Tuesday, April 3, 2012

By the Numbers - Surgical Risk Presented

My favorite way to play the odds in Vegas!
Armed with some fresh data, here is an analysis of what has been presented by my neurosurgeon in terms of surgical outcomes for the removal of my brainstem cavernous malformation...

Doing surgery now:
  • 10-15% chance of new permanent neurological deficit, could be as simple as losing feeling in finger, or losing ability to move on left side of body.
  • 93% chance of successful resection, or 7% chance of failure leading to likely bleeds in the future as its not fully removed
Doing surgery after a hemorrhage external to the cavernous malformation that also creates a large opening in front of brainstem (a lot of maybes):
  • 8-12% change of new permanent neurological deficit
  • 95% chance of successful resection, or 5% chance of failure
Its worth acknowledging that these generic odds are extrapolated from the clinical experience of an expert but they are not necessarily my odds.  But look the world isn't perfect and its what I have to work with.

In my review of case studies and discussion with those that have had surgery, I will for simplicity say that having a failure during the surgery is a bad outcome on par with acquiring a new deficit.  Its a simplification but what is clear is that any brain surgery itself is a traumatic event and requires lots of rehabilitation (many months or more in some cases), and unknown consequences.  Some people even have stokes during their brain surgery or as a result of!

So to boil this down and oversimplify:
  • Now: 17-22% chance of poor surgical outcome (22% pessimistic)
  • Ideal: 13-17% chance of poor surgical outcome (17% pessimistic)
So WAIT!  you must be saying.  Because I know right the odds really don't get that much better, (20% relatively fewer poor outcomes).  That is why a substantial part of this analysis is how I am doing now, and that I should really be much worse off than I am before doing this makes sense, so that the risk/benefit analysis starts to play out better.   Perhaps getting further damaged from a bad surgical outcome when I am already more damaged makes good sense on the trade-offs.  As my neurosurgeon put elegantly in a doctor's note recently, I am currently "neurologically intact".

So playing this out... one meta study (a study of studies) seems to indicate that from brainstem cavernous malformation, the risk of a new hemorrhage is about 20-30% annually after the first clinical event and decreases over time especially after the first 2-3 years.  In one study the progression went like this for cavernous malformations generally (not just brainstem): 20% year-1, 13% year-2, 12% year-3, 5% year-4 and 5% year-5. 

Data on getting new problems from these bleeds is scant, but seems about 1/5-1/3 of these can result in a new permanent neurological deficit, so we might be looking at 4-10% annual chance initially of acquiring a new permanent deficit from the CM, and declining from there if it stabilizes, and a series of years might look like 7%, 4%, 4%, 2%, 2%, ... -- on acquiring a new permanent deficit from a new bleed.

So the trick here seems to pray for the best, hope it stabilizes, help it stabilize, etc.  No?

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