Chita; Final Hopkins Visit Prior to AVM Surgery

Today we were scheduled to meet with two of Christopher’s neurosurgeons.  First we met with Dr. Mari Groves, his pedi spinal doc and Chiari specialist.  Despite what we’ve been told by the vascular team, she isn’t ready to discuss treatment for his Chiari I malformation in any way.  She feels that his upcoming microsurgical dissection and craniotomy to remove his AVM is too huge and major a surgery to even contemplate the next steps.  When we pressed her, she told us that she wouldn’t even consider surgery for 6-12 months.  Months!!!

Christopher crumpled in his chair.  It was like he’d been sucker-punched in the gut.  

We explained how severe his headaches are, how attempting to play for a few days leaves him with hideous headaches for days, how his activity is so limited it goes against everything I’ve ever learned in 13 years of parenting, and all the science espoused by the American Academy of Pediatrics about the importance of 1-2 hours of daily exercise for all children.  We also explained that Dr. Ahn had told us his brain would, of course, need to fully revascularize before a second surgery, and Dr. Tamargo would have the final word, but that he anticipated 3 months between surgeries.  Dr. Groves relented a bit and said we could do a follow-up in 3-6 months to see where things stand.  But she reiterated that she doesn’t want us to think about the Chiari at all, but to focus on the AVM surgery because it could actually kill him if it ruptures, it’s extremely major surgery, and we just can’t think beyond it right now.

The last I spoke with our pediatrician, he told me that after AVM surgery, the options for pain control open up a lot more and we can try sending Christopher to an anesthesiologist pain specialist.  So I switched tactics and asked her what she thought of that course of action to get him through to the next surgery.  Her response was a vague sort of, well, we can try it, but nothing controls the pain of a Chiari headache.

I’m not sure I’ve ever been so upset in my life.  We’ve spent a lot of time the last 3 weeks trying to make this first surgery a positive experience.  We’ve talked about how AVMs often cause headaches and motion sickness, so it might not “just” be a pre-requisite to the Chiari decompression (because, let’s face it, the daily pain he experiences is more pressing to my 9 year old than the chance of the AVM rupturing inside his brain, although he’s fully aware of its repercussions).  We’re organizing a brain party for him and his friends the weekend before surgery so that we can celebrate this first step to his recovery.  As he’s asked questions about different aspects of surgery, I’ve tried to frame them as positively as possible:  Will they use staples?  Maybe.  But if they do, it’s because they’re stronger than stitches and they want you to have the smallest, straightest scar possible.  

I feel like she undid 3 weeks of pep talks, party planning, Q&A sessions, and meditation in 10 minutes.

Thank goodness, our appointment with Dr. Tamargo went much better.  He’s a portly, grandfatherly type, and instead of getting straight to business, he started at the beginning, with our new patient questionnaire.  Then he asked, “How did you get to here?  What got Christopher to this diagnosis?  What started this path?”  And he listened, while gave the 10 minute version of Christopher’s story.  Then he excused himself so that he could speak with Dr. Groves.  When Dr. Tamargo came back, he said that he believes the main source of Christopher’s pain is the Chiari, and he feels it’s 50/50 which gets treated first, so he had gone to ask Dr. Groves if she wouldn’t do that surgery first.  

She declined.

With that out of the way, he explained his 31 years of experience, how he came to be the guy at Johns Hopkins with the most experience at handling AVMs, and why he thinks Christopher makes a great surgical candidate.  Since we hadn’t actually seen the results of his angiogram, Dr. Tamargo was happy to guide us through the images.

Image 1--View of the AVM and its feeders in Christopher's angiogram.

Image 2--Close-up of the AVM.  It really is just a tangled web.

His Spetzler-Martin score is a 2, surgical excision is generally considered only if the grading is no higher than a 3 of the 5 possible points.  The AVM is larger than we had initially anticipated, 2.6cm on its longest axis, but still well below the 3cc cut-off to be considered small.  It has only superficial veinous drainage.  It doesn’t have an aneurism hiding inside it.  It is centered on his central sulcus, which makes it prime real estate, although the sensory strip is less critical than the motor strip, but Dr. Tamargo assures us he’s removed AVMs from just the motor strip before.  Dr. Ahn had told us that the nidus, or core of the AVM, is actually just behind the central sulcus in the sensory strip, with just a few vessels snaking into the motor strip region responsible for movement of his left leg.  While there is always a non-zero chance of death or permanent neurological deficit, in 31 years, he’s never had either.  There is a greater risk that Christopher will wake up with weakness in his left leg, or even his whole left side, but it will almost certainly be temporary.  Nearly all AVM patients come in with headaches because that’s usually what leads to brain MRI and the initial diagnosis.  Half of all AVM patients report their headaches ceasing after surgery, but there’s no way to know ahead of time which half Christopher will fall into.  So we’ll hope.

