progression of carpal tunnel syndrome according to electrodiagnostic testing in nonoperatively treated patients

background:  this study tested the null hypothesis that nonoperatively treated patients would not show disease progression of carpal tunnel syndrome (cts) over time according to median nerve distal motor latency (dml) on two electrodiagnostic tests.   methods:  this retrospective study analyzed sixty-two adult nonoperatively treated patients who were diagnosed with cts confirmed by a minimum of two electrodiagnostic tests at our institution between december 2006 and  tober 2012. a wilcoxon signed-rank test was conducted to test the difference between electrodiagnostic measurements between the first and last test. results: the mean time between the first and last electrodiagnostic test was 26±12 months (range, 12 to 55 months). the only electrodiagnostic measurement that increased significantly was the difference between median and ulnar dml on the same side (r=0.19, p =0.038). the time between the electrodiagnostic tests was significantly longer for patients with at least 10% worsening of the dml at the second test compared to cases of which the dml did not worsen or improve a minimum of 10% (p =0.015).  conclusions: there is evidence that—on average—idiopathic median neuropathy at the carpal tunnel slowly progresses over time, and this can be measured with electrodiagnostics, but studies with a much longer interval between lectrodiagnostic tests may be needed to determine if it always progresses.