Do you remember your last visit to the ER?

(If you’ve never been to the ER skip this first paragraph and start from the second paragraph).

You were most likely frustrated by the amount of time you spent there, and you were probably surprised by how many tests you went through before you left. From blood tests to imaging studies, to checking if your pupils dilate with light, to listening to your heart and so forth. These tests may not have all been related to the condition you were suffering from – rather, many conditions that you might have been suffering from were eliminated as a result of this process. This is called differential diagnosis.

In the blog post I’ll try to briefly explain differential diagnosis and why it is so important, specifically for physical therapy and sports performance.

A diagnosis is a label for a specific condition that helps to communicate the characteristics of the condition clearly to other health care professionals.

On the other hand, differential diagnosis is a list of possible diagnoses (from the most likely to the less likely) deducted from the examination of the patient.

In physical therapy terms, unlike in other health care professions, the diagnosis is used to understand how the condition affects the individual as it relates to function. This is because therapists work to improve the function of the whole person, as well as the function of the individual system effected by the condition.

The differential diagnosis is built during the initial session. During the initial visit to a physical therapist the client should, in my opinion, be asked as many questions as possible about the symptoms s/he is experiencing (assuming the therapist already has the medical questionnaire and history in his/her hand). This is an extremely important step as the therapist begins creating a list of some possible conditions that may relate to the signs and symptoms the client has.

This differential diagnosis list should be taken into account as the second step of the process, the examination, begins. During the therapist’s examination some of the conditions on the list may be confirmed and some may be eliminated, depending on the results of the examination. This process of differential diagnosis is time consuming, as a lot of data is gathered and analyzed.

As an experienced physical therapist, I have to be aware of the correlation between different conditions and signs and symptoms. This is specifically important because all systems in our bodies may mimic the musculoskeletal conditions that I was taught to treat.

The endocrine, hematological, cardiovascular, pulmonary, immunologic, integumentary, gastrointestinal, renal, hipatic and biliary systems can all mimic orthopedic and musculoskeletal conditions.

Therefore, I know that I may sometimes see a client who doesn’t need any physical therapy at all.

Let’s look at the example of a client with low back pain, perhaps a professional basketball player. It is estimated that some clients who are seen in outpatient physical therapy clinics for low back pain are actually suffering from a non-physical therapy condition. Here is a quick breakdown from a study that was published in the early 2000’s: 4% will have a fracture/s related to osteoporosis, 2% forward displacement of vertebral body or fracture of one portion of the vertebrae, 2% visceral disease, 0.7% cancer and 0.5% infection.

Unfortunately, it’s not uncommon for me as a therapist to refer clients to other health care professionals, as well as to see errors that other physical therapists have made without taking into account the unneeded, unjustified treatment that is being given to their clients.

Differential diagnosis is ongoing and may change over time depending, among other factors, on further evaluation and examination, interventions, checking outcomes and taking into account the results of diagnostic imaging studies, and consulting with other medical professionals. This is not an easy task but it can save lives!