Recurrence of TN after a successful initial MVD can be attributed to different factors such as padding, deformation of the nerve due to adhesions, and continuous irritation by the offending vessel. A re-exploration can result in pain relief in the majority of patients 1).
The recurrence rate for TN attributable to veins is high. If pain recurs, it is likely to recur within 1 year after the initial operation. The most common cause of recurrence is the development and regrowth of new veins. Even fine new veins may cause pain recurrence; these veins may be located beneath the felt near the root entry zone or distally, near Meckel's cave. Because of the variable locations of vein recurrence, every effort must be made to identify recollateralized veins. Given the high rate of pain relief after a second operation, MVD remains the optimal treatment for the recurrence of TN attributable to vein regrowth 2).
In a retrospective investigation 7 patients operated on for recurrent trigeminal neuralgia via a suboccipital enlarged burr hole trepanation were evaluated. The intraoperative findings indicate that neo-compressive effects due to foreign material used during prior surgery are more important than adhesions around the nerve. Furthermore, the results of recurrent operations are encouraging as 6 of the 7 patients were painfree without additional neurological deficits 3).
Neither the Marseille study data nor literature data answer the 3 cardinal questions regarding repeat radiosurgery in recurrent trigeminal neuralgia: which patients to retreat, which target is optimal, and which dose to use 4).