Figure 1--This image is known as the homunculus diagram of motor and sensory control in the brain.  Notice that small regions like the tongue and lips take up far greater brain space than the entire trunk due to the highly detailed and sophisticated muscle movement necessary for speech.  Image Courtesy of the Brain Book, p. 23.

The surgery itself is predicted to take 6 hours.  With an angiogram before to determine exactly where to open him up, an angiogram after to make sure the AVM is completely gone, and the time to prep him for surgery, we’re looking at 8+ hours.  The operating room has been booked for Dr. Ahn and Dr. Tamargo’s use for Christopher for the entire day.  Recovery is likely to be one night in Neurological Intensive Care, 2-3 days on the Peds floor before he comes home.  Dr. Tamargo wants us to be prepared for him to need 6 weeks before he can return to work/school.

After surgery, Dr. Tamargo says that if everything goes perfectly, he’s prepared to clear Christopher for Chiari surgery at the 6 week post-op appointment.  Again, I told him that while Dr. Ahn deferred to Tamargo as the expert, he was thinking it would take 3 months.  Dr. Tamargo smiled and said that was likely a more realistic scenario, but he really was prepared to clear him earlier and move up the normal MRI schedule if necessary to make that happen.

And then we went to Kona Grill for sushi.  And edamame because Christopher loves edamame.  And passion fruit creme brulee, which was to die for.

Now, he’s in a pretty good mood.  He likes Dr. Tamargo, he trusts Dr. Tamargo, he’s excited for the AVM surgery.  I am in complete agreement.  But I’m still a ball of nerves because of the earlier appointment.

Krasnoyarsk; What is an AVM, anyway?

As expected, Dr. Ahn told us Christopher needed a cerebral angiogram to know for certain what kind of tangle was in his brain.  But first he showed us what they were seeing in his MRI and what it meant.  In the very top layer of his brain, you see a few tiny black circles in the middle, just to the left, kind of like swiss cheese.  The next layer down—nothing.  

Image 1--View of the AVM in the top layer of Christopher's brain.  I added the labels.  Note that since the AVM is located in the right side of his brain, any deficits would occur on the left side of his body.  Also note that it is straddling the central sulcus, but in this view, appears to mostly be located in the pre-central gyrus, aka, the motor strip.

Dr. Ahn said those black circles could mean one of three things:  

1. A benign tangle of blood vessels that will never cause harm.
2. A true, but mild, arteriovenous malformation (AVM), where the arteries are hooked up directly to the veins without any intervening capillaries.  They’d monitor it yearly.
3. A true AVM that is deemed dangerous enough to remove.

Why are AVMs dangerous?  First, veins aren’t intended to take the pulsile flow of an artery, but since the blood flow slows WAAAAY down in the capillary beds, that isn’t an issue in normally wired blood vessels.  Second, the arteries in an AVM are missing a structural layer that causes the whole thing to wind up like a tangled ball of yarn.  

 Figure 1--Okay, so this is two figures I pulled off the braingletangle blog, but I like the visualization of an AVM compared to a normal artery--capillary bed--vein connection.

He also felt, based on what he saw on the MRI image of Christopher’s brain, that an AVM diagnosis would be physically inoperable and would require gamma knife surgery to remove.  Why?  Because they thought his AVM is in an area of the brain called the motor strip.  When you decide you want to move one of your skeletal muscles, the motor strip is responsible for sending that message down your spinal cord to the muscles required.  In the world of vascular neurosurgeons, it makes it “eloquent tissue”; to the layman, it’s “prime real estate”.  Just behind the motor strip is the sensory strip, which, as the name implies, is responsible for receiving the sensory input from various areas of the body.  Where the regions of the motor strip learn early which parts of the body to control and display little plasticity for taking on new roles later in life, the sensory strip is much more flexible.  Lying immediately between the two regions is a line called the central sulcus.

Figure 2--The pre-central gyrus, also known as the primary motor cortex or motor strip, is the area just in front of the central sulcus in this diagram.  The post-central gyrus, also known as the primary somatosensory cortex or sensory strip, is located immediately behind the central sulcus.  Image Courtesy of The Aneurysm and AVM Foundation.

Christopher's biggest concern about the angiogram, as usual, was whether or not he’d need an IV.  As soon as he heard the words “gamma irradiation”, however, he was all atwitter with questions about the nature and safety of the therapy.  Luckily, Dr. Ahn is a pediatric neurosurgeon and appeared more than happy to answer those questions.  He was also ready to explain how gamma irradiation shreds the DNA inside the targeted tissues, but since I spent several years in graduate school studying the DNA damage repair cycles, we were able to focus on Christopher’s questions.

With that information, we chose the first available date for a cerebral angiogram and awaited our arrival at the next station.