Diagnostic Injections: A Pearl Oft Overlooked

     Today I had a patient Valerie whom has a difficult problem to diagnose. She has already had a major ankle surgery by skilled, well-meaning, surgeons in January 2009. She is not only not better, but slightly worse. She knew right after her surgery that the symptoms that had driven her to surgery in the first place were still there, and now she had another source of pain. The surgical pain is pretty much gone now, but what to do with her original problem. I suggested to her that we should do diagnostic injections with long-acting local anesthesia. I use 0.5% Bupivacaine (same as Marcaine or Sensorcaine) for these injections. They take 20 to 30 minutes to numb the area injected, and stay numb for around 5 hours. Valerie is a perfect candidate for this procedure since she has so many possible sources of pain. Since she has had pain since 2004, she has had bone scans, x rays, MRIs, and CT scans. All these tests have shown irregularities in different areas. The problem with all these tests is that with all their sophisication, in the end, they do not definitely tell you what is hurting. They suggest, but can not confirm definitely. Thus, here is the role of diagnostic injections.

     Valerie's tests have pointed me towards 3 joints, one tendon, and several ligaments as the possible source of pain. When she comes into the office I will inject 1 ml of local into the most probable location first. I told her she must break the Golden Rule of Foot: Once pain begins with activity, you must stop that activity. For these diagnostic injections, she must come into the office sore. She must break the rule. She says it will probably take several days of breaking the rule before she gets her foot/ankle angry enough. After the first shot, she will walk around 30 minutes or more and see what the effect was of the shot. Did it eliminate 100% of the pain, none of the pain, or some amount in between. Yes, sometimes 2 or more structures may be responsible for the pain. Sometimes, it is one structure that is injured, and several other areas sore secondary to the swelling, scar formation, limping, etc. Yet, sometimes, more than 1 structure is injured or damaged, making these shots more confusing.

     1 ml of local is enough diagnostically in the small joints or tendons of the foot and ankle. Probably more is needed for injections into major joints, like the knee.1/4 ml is needed for small ligaments in the foot/ankle. Our office is also nicely equiped with stationary bikes, ellyptical machines, treadmills, etc, when patients have needed various ways to attempt to produce pain. This technique works best when they come in sore, get the injection, wait 30 minutes, then try to produce the pain again. The patient must know how to reproduce the pain for this to work well.

     If the first shot does not completely eliminate the pain, about 1 hour after the first injection, a second injection is given and the procedure repeated. Again, a response is noted after the patient retries to produce pain. If the second shot fails to completely eliminate pain, about 1 hour after the second shot, a third shot is given. And so it goes. Normally, one or two shots is all that is needed, since the shots are given in order of the highest to lowest likelihood of eliminating pain. But, I have gone to 5 injections, making it a 5 hour ordeal for the patient, before trully finding the source of pain. Since the injections themselves take 1 minute for the doctor to give, the patient need only schedule a normal followup visit, but have no plans for the rest of the day. The patient is worked in between other patients for the shots if needed, after the first shot.

     In the 29 plus years I have been using these shots, inspired by my partner and world renowned orthopedist Dr James Garrick, only 1 patient after multiple shots found no relief whatsoever. Many patients have had only partial relief after multiple shots, and thousands have had complete relief after one, two, or three injections. The diagnosis has been refined, and treatment can be advanced to more specific treatments. Even in the most cloudy situations of diagnosis, I have found these shots to lend some light and better direction. In Valerie's case, when we find the source of pain, I will have to repeat the procedure one more time on another day, to verify I get the same results. This is because she has had pain for so long, and already failed one surgery, I must get it right!!

    But, diagnostic injections can also be used in fairly straight forward cases. Here they are used to confirm the diagnosis everyone assumes is correct. An easy diagnosis you say. A slam dunk.  I can think of two patients that come to mind with straight forward problems. Both had surgery by two top top surgeons, which are higher than top surgeons, and both were utter failures. Both presented to my office for second opinions. Both needed one diagnostic injection into the joint next to the operated joint and their pain was 100% eliminated. One needed a second surgery (first surgery on the subtalar joint, second surgery on the ankle joint), and the other did great with orthotic devices and physical therapy (first surgery on the ankle unsuccessful, with the injection pointing to the subtalar joint as the source of pain). Dr Garrick always said that your surgical results would be greatly increased if you would validate pre-operatively that local anesthesia could completely eliminate the pain. And you may find that surgery is not needed if you find a source of pain that may be rehabilitated. I sure hope this helps you.