This patient with persistent, migraine-like post-traumatic headache only received structured pain management after 30 years of treatment with analgesics as needed. Unfortunately, this is not uncommon, as post-traumatic headache remains an entity that is challenging to treat . Often, the referral to a pain management specialist constitutes a hurdle that prevents patients from receiving optimal treatment. Only now, an attentive pharmacist who noticed the patients extensive need of painkillers, suggested an evaluation by a pain specialist.
Although amitriptyline treatment was effective and the patient was able to drastically reduce his extensive use of analgesics, it transpired not to be the optimal treatment when the patient developed RLS. Although it remains unclear whether the RLS was actually induced by amitriptyline or was a late effect of the injury, discontinuation of treatment was advisable due to a substantial risk of worsening the RLS symptoms .
Erenumab rapidly and effectively reduced the number of headache days per month to 2–3, without the need for additional t-SNS application. This was the best outcome the patient had experienced since his accident over 30 years ago and it substantially improved his psychosocial conditions and life circumstances. Only then did he realize that he had been rather limited by the constant fear of provoking headache attacks that had accompanied him through his entire adult life.
Erenumab is a fully human monoclonal antibody directed specifically against the CGRP receptor. Unlike amitriptyline, it does not interfere with serotonin or histamine pathways and thus there is no reason for it to influence the existing RLS.
Regarding his 30-year pain history, we expect that this patient will require long-term erenumab treatment. The proven long-term efficacy and excellent safety profile over 5 years so far is thus reassuring . Importantly, erenumab has a low interaction potential which is favourable considering the patient’s comedication.
Despite a very similar phenotype, migraine-like post-traumatic headache and primary migraine were shown to be associated with differences in brain structure in a recent study based on magnetic resonance imaging suggesting differences in pathophysiology . However, this does not exclude a common role for CGRP as both entities are supposedly multifactorial processes. Recent preclinical studies of mild traumatic brain injury, using rat models, showed that treatment with an anti-CGRP monoclonal antibody following concussion ameliorated pain-related behaviour and hypersensitivity in the acute phase [5, 6]. However, delayed administration of the CGRP inhibitor appeared to be ineffective in preventing persistent post-traumatic headaches in rodents which led the authors to the conclusion that GCRP was mainly involved in the development of central sensitization after the event and was thus associated with promoting (but not sustaining) persistent post-traumatic headache .
In a recent report, impressive results were obtained with erenumab in 7 severely symptomatic patients with acute migraine-like post-traumatic headache secondary to mild traumatic head injury. The patients started treatment between 4 and 11 weeks after the trauma and all achieved a ≥ 95% reduction in headache days per month .
Furthermore, Ashina et al. conducted a single-arm, open label study with erenumab for the prevention of persistent PTH attributed to mild traumatic brain injury. During the 12-week treatment period, erenumab reduced the monthly number of headache days by 2.8 days among 89 patients (baseline: 15.7 mean headache days per month) .
Our case provides a first observation that erenumab can also be effective in persistent post-traumatic headache following severe traumatic head injury even decades after the onset of symptoms. Since persistent post-traumatic headache is a common health issue, robust controlled studies on anti-CGRP-receptor treatment should be undertaken.
Therefore, erenumab should be considered as a therapy, which seems to be safe, convenient, and low in side effects in the treatment of persistent post traumatic headaches with migraine-like phenotype.