https://www.sciencedirect.com/topics/medicine-and-dentistry/periaqueductal-gray

It's a question that periodically gets brought up. Some patients have a striking tendency to develop recurrent injuries, pain patterns consistently or exclusively on one side of their body. They wonder if this is a coincidence, or if there may be a master mechanism driving that.

Short of being broadsided by a truck on one side of your body, you do need to look for reasons why patients continuously develop problems unilaterally. Here are some of the two most common mechanisms I have seen:

– from a mechanical standpoint, a chronic mechanical disruption or instability of the lower extremity can create stress on one side of the body. This is the case with undiagnosed or uncorrected short legs, which I have seen in a surprising number of adult patients who are told of it for the first time. The other mechanical issue that can affect one side of the body is significant upper cervical subluxation patterns, which affect utilization movement and coordination on one side of the body and leads to inefficiency injuries.

– Probably more commonly there is a neurological "glitch" in the central nervous system which affects sensory perception, motor response and coordination to one side of the body and leads to chronic recurrent pain and injuries unilaterally. A lot of people have the residuals of a very old mild traumatic brain injury causing these types of issues, although they are usually adamant they've never had such a thing. We can usually uncover that by doing a few subtle neurological testing for balance, vestibular function, and muscle tone symmetry between the right and the left side. There are several known neurological pathways descending from the brain that affect pain perception and modulation unilaterally in particular.

As always treatment depends upon correctly assessing what may be driving the issue, and trying to incorporate the right measures to correct it