Ask Dr. Keith Roach M.D
Piriformis syndrome is diagnosed by skilled examiner
DEAR DR. ROACH: I had just about given up on controlling my sciatic nerve pain in my right leg. I also had no faith that physical therapy could help, but I was referred by my family doctor, so I went. Recently, a physical therapist assessed me and told me that there is a way to distinguish, by physical exam, between sciatic nerve pain caused by spinal problems and that caused by the piriformis muscle. I was told that my pain is not coming from my spine, and I'm finally getting some relief for a very painful problem I have had for several years.
Can you explain this to me, especially why I was not diagnosed for so long? I have had lumbar spinal surgery, lumbar spinal steroid shots and treatment by a pain specialist. I did have spinal stenosis and bone spurs. — B.W.
ANSWER: Piriformis syndrome is caused by the sciatic nerve being compressed by the piriformis muscle against one of the bones of the pelvis. It happens particularly in some athletes, but can occur in anyone. It is not a common cause of sciatic nerve pain, occurring in only a few percent of people, but it is worth considering. The diagnosis can be made by a skilled physical examiner, such as the physical therapist who made the diagnosis in you. Treatment is also by physical therapy, which is effective in most cases.
I often hear that this condition goes unrecognized. What upsets me in your case is that it took years for you to get properly diagnosed and treated. I can't fault a primary-care physician for not knowing everything: Nobody knows everything, certainly not me. However, when a condition goes on for a long time, it is appropriate to reconsider the diagnosis. In your case, it sounds like your doctor was misled by the spinal stenosis and bone spurs, and without excusing it, there is a term for that: It's called an 'anchoring heuristic error,' meaning that the physician became 'anchored' to the idea that the spinal stenosis was causing the pain. I often prescribe physical therapy, and I often rely on the therapist's experience and judgment.
DEAR DR. ROACH: A couple of days ago, you said metformin lowers the insulin in your blood. Doesn't it lower the blood sugar, not the insulin? — G.Z.
ANSWER: There are many different treatments for Type 2 diabetes (people with Type 1 diabetes are absolutely dependent on insulin). Some treatments for Type 2 diabetes work by increasing insulin (obviously, insulin injections do), but there are oral medicines, such as glipizide, which work by making the pancreas secrete more insulin. Insulin lowers blood sugar by bringing sugar into cells. However, other types of medicines work through different pathways. Metformin works primarily by keeping the liver from making additional sugar. This allows the insulin the body makes to work on dietary sugar alone, and thus decreases the need for insulin, and both blood sugar and blood insulin levels go down. Type 2 diabetes is a disease of insulin resistance, and there are other classes of medicine that work on the resistance to insulin, such as pioglitazone (Actos). Insulin has growth-factor properties, so medicines that reduce insulin levels sometimes help with weight loss. However, the choice of a particular medication for someone with Type 2 diabetes is complex, and there are many reasons other than insulin levels why a doctor chooses a particular drug for an individual. That being said, usually metformin is the drug of first choice in people with Type 2 diabetes who are overweight, since there is good evidence that it is better than most other drugs in that common situation.