Terminology & Explanations

Terminology in the medical-legal field can be confusing. Let’s make sure we’re all on the same page.

Diagnosis is Key

To properly fix a problem one must first diagnose what is causing it. Often times when medical problems are misdiagnosed they progressively worsen ultimately resulting in permanent damage or death. The sooner an accurate diagnosis is made the better the prognosis as prompt appropriate treatment has a better chance of resolving the condition. This is true whether we are dealing with a back strain or a serious cancer. A physician’s ability to diagnose the problem is instrumental in successful treatment.

In medical school the best instruction I ever received was that 80% of the diagnosis lies in the history. If you ask the right questions and listen well to the patient’s answers many times the diagnosis can be made before any fancy, expensive tests are employed. A skillful exam will also help to pinpoint the diagnosis. And yes at times we will rely on diagnostic imaging or lab tests to confirm or exclude a diagnosis.

Diagnosis is also important for determining causation. When we look at an outcome we need to know what the diagnosis was that led to that outcome. Working backwards we can then determine if it is plausible for an event to cause the diagnosis that leads to the resultant outcome. If there is no more likely explanation to cause the diagnosis than causation can be determined.

For a patient that suffers from low back pain the physician must first determine when it started, what makes it better or worse, where is it located and is it associated with pain down the leg or leg weakness. These complaints are part of the history that helps formulate a differential diagnosis. The exam and subsequent tests will eventually lead to a specific diagnosis that can result in appropriate treatment. However when the outcome is less than desirable the question of cause may be raised. For the patient with a herniated disk and pinched nerve resulting in back and leg pain after a car accident it seems logical that the force of the accident caused the disc to herniate and the back and leg to become symptomatic. However, if the patient had previous back pain and degenerative disc disease, causation may not be so obvious. Regardless an accurate diagnosis is needed to determine cause.


Often the primary question raised by the referral source for the IME physician is to determine disability. Disability is the alteration of a person’s capacity to meet personal, social,or occupational demands or statutory requirements because of impairment. Disability is a relational outcome, contingent on the environmental conditions in which activities are performed. Whereas impairment is a loss, loss of use, or derangement of any body part or organ system, it’s affect on the inability to perform functionally is disability.

Diagnosis is once again instrumental in determining disability. Is the diagnosis treatable or is the condition quiescent or at maximal medical improvement. Does the condition limit the patient functionally due to weakness, loss of motion, imbalance, fatigue, pain or a host of other problems associated with their diagnosis. The more specific the diagnosis and objective the exam, the greater the arguments for or against disability.

Disability can also be determined for a specific job or partial or as a total inability to work in any capacity. Also the question of duration or permanency of the disability may be raised. When considering a patient’s ability to function one must weigh the significance of his condition, whether they have rehabilitation potential or if accommodations will allow the patient to function in the workplace.

When evaluating individuals with neurologic or musculoskeletal conditions we need to perform a thorough exam. Oftentimes additional information can be gained by having the patient undergo a Functional Capacity Evaluation (FCE) performed by a qualified and experienced therapist. It is also important to consider any behavioral or motivational factors that may be present. Ultimately the recommendation regarding a patient’s ability to work should be consistent with their diagnosis and associated physical findings and symptoms.


Determining causation is an important element to doing medical legal work. Whether it is a work-related or personal injury case, we are often asked to determine what caused the injury or resultant condition. This may seem like a straight-forward task but when the individual has a pre-existing condition or when the condition is the result of a secondary effect of an injury, making that determination can become complicated very quickly. For example, take an individual with a ten-year history of low back pain who falls from a ladder at work and suffers an acute lumbar strain. Determining what caused the lumbar strain, in this instance, seems fairly straight forward – it was the fall from the ladder. However, let’s say the individual goes through physical therapy and is prescribed medications and is also deemed to not be surgical, but they have persistent low back pain a year following the injury. Now, when we are asked to determine what caused the individuals chronic low back pain, the situation is not so straight forward. In these instances, we look to the guidance provided by the American Medical Association and in particular, the publication “AMA Guides to the Evaluation of Disease and Injury Causation”. We have adapted their methodologies and use three main criteria in order to make causation determinations. The first criterion is to determine whether the incident or trauma could have caused the outcome or diagnosis. The second criterion is to determine whether there is a strong correlation between symptom onset and the incident. The third criterion in establishing causation is to determine whether the diagnoses could be explained by a more plausible cause. In using this approach, we aim to have a systematic and non-biased approach to sorting through the often complex elements of an individual’s medical history to arrive at a causation determination.


Often times as physicians we are asked to calculate permanent partial impairment ratings. Impairment is defined as a significant deviation, loss or loss of use of any body structure or function in individual with a health condition, disorder or disease. Impairments are determined as a percentage of the body part involved and then converted to a percentage of the whole person. An injury may result in an impairment from 0 to 100% of the whole person depending on the severity of the condition. Impairment ratings are defined by anatomic, structural, functional and diagnostic criteria. An accurate exam is also important in determining impairment as is the specific diagnosis. Ultimately the system for determining impairment should be reliable so that different raters arrived at consistent impairment ratings when assessing the same individual.

