Welcome back to the tasty morsels of critical care podcast.
Just to be clear up front we’re going to be talking about taking the lid off for stroke, NOT taking the lid off for TBI. I will get to TBI but they are really quite different topics.
This is not something that is done commonly but if you work in a neuro centre you will see it happen. We’re talking about the malignant MCA syndrome here. This is somewhat poorly defined but should reflect a large area of ischaemic tissue in the MCA distribution. The diagnosis of stroke here is not going to be subtle and expect at presentation a patient with a dense hemiplegia and almost definitely some early signs of stroke on CT that will rapidly develop. These people do not have malignant MCA syndrome at presentation (so this is not really an ED diagnosis) but large areas of ischaemic tissue over time tends to do what it does best – which is – swell. Consciousness will become impaired when it swells and remember that impaired consciousness is unusual in most strokes.
The swelling is where the real badness comes in. As Monroe and Kellie have taught us the skull is a fairly fixed box and once you’ve squeezed out the venous blood and the CSF then the pressure rises very fast and bits of brain try to squeeze through orifices amongst the dura they were never designed to cross. Death follows rapidly.
You can prevent this brain shifting, herniating phenomenon by taking the lid off and allowing the MCA territory of the parenchyma to expand out of the skull like bread dough rising of a tin during a nice long rest.
There is a surprisingly good evidence basis for this intervention with three trials all published within a few years of each other in what seemed to be a skull removing replay of any of the Football European Championships of recent years. Brief summaries follow:
- DESTINY 2007
- this was a German multicentre RCT including 30 pts
- there was a 90% v 50% survival favouring decompression
- DECIMAL 2007
- this was a French multicentre RCT including 38 pts
- they looked at the mRS as the primary outcome and found that those with decompression had much better neuro outcomes than those who didn’t but this was almost all due to the fact that those who didn’t get decompressed died in massive numbers
- as an example this trial found a 50% absolute risk reduction in mortality
- this was a dutch multicentre RCT including 64 pts. The difference here was that they allowed up to 4 days to have their surgery with prior trials only allowing up to 2 days
- they found that it still reduced mortality (again by ~50% absolute) but when done late did not seem to reduce long term morbidity
Who should you do this in? This is by no means a straight forward question but some useful numbers to take home would be
- <60 yrs old
- within 48 hrs of onset of the stroke
other things to consider include
- lives are clearly saved saved but almost everyone has moderate/severe disability following it
- the craniectomy must be at least as big as the margins of the stroke