Carpal tunnel syndrome (CTS) is the most frequent neuropathy observed in maintenance haemodialysis patients. In spite of the established diagnostic guidelines and many different methods of nerve conduction testing, sometimes difficult to distinguish very advanced CTS (absent median motor and sensory responses) from uremic neuropathy. In the last few years the 2LI-DML test has been accepted as a reliable method for the diagnosis for very advanced stage of CTS. The aim of this study was to evaluate the usefulness of nerve conduction testing based on the interlatency difference (2LI-DML) between the second lumbrical (2L) and second dorsal interosseous (21) muscles in the diagnosis of severe forms of carpal tunnel syndrome in long-term hemodialysis patients with superimposed polyneuropathy. From the group of 40 patients with CTS the 2LI-DML test was used in five cases of long-term hemodialysis with severe damage of the median nerves (absent median motor and sensory responses) and with forearm arteriovenous fistulas and concomitant uremic polyneuropathy. The presence of forearm arteriovenous fistulas makes needle electrode test impossible to apply. The performed 2LI-DML test allowed for a confirmation of clinical diagnosis of CTS in all the patients. A mean difference of motor latency between the second lumbrical and the second interosseous muscles was significantly prolonged and amounted to 10.91+2.36 ms.
Conclusions: The 2LI-DML test is the only test that may be used to diagnose CTS in patients with severe damage of the median nerves and with forearm arterio-venous fistulas and superimposed polyneuropathy. The test is fast, simple to perform and well-tolerated by such patients.