Excerpt from the page Military Disabilities Made Easy
Assigning Military Disability Ratings based on the VASRD (Veteran Affairs Schedule for Rating Disabilities 38 CFR 4 Schedule for Rating Disabilities) is already complicated. To make matters worse, many conditions are either not in the VASRD or go by a different name.
Conditions that are not in the VASRD are rated “analogously” with a condition that is in the VASRD. “Analogous” in this case means the condition that is closest to the overall condition, that best describes the main symptoms, or that has the same treatments. For example, sinus headaches are not in the VASRD, only migraine headaches. If you have sinus headaches that are severe enough to be eligible for a rating, then they can be rated under the VASRD Code for migraine headaches, since that is the condition that is closest to your condition, and would be expected to cause a similar degree of disability.