your list.

Older patient with recently diagnosed clear cell RCC. Lytic lesion in the upper sacrum seen on CT Abd/pelvis.

How do you approach it? #SpineIntervention
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Some options:
1. Anterolateral approach along the iliac bone.
👎 Long path, lots of bone to drill through.

2. Drill through the lateral aspect of the sacral arch to pass in between the thecal sac and the S1 nerve root.
😕 Durotomy risk 💦 and potential seeding 🫣

What else?
2/6

Using an 18-Ga as an introducer, you can FNA the lesion with a 22-Ga needle. But the S1 nerve root could still be an issue and there’s not a straight approach through the foramen.

But, we have two tricks up our sleeve that make this possible…
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First, we can use a 22-Ga spinal to inject some dilute contrast to highlight the nerve root so we know where it is for the duration.

Make sure it’s dilute (~33% in sterile saline) so you can still see your needle.

And chase it with some lidocaine to block the nerve.
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Next, we put a gentle curve on the end a fresh 22-Ga needle (NOT the one you used to inject contrast or lidocaine!) to slide medial to the nerve and into the lesion. Repeat as needed.

Note: RCCs are bloody and may require 3 or more passes to get a Dx.
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Finally, if chordoma is on your DDx, you’ll want to get your introducer as close to the lesion as possible to minimize seeding.
h/t @PeterGKranz

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