What secondary means
A condition does not have to have started in service to be service-connected. When a service-connected condition causes a separate condition, the second condition can be service-connected on a secondary basis. Aggravation — a service-connected condition making another condition worse — is part of the same framework.
Secondary connection answers the connection question only. Once a migraine condition is connected, its percentage is evaluated under the same DC 8100 criteria as any other migraine claim: frequency and prostrating character over the last several months.
The three things the evidence has to show
A secondary claim is built from three elements, and the file should address each one directly:
- A current migraine diagnosis, documented by a provider
- A primary condition — here, PTSD — that is already service-connected
- A nexus: medical evidence linking the migraine condition to the service-connected primary, by causation or by aggravation
Building the link evidence
The nexus is usually the contested element. A useful medical opinion does more than state a conclusion: it identifies the records reviewed and explains the reasoning that connects the two conditions in your case. Treatment records that document both conditions over time give that opinion something to rest on.
Your own statement covers what only you can report: when migraines began or changed, and how they present. Keep it factual and dated, and keep the headache log running — connection and rating are separate questions, and the log answers the rating one.
Nexus evidence checklist: migraine secondary to PTSD
A secondary claim stands on the link. Use this checklist to organize the evidence that shows each element before you file.