[Trigeminal neuralgia: interpretation of the results of the Dandy method of rhizotomy].

The patterns of sensory loss in 29 cases of Juxta pontine trigeminal rhizotomy are reported. The section of 70% of the portio major gave a similar impairment of tactile, thermal and pain sensibility in the facial area corresponding to the portio of the nerve section in all the patients. These findings do not support Jannetta and Rand's statement that partial to complete section of the porto major at the pons with complete preservation of the intermediate fibre does not affect the perception of light touch. The reported data suggest: 1--intermediate fibres are not mode specific fibres for light touch; 2--clear separation between thermoalgesic and tactile afferent rootlets does not exist in the trigeminal root; 3--saving the portio minor and the intermediate fibres ensures the preservation of perception of tactile, thermal and pain sensibility, thus avoiding postoperative painful anesthesia and keratitis.