Objective: To evaluate the surgical findings and subsequent therapeutic implications of posterior fossa reexploration for persistent or recurrent trigeminal neuralgia (TN) or hemifacial spasm (HFS) after failed microvascular decompression (MVD).
Methods: Between December 1975 and October 1996, the senior author performed 31 reexplorations for failure or recurrence after MVD: 23 for TN and 8 for HFS. Records were analyzed retrospectively for evidence of vascular compression in primary and secondary operations, other pertinent intraoperative findings, intraoperative therapeutic interventions, and postoperative results and complications.
Results: The previously placed polyvinyl alcohol foam (Ivalon sponge; Unipoint Industries, High Point, NC) or Teflon implant (Teflon felt; CR Bard, Inc., Bard Implants Division, Billerica, MA) was found to be in good position in 100% of the patients (31 of 31 patients). New vascular compression from an arterial source was found in three patients during posterior fossa reexploration: one with TN and two with HFS. New vascular compression from a venous source was observed in one patient with HFS. A scarred Ivalon sponge or Teflon implant with apparent mass effect on the nerve root was identified in seven reexplorations. One bony source of compression was seen. No new compressive elements or other sources of root irritation were appreciated in 61% of reexplorations. Partial sensory trigeminal rhizotomy was performed in 83% of reexplorations for persistent or recurrent TN. Of eight patients undergoing reexploration for persistent or recurrent HFS, six sustained complications.
Conclusion: Recurrent vascular compression was seldom identified during posterior fossa reexploration for failed MVD in patients with persistent or recurrent TN or HFS. The previously placed Ivalon sponge or Teflon implant was consistently found to be in good position. Partial sensory trigeminal rhizotomy is an often effective alternative in cases of recurrent TN when neurovascular compression is not identified. However, because of the relatively high incidence of complications associated with reexploration, we recommend other ablative or medical treatments for most patients after failed MVD for TN or HFS.