Recurrent trigeminal cistern glycerol injections for tic douloureux.

Fourteen of 60 cases (23%) of trigeminal neuralgia underwent a repeat trigeminal cistern glycerol injection for recurrent pain. The mean time to recurrence was 14 months and the mean follow-up time following the last injection 10 months. Measurement of trigeminal cistern volume at the first and second procedure with metrizamide showed a significant decrease in the cistern volume from 0.38 ml to 0.29 ml. Clumping of nerve roots indicative of arachnoiditis was observed in 4 cases. In 2 further cases difficulty was encountered in emptying the cistern of metrizamide. After the repeat injection 2 patients developed painful dysethesia. Six patients showed either new or increased facial sensory deficits. These findings may indicate trigeminal cistern arachnoiditis. The possibility of deafferentation pain developing after trigeminal glycerol rhizolysis should prompt caution in the use of this technique in the younger patient.