You can and should still file a claim, even if you have a pre-existing condition. Your damages sought will take into consideration your pre-existing health issues. If the other party aggravated the injury or condition they can be held responsible. These kinds of cases are often a bit more complex and a skilled personal injury attorney will be able to navigate through the process easier than you can alone. If expert witnesses are necessary to prove your case, hiring a legal team that has the proper resources will benefit your outcome.