Menigeal Extravasation, Efficacy of Botulinum Toxin or Triptans are not specific for Pathophysiology of Migraine only

Objective: Recently we discovered that neurogenic inflammation of dura (DNI) accompanies different types of pain in trigeminal region (Filipovic at al., J Neural Transm (Vienna). 2014;121:555–63). Here we investigated weather pain in trigeminal regions can be separated from DNI. Background: Neurogenic inflammation of meninges is accepted as important event in pathophysiology of migraine pai n. However, in rat DNI can be evoked by different forms of pain in trigeminal area. Such meningeal reaction accompanies selectively pain in trigeminal region only, and does not occur for example in crani al or spinal meninges after sciatic nerve injury). Such pain induced DNI is associated by activation of CGRP in dural nerves (Lackovic at al., Br J Pharmacol. 2016; 173:279–91). Design/Methods: All experiments were performed on male Wistar rats. After formalin injection, infraorbital nerve constriction injury, temporomandibular joint or maxillary sinuses inflammation in most models animal developed mechanical allodynia. Allodynia was tested by von Frey filaments and dural extravasati on was measured as colorimetric absorbance of Evans blue-plasma protein complexes. Dural infiltration with inflammatory cells was examined histologically. Results: Using different drugs like morphine, botulinum toxin or triptans we found that drugs that reduce pain (us ed in migraine therapy) reduce DNI as well. Studying time course of pain and DNI we found that durati on of DNI parallels duration of pain. Conclusions: Widely accepted understanding that neurogenic inflammation is an essential event in the pathophysiology of migraine pain, should be expanded. DNI apparently participates in the pathophysiology of various types of pain in trigeminal region. Thus it can be assumed that medications that reduce neurogenic inflammation should be effective in treatment of different headaches and other pain conditions in the trigeminal region. Study Supported by: Supported by Croatian National Science Foundation (no. IP-2014-09-4503; BrainTox; Z. Lackovic). Disclosure: Dr. Lackovic has nothing to disclose. Dr. Matak has nothing to disclose. Dr. Filipovic has nothing to disclose. Dr. Drinovac-Vlah has nothing to disclose. Dr. Bach-Rojecky has nothing to disclose.