Facial sensibility of patients with trigeminal neuralgias

Objectives Idiopathic trigeminal neuralgia (ITN) is an excruciating shock-like paroxysmal pain restricted to the trigeminal area of innervation, with discrete loss of sensibility (thermal, tactile and painful). Trigeminal postherpetic neuralgia (PHN) is a neuropathic pain at the trigeminal territory that persists after Herpes zoster infection, which also is associated to sensorial compromise. The objective of this study was to evaluate the somesthetic facial sensibility (pain, thermal and tactile) and to compare the findings between PHN and ITN. Methods 18 patients with PHN and 26 patients with ITN were diagnosed by the IASP criteria. They were evaluated with a systematic approach, which included mechanical, thermal (cold and warm) and painful stimuli. Results We found statistical significance at the ophthalmic branch of PHN in pain (p = 0.001), tactile (p = 0.002), cold (p = 0.016) and warm (p = 0.013); in ITN, the maxillary branch had higher threshold with pinpricks (p = 0.016) and the mandibular branch had higher tactile threshold. Conclusions The trigeminal area affected by the disease had the higher sensorial losses (ophthalmic branch in PHN and maxillary/mandibular branches in ITN). PHN patients had losses in large and small fibers; therefore, ITN patients had the losses mostly in large fibers, which support different peripheral neural mechanisms for these neuropathic diseases.