POSTERIOR-FOSSA REEXPLORATION FOR PERSISTENT OR RECURRENT TRIGEMINAL NEURALGIA OR HEMIFACIAL SPASM - SURGICAL FINDINGS AND THERAPEUTIC IMPLICATIONS

OBJECTIVE: To evaluate the surgical findings and subsequent therapeuti c implications of posterior fossa reexploration for persistent or recu rrent 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 failu re or recurrence after MVD: 23 for TN and 8 for HFS. Records were anal yzed retrospectively for evidence of vascular compression in primary a nd secondary operations, other pertinent intraoperative findings, intr aoperative therapeutic interventions, and postoperative results and co mplications. RESULTS: The previously placed polyvinyl alcohol foam (Iv alon sponge; Unipoint Industries, High Point, NC) or Teflon implant (T eflon felt; CR Bard, Inc., Bard Implants Division, Billerica, MA) was found to be in good position in 100% of the patients (31 of 31 patient s). New vascular compression from an arterial source was found in thre e patients during posterior fossa reexploration: one with TN and two w ith 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 reexplo rations. One bony source of compression was seen. No new compressive e lements 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 patien ts undergoing reexploration for persistent or recurrent HFS, six susta ined complications. CONCLUSION: Recurrent vascular compression was sel dom 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 a lternative in cases of recurrent TN when neurovascular compression is not identified. However, because of the relatively high incidence of c omplications associated with reexploration, we recommend of her ablati ve or medical treatments for most patients after failed MVD for TN or HFS.