I am a long-distant bicyclist with a few typical problems with neck pain and wrist/hand pain and numbness. I've been told I have a "double crush syndrome." Can you tell me a bit more about this and what to expect?
Neck pain, shoulder pain, thoracic outlet syndrome, carpal tunnel syndrome, and this diagnosis of neck pain and carpal tunnel syndrome (which together make up the double crush syndrome) are fairly common among bicyclists. In fact, in a recent study of just patients who were bicyclists, they found a high proportion of riders who had positive clinical tests for double crush syndrome. The exact mechanism by which this condition develops remains uncertain. It is believed that the symptoms at the neck and wrist/hand come from damage, injury, or compression of the same spinal nerve root. In fact, compression in one region has been shown to increase the likelihood of damage at another location along the nerve. A nerve in the wrist is actually more susceptible to problems when there is compression in the neck. Many experts have suggested various different ways in which this syndrome develops. It could have to do with the damaged nerve's ability to transport information further down. Perhaps there is a loss of blood supply. Or maybe the initial nerve damage leaves it stiff and no longer elastic enough to transmit messages along its length. Sometimes, another condition such as diabetes or thyroid disease is the missing link. But again, the exact mechanism by which carpal tunnel syndrome follows the initial neck pain remains a mystery. Physicians have found that electrodiagnostic testing is the most valid and reliable way to document nerve impairment linked with carpal tunnel syndrome. The same type of testing is not as reliable for documenting a double crush syndrome. Commonly used tests (e.g., Phalen's, Tinel's) that point to carpal tunnel syndrome and are confirmed with electrodiagnostic tests cannot be used reliably to diagnose a double crush syndrome. Without a clear mechanism of development of the double crush syndrome, treatment cannot be as specific as possible. Up until now, researchers have paid attention to types of treatment applied and then looked back to see which patients improved. By working backwards in this way, it may be possible to understand the mechanism underlying the loss of nerve function in more than one place along the nerve. But the problem is a bit more complex than it seems. Some studies show that patients with just carpal tunnel syndrome have better results after carpal tunnel release surgery compared with individuals who have the double crush syndrome. This would lead one to think it is necessary to have surgery at both sites of the nerve compression (neck and wrist). Yet other patients with double crush syndrome who have cervical decompressive surgery (without carpal tunnel release) have equally good results. Those results would suggest the need for cervical decompression before (or even alone without) carpal tunnel release. Not everyone agrees but some experts in this area suggest the following when faced with the dilemma of treating a double crush syndrome. First, the physician looks at symptoms, results of clinical exams, and performs electrodiagnostic testing. Second, all results are reviewed together with the big picture in mind. Third, when there is a double crush syndrome present, a surgeon will perform the least invasive surgical procedure first. Then the patient's symptoms are reassessed along with goals and expectations. The next step in the treatment plan is determined accordingly. The patient who continues to have pain and other nerve symptoms should be re-evaluated for a more proximal (closer to the neck) disorder of the nerve(s). If and when a clearer understanding of the mechanism underlying double crush syndrome is discovered, patient management can be re-visited. More appropriate and more consistently successful treatment can then be developed.