Whats a large M4? The point is, as we have emphasized, that defining what M1/2/3/4 is can be tricky. Even M1 ranges from nonexistent (duplicated/accessory MCA) to infinite (no true M1 bifurcation). In-between are bi- tri- quadro- and pentafurcations we’ve shown on the MCA page. We have argued that assessments should be based on volume of tissue at risk, not vessel size — large, medium, and small volume targets, not large, medium, and small vessel targets.
Fine, fine, whatever… Lets say M2 and M3 are hard to define. But M4 should be easy — whatever is on the surface is M4. Well, not so fast — even by that definition, some M4s are bigger than others. Take a look
Standard issue proximal occlusion
Post solitaire-Sofia6 thrombectomy — distal embolus (arrows)
Looks pretty distal — a proximal M4 occlusion if M4 is defined as convexity surface vessel … Usually we try to aspirate these first with an 027 catheter. However, this picture was made with a Marksman — an 027 – which is too small for this size vessel/embolus. To succeed in distal aspiration, the catheter should usually be the same diameter as the vessel.
Lateral views below
Its a decent-sized wedge — probably around 25 mls — and likely to be eloquent
Access as follows — important to get zoom far enough into the clot, and have sofia 6 as far as safely possible to help.
The technique is to aspirate on both zoom and sofia while sofia is occlusive — in this case pulling back zoom brought sofia up into superior division where it wedged
Relative positions of zoom and occlusion
Post — there were no less than 3 branches (arrows) supplied by this occluded branch — not the single M4 one might expect on the surface
Magnified view of recanalized vessels (three branches marked by dashed arrows now). Position of zoom by solid arrow.
See what we are talking about — not all M4s are created equal, size-wise as well as location-wise… Did we have to go for it — definitely yes as far as we felt, considering the eloquence of territory