The Effect of Galcanezumab-gnlm on Post-Traumatic, Migrainous Headaches

The goal of this pilot, open-label clinical trial is to determine whether the addition of galcanezumab-gnlm to stable conventional headache treatment will reduce the number of monthly migraine days in participants who have experienced a traumatic brain injury and since developed post-traumatic, migrainous headaches. The main questions it aims to answer are: * if galcanezumab-gnlm is effective in reducing the frequency and severity of post-traumatic headaches with migraine features in study participants * if galcanezumab-gnlm reduces the impact of migraine on the daily life of the study participants Participants will complete five clinic visits over the study. Study participants will * complete a baseline visit including a HIT-6 Headache Impact Test score * complete a headache diary for 4 weeks to record the frequency and severity of migrainous headaches and other information * if determined to be eligible for the trial, undergo a brief physical exam and receive treatment with galcanezumab-gnlm, with a loading dose of 240mg delivered subcutaneously * receive two subcutaneous treatments with galcanezumab-gnlm (120mg) 4 weeks apart * complete a final study visit with a brief physical exam and HIT-6 Headache Impact Test score