The relationship of the double crush to carpal tunnel syndrome (an analysis of 1,000 cases of carpal tunnel syndrome).

In this series of 1,000 cases of carpal tunnel syndrome (888 patients) there is a statistically significant incidence of bilaterality in patients with cervical arthritis. There is also a statistically significant increase in the incidence of diabetes mellitus over the general population. These findings lend further support to Upton's Double Crush hypothesis. Further, the double crush syndrome predisposes to bilateral carpal tunnel syndrome and may be an important prognostic factor. It may also be an explanation for some of the failures following carpal tunnel surgery and lead surgeons to look for other associated systemic diseases or mechanical blocks, when attempting to alleviate recalcitrant symptoms.