With each personal injury claim you have what is called statute of limitations. The statute of limitations is different for each state so it is important that you contact a professional so you know if your brother has legal recourse.
If the statute of limitations has run or is expired you typically are prevented from bringing forth your claim, that is why it is so critical to contact a lawyer and pursue your claim. There are many aspects to each claim and there is no claim that is exactly identical so regardless of others who may have received great results from a claim, others may not.
If your brother is within the statute of limitations it will be critical to speak with a personal injury attorney immediately to determine what his legal recourse may or may not be.
If your brother has settled his claim prior to his new medical complications, you will likely be barred from bringing forth a new claim. Once again, every matter is unique and you should always contact a legal professional if you have any questions regarding the time limits on any legal claim.