gms | German Medical Science

Trigeminal neuropathy after traumatic or surgical injury, destructive interventional procedures or infection in most cases is a pain syndrome due to partial deafferentation. While destructive procedures result in a worsening of symptoms, neuromodulation has been developed to reduce pain intensity by permanently implanted electrodes. A good effect of stimulation of the lateral thalamic area or the motor cortex was shown in small patient cohorts. Good to excellent analgetic effects have been achieved using percutaneous transforaminal electrode implantation into the gasserian ganglion or the retroganglionar roots. One of the problems associated with this approach is the high rate of dislocation (20-30%). In such cases the neurosurgeon has to decide whether the same approach or an alternative strategy of neuromodulation is to be chosen.

We report two cases of neuropathic facial pain, one posttraumatic with a 7-year history of transforaminal stimulation, another following surgical nerve trauma with a 3-month follow-up of successful transforaminal stimulation until dysfunction, loss of paraesthesia and increase of pain requiring opioid medication. Both patients reported a burning pain in the third trigeminal branch and increase on NRS from 4 to 10. In both cases the plain skull X-ray showed a correct electrode position. Because of the good clinical benefit prior to dysfunction, we decided to replace the stimulation electrode (Fa. Medtronic, DBS 3387) using the typical transforaminal approach.

In both cases a fracture of the electrode was found. The standardized approach and instrumentation for selective percutaneous thermolesions was implemented. The patients reported a good to excellent pain reduction and paraesthesia under improved telemetric stimulation parameters after successful replacement. One patient showed a good and stable analgetic effect, the other patient described a decrease of paraesthesia and analgesia after four weeks without demonstration of dislocation or lead fracture.

Reoperation for transforaminal electrode placement is likely to achieve successful neuromodulation. However, the revision of transforaminally-placed retro- or intraganglionar stimulation electrodes seems to have an inreased risk of dislocation or other dysfunction. In such cases we therefore consider early placement of electrodes through an open subtemporal extradural approach.