Sensory perception in patients with trigeminal neuralgia: effects of percutaneous retrogasserian glycerol rhizotomy.

We assessed thresholds for sensation of temperature and pressure and temporal summation of pain in the trigger area on the painful side and the contralateral nonpainful side in patients with trigeminal neuralgia previously treated with percutaneous retrogasserian glycerol rhizotomy (PRGR). Temperature and tactile thresholds were significantly increased on the painful side in both pain-free patients and patients with paroxysmal pain, but sensory loss was not more severe in patients with paroxysmal pain, except for increased warm thresholds. Abnormal temporal summation of pain (including progressive increase of pain intensity with radiation of pain and aftersensation) was present in the trigger area of patients with paroxysmal pain, but not in pain-free patients. Thus, relief of trigeminal neuralgia after PRGR involves normalization of abnormal temporal summation of pain, whereas sensory loss is less affected.