Is there an age cutoff at which you would recommend against radiosurgery for a schwannoma or trigeminal neuralgia in someone who is a good surgical candidate with no comorbidities?

Personally, I do not have a specific age cutoff, but do have a careful discussion about secondary malignancy risks in a younger patient.  With younger patients with schwannomas, one has to be careful about neurofibromatosis as there may be a higher risk of secondary malignancies from radiation.  With younger patients with trigeminal neuralgia, they may have multiple sclerosis that may make anesthesia risky. 

In a patient with no comorbidities, our tendency is to focus on surgical options, particularly those less than 40 years old.  That said, compared to 20 years ago, we know more and believe that the risk of secondary malignancies may be much less with radiosurgery compared to conventional forms of radiation due to its sharp dose fall off (minimizing low dose radiation spread surrounding the target) and the doses used which may result in more cell kill and less mutagenesis.

Ultimately, given the potential immediate risks of surgery, the patient may still opt for radiosurgery even after discussion of the risks of secondary malignancies.  Also, some schwannomas may be difficult to gross totally resect.  I would not shy away from treating these patients.