If there is a previously existing condition and is aggravated by work activity, it is compensable. Depending on the length of time the condition has existed and the last treatment for it, additional documentation may be needed from the authorized treating physician (ATP) to support this in order for the employer to continue with treatment. But, if you know something bad is going to happen (foreseeable) – it’s not an accident. (Example: Worker knows he is allergic to dishwashing detergent, but takes a job as a dishwasher – of course there will be an allergic reaction).
If a worker is provided with a pre-employment questionnaire it is crucial to include everything about past medical conditions even if they are symptoms which are not affecting you at the time. If an injury occurs and it is later found that you had a prior problem, but lied about it you could be barred with a fraud in the employment defense. If this defense is successful, you could be responsible for repaying all medical and financial expenses paid by the employer. You only need to share past medical conditions if a questionnaire is given or a physical required. The truth will then put the decision about you work abilities to the employer and their physician, protecting you in the long run from fraud allegations.