To achieve consistency the American Medical Association has been publishing The Guides to Evaluation of Permanent Impairment since the 1950s. Every seven years a new edition is printed. The most recent edition is the Sixth Edition published in 2008. This addition continues to emphasize diagnosis as a key contributor to determining the impairment rating. There are also adjustments for the significance of the patient symptoms and functional abilities. The physical findings and diagnostic studies can also influence the impairment. In my opinion The 6th Edition provides a better template for determining impairment. However it is a more complicated process and physicians have been slow to accept and utilize this edition. Many physicians still rely on the Fifth Edition. Some jurisdictions require the use of specific references for determining impairment.

Generally impairment should not be determined until the patient has reached a point of maximum medical improvement (MMI). Until the patient reaches a point of maximum improvement their impairment may change. For instance if a patient needs surgery for an unstable joint their impairment prior to the surgery would be much higher as they would likely lack motion and stability of the joint. After the surgery they would potentially improve functionally and symptomatically. Furthermore their joint would become more stable and have greater range of motion. Their impairment would be much less after the surgery if the outcome was as described above. Similarly when determining impairment for brain or nerve injuries we need to wait until the patient has made maximum medical improvement. After they have fully benefited from therapy and time we can then accurately measure their neurologic findings which will help to determine the significance of their loss and resultant impairment.

When determining impairment the physician should cite the reference and include the page or tables that were used in calculating the percentage. Furthermore if a body part is converted to a larger part or whole person the methodology needs to be described. A properly calculated impairment rating should be easily understood by those reading the report. It should also be easily supported by the reference utilized to determine the PPI.

Independent Medical Examination (IME)

Independent Medical Exams are often requested to help in matters of dispute. The referral source needs to be identified by the examiner and the reason for the exam should be discussed with the patient as well. IME’s differ from your routine patient encounter in that the physician is not entering into a treatment relationship with the patient. To maintain an unbiased attitude no patient-physician relationship is established. The physician is usually provided records to review, obtains a history from the patient and performs a pertinent physical exam. She/he then answers the medical questions raised by the referral source by generating a report which details their findings.

Most often the IME physician is requested to address issues of causation. To do so an accurate diagnosis needs to be made. Questions regarding previous and future treatment needs are also often answered. Whether or not the patient has reached a point of Maximum Medical Improvement (MMI) can be another issue. If no further medical treatment will improve the patient’s condition, than they likely are at MMI. If so a Permanent Partial Impairment (PPI) may be requested. PPI’s involve a calculation that is driven by the diagnosis and severity of the condition. Most physicians use “The AMA Guide to Determine Permanent Partial Impairment” as a resource to maintain consistency and fairness when determining impairment. The patient’s capacity to function can also be addressed as disability issues may impact their future earning potential.

I have done IME’s for over 20 years. I an ideal situation the physician would be blinded to the source of the referral. However that is not possible so it is the responsibility of the IME physician to maintain impartiality and address all the issues honestly. As a physician we still have a responsibility to treat the patient with dignity and fairly. If we find a diagnosis that has been undertreated or missed it is our responsibility to identify it. Likewise if the patient has received adequate treatment and no further efforts are likely to improve their condition than this needs to be stated.

Our opinions will be based on our experience and training and can as well be supplemented by scientific evidence such as recent articles or medical textbooks when necessary. The physician may use terms such as medically “probable” or “more likely than not” when opining on diagnosis or causation. The medical-legal standard is always some variant of what is probable or likely, something that if converted to percentages would indicate something greater than 50%.

Exacerbation vs. Aggravation

When discussing an injury or resultant condition, two concepts that often arise are exacerbation and aggravation. These terms are not interchangeable and depending on the nature of the injury, they can have important implications to what is deemed compensable. For example, take an individual who has a history of osteoarthritis in their knee joint and then that individual has a fall at work where they injure that same knee, resulting in increased knee pain. Does that knee injury represent an exacerbation or an aggravation their pre-existing condition? Well, that depends. According to the AMA Guides to Permanent Partial Impairment, an exacerbation is defined at a temporary worsening of a condition that eventually gets back to a baseline. On the other hand, an aggravation is defined as a permanent worsening that does not get back to a baseline. In the example above, if the person’s knee pain settled back down to its baseline after some medications and physical therapy, then it would be considered an exacerbation of their pre-existing condition. However, let’s say the individual received some medications and physical therapy for the injury but had persistent pain and then was later found to have a new meniscal tear. In this instance, the individual would have suffered an aggravation of their pre-existing knee condition, since it never returned to a baseline and there was evidence of a new meniscal tear. The concepts of exacerbation and aggravation often arise when making causation determination due to the fact that there is often a pre-existing condition in the body part that is injured.