ANA Discussion Forum
Pre-Treatment Options => Pre-Treatment Options => Topic started by: triplewave on October 18, 2017, 11:38:31 pm
I’m 30 years old and was recently diagnosed with a 25mm x 18mm x 18mm vestibular schwannoma.
The first sign of the problem was 2 separate episodes of sudden hearing loss 2 weeks apart, one lasting 3 days and the second lasting 6 days (treated with prednisone the 2nd time). My hearing is back to normal now (100% based on my latest audiogram), but I’ve started noticing a feeling of pressure on my skull on the side of the tumor and some tension in my neck. I don’t have any other symptoms.
Most of the surgeons I’ve spoken with have recommended retrosigmoid microsurgery, while another recommended radiosurgery (cyberknife). All have recommended against wait-and-watch.
At the moment I’m leaning towards radiosurgery. It appears to be effective on tumors larger than mine (https://www.ncbi.nlm.nih.gov/pubmed/21121793) and for young patients (https://www.ncbi.nlm.nih.gov/pubmed/19625908) and has a better rate of facial nerve and hearing preservation than microsurgery. I’m also very concerned about the cognitive decline that many have reported after microsurgery (http://www.anarchive.org/cognitive.htm; haven’t found any actual studies on this).
I’m somewhat concerned about the potential of radiation causing cancer eventually, but the likelihood seems significantly less than even the chance of death from microsurgery.
Is there anything I’m missing or should be thinking about? Any advice?
Welcome to the club that nobody wants to be a member of triplewave.
If you want to know more about the chance of a malignant transformation or radiation-induced new tumor, take a look at https://www.anausa.org/smf/index.php?topic=23320.msg979773231#msg979773231 and the referenced article.
I'm a big proponent of waiting to see evidence of sustained tumor growth before acting. If while observing there is significant growth or sustained increased in symptoms, it probably time to intervene. Use the time observing to find out more about this confusing disease.
The pressure on your skull sounds like something that an AN can cause, but the tension in your neck sounds unrelated. Good question to ask doctors.
You're doing well in researching this condition. It took me about 4 months of solid research to make head or tails of this.
Open Surgery: Most neurosurgeons will recommend retrosigmoid surgery. Most ENTs will recommend translabyrinthine approach. It's what they know.
Radiosurgery: "The available evidence indicates radiosurgery to be the best practice for solitary vestibular schwannomas up to 30 mm in cisternal diameter." http://bmjopen.bmj.com/content/bmjopen/3/2/e001345.full.pdf
Observation: At first, you may think that a 25mm tumor is too large for observation. Mine is larger than yours and I'm observing. Take a look at https://www.ncbi.nlm.nih.gov/pubmed/25120176 for more insights. My favorite author is Stangerup and two interesting papers are http://acusticusneurinom.dk/wp-content/uploads/2015/10/natural-history-of-vs.pdf and a more recent paper https://www.bhtinformatie.nl/pdf/ingrijpen.pdf .
ANs are slow growing tumors, growing on average only 1 mm per year. There is no need to rush into a decision. Talk to medical professionals (neurosurgeon, ENT, radiosurgeon) and keep up the research. It will serve you well.
Thanks ANSydney, very interesting articles.
I talked to several more surgeons this week. The general consensus is that radiosurgery is an option, but I should go with microsurgery. Now I'm on the fence since radiosurgery has a much greater chance of preserving my hearing, but microsurgery is more likely to control the tumor without additional treatment and doesn't carry the risk of radiation causing problems 15-50 years from now. I'm less concerned about facial nerve damage from microsurgery now - one of the top AN surgeons said there would be a <1% chance of permanent facial paralysis with his team.
I'm trying to answer several more questions now:
1. Is there any merit to the argument that we simply don’t know what effects radiation will have on my brain 15-50 years from now? Will I live my entire life thinking that every cognitive change/issue I experience is somehow a long term effect of the radiosurgery?
2. How much radiation exposure is the surrounding tissue actually receiving compared to common radiation sources (airplane flights, CT scans, etc)? Most doctors talk about a ~12Gy dose to the tumor, but I don't really know how to put the GK/CK dose to the surrounding tissue into the perspective of something like the XKCD radiation dose chart (xkcd.com/radiation (http://xkcd.com/radiation)).
3. IIUC, the facial and hearing nerves (and all nerves touching the tumor) would be irradiated at the same dose as the tumor since they lie on its surface, and they may become devascularized from the treatment. Does this have any effect on the function of the nerves, or is this just a problem in the case where I need surgery later?
4. One surgeon is concerned that given my young age, the tumor is likely to be growing more aggressively than average and thus the chance of radiosurgery killing the tumor less likely than the 92-93% average across all ages. Looking for research that would support this claim.
triplewave, if you're after hearign preservation, observation has the best outcome. From this paper ( https://pdfs.semanticscholar.org/2cef/abe8e8eef1ae32cab8bcf3c71dd75f53387c.pdf ), Gamma Knife accelerates hearing loss and watch and wait gives the best outcomes with regards to hearing. Notably:
"In the literature, to our knowledge, there have been no reports of the hearing preservation after 10 years or more after hearing preservation surgery or radiotherapy. In the present study [no active treatment], 95 patients had been observed for 10 years or more. According to the AAO classification, 46% maintained good hearing after 10 years or more compared with 45% using the WRS classification and 75% of patients with 100% speech discrimination at diagnosis.".
I don't know how your neurosurgeon puts the risk of permanent facial nerve damage at a low 1%. I was given the figure (for a slightly larger tumor) of 30% risk of damage. The paper http://bmjopen.bmj.com/content/bmjopen/3/2/e001345.full.pdf has the risk of facial nerve neuropathy at 10 to 30%, depending on size. And reports in papers are usually from the best centers with the best outcomes reported. Surgeons, as most people, overestimate their abilities, but 1% sounds off the scale. (Also, like most things, there is a scale. The House Brackmann scale defines facial nerve function from HB1 (perfect) to HB VI (total paralysis). Anything below HB III is quality of life affecting.)
Long term radiation effects are not known. If they were, more definitive options would be conveyed.
Radiotherapy normally targets 12 Gray at the 50% isodose level. That means that areas closer to the center get more radiation, the border gets 12 Gray and it drops off from there. For instance, you want to target a cochlear dose less than 4 Gray. Flying from coast-to-coast is 0.0003 Gray (and fractionated :-) ). If my calculating are correct, radiotherapy has a marginal dose thats about 3500 times greater than a CT, which in turn is about 500 times more than an x-ray.
My unprofessional opinion is that radiotherapy radiation doses are much more than from a CT, which is much more than from an x-ray, which is much more than naturally occurring. Keep in mind that one large dose is not the same as many small even if the radiatino dose is the same.
With regard to radiation the tumor and the collateral damage on the cochlear nerve and facial nerve, the facial nerve appears to be hardier. The cochlear nerve get more damage, but this can take years to show symptoms. After 10 years, it's very rare to still have useful hearing.
With regards to tumor growth there's only one way to find out - and that's a series of follow up MRIs. In the literature, age, tumor size and sex have no correlation with growth. The only prognostic factor is growth in the first year. Also, tumors grow more slowly with time (Table 1 from http://acusticusneurinom.dk/wp-content/uploads/2015/10/natural-history-of-vs.pdf ) and don't grow after 4 years from diagnosis. So unless you have rapid growth, or sustained significant growth, you've achieved what radiotherapy attempts to achieve.
Read the paper summaries in the reference section of https://www.bhtinformatie.nl/pdf/ingrijpen.pdf .