Do you modify your target volume for treatment of trigeminal neuralgia confined to a single branch of CN V?

Short answer: NO.

Target is preferable to the cisternal segment and we have always cusped into the DREZ on the first treatment. Distal treatment nearer the Meckel's Cave and even beyond becomes more akin to a Rhizotomy and will have more likelihood of sensory loss and ultimately deafferentation pain...