× Key messages Background Findings Perspectives Expert commentary

Expert commentary

by Andrew Russo, PhD

There are several hidden jewels in this mouse study that will be relevant to clinical practice. First, the study provides clues to answer the puzzling question of why are post-traumatic headaches (PTHs) so similar to migraine? The migraine connection may lie in the finding that the neuropeptide CGRP plays a role in at least one symptom of PTH, similar to its well-established roles in migraine. Indeed, in addition to pain, a common feature of PTH is sensory hypersensitivity, which is a hallmark of migraine. The tactile hypersensitivity tools used in this study are directly translatable to quantitative sensory testing in the clinic. Second, by comparing two different types of traumatic brain injury (TBI), the authors drive home the point that not all TBIs are equal, which may help explain why PTHs can be chronic, but more often become episodic after the injury. In this regard, the finding that multiple TBIs spread out over several days is actually worse than multiple TBIs on the same day or a single TBI event suggests that we may want to reconsider how long between TBI events is actually safe. Third, most importantly, even after the hypersensitivity subsided, mice with a mild concussion-like TBI were still sensitive for over 100 days to two migraine triggers (CGRP and the nitric oxide donor SNP). These triggers re-initiated tactile hypersensitivity in the TBI mice, but not in controls that had not had any TBIs. This suggests that TBI patients could go headache free until unexpectedly exposed to a trigger that would not have affected them before their TBI. This sensitivity to a trigger is very reminiscent of human studies showing these same triggers (CGRP and SNP) cause migraines only in migraine patients, while control subjects only get a mild headache without migraine symptoms. Therefore, as a good place to start long-term management of their headaches, TBI patients should keep a diary to identify their individual triggers, similar to those kept by migraine patients. Finally, from a patient’s perspective the most meaningful result of this study is that by showing a causative role of CGRP in a PTH symptom, this strongly supports the use of the new CGRP therapeutic drugs to treat headaches after TBI.

0:0