When Carpal Tunnel Surgery Doesn't Work: Predicting Results of a Second Surgery
Imagine you have carpal tunnel syndrome that has not responded well to conservative (nonoperative) treatment. After having surgery to release the carpal tunnel but you didn't get the results you had hope for. Instead, the pain remains in your wrist and hand. The numbness and tingling in your thumb and first two fingers is enough to drive you crazy some days. You ask yourself: is it worth it to have a second surgery? If it didn't work the first time, how can you be sure the procedure will be successful if repeated?
These are the questions surgeons and patients face in about five per cent of carpal tunnel release cases. Some studies have been done to show that steroid injection into the carpal tunnel before the primary (first) surgery is a good predictor of symptom improvement after surgery. Could this same approach be used after a failed first surgery before considering a second (revision) release?
The surgeons who conducted this study injected the wrists of 23 patients (for a total of 28 wrists because a couple of people had carpal tunnel in both wrists). The patients involved ranged in ages from 29 to 85 years. Some of the patients had symptoms 40 years after the first surgery.
Everyone was carefully evaluated before injection. The surgeons wanted to make sure the persistent symptoms were really coming from pressure on the median nerve as it passed through the wrist bones forming the carpal tunnel.
A single injection of cortisone into the carpal tunnel space was given to each patient. Results were recorded based on whether or not the symptoms were relieved or eliminated. Then the second carpal tunnel release was performed. Patients were followed for six months after the second surgery. They were re-evaluated at regular intervals during that time.
Measures of success included symptom improvement and patient satisfaction. A positive report of patient satisfaction was defined as being willing to have the second surgery again if they had to do it all over again. Patients who had enough symptom relief were more likely to say the gains received by a second surgery were enough to be satisfied that a second surgery was worth it.
In this group of 23 patients (28 wrists), 23 wrists had complete pain and symptom relief. Five patients were unchanged after the revision surgery. Three of the patients who did NOT have any change in symptoms DID have symptom relief (or improvement) with the steroid injection.
After analyzing all the data, the researchers concluded that the steroid injection by itself wasn't statistically significant enough to predict surgical success. The surgeon's evaluation of the patient (history and clinical observations/tests) alone was not able to predict the results either. But when combined together (results of injection with the results of the surgeon's evaluation), they concluded that this approach could serve as a good screening tool.
They also pointed out that electrodiagnostic tests of nerve conduction velocity and muscle function (electromyography) are not useful with patients who have recurrent carpal tunnel syndrome. Studies show electrical changes can continue even after a successful primary carpal tunnel release.
The information gained in this study is important because carpal tunnel surgery isn't always successful. And that leaves the patient and surgeon trying to figure out what to do next. No one wants to have another surgery without some hope or assurance that it will work.
Studies show that failure rates after revision carpal tunnel release can be as high as 40 per cent. Up to 80 per cent of patients report improvement after a second surgery but say there are still some symptoms present.
Having a preoperative test of this kind that can be used to help screen for success is a start. The authors suggest further studies using more than one injection before revision surgery to see if that approach may be even more successful -- possibly even eliminating the need for a second surgery.
John D. Beck, MD, et al. Predicting the Outcome of Revision Carpal Tunnel Release. In The Journal of Hand Surgery. February 2012. Vol. 37A. No. 2. Pp. 282-287.