Should neurophysiological criteria for diagnosis of carpal tunnel syndrome be different for patients with diabetes mellitus?

Abstract

Background: Diabetes mellitus (DM) is a common association with CTS. The gold standard of diagnosis is nerve conduction studies. Boston Carpal Tunnel Questionnaire (BCTQ) is a self applied questionnaire which evaluates the severity of the symptoms and the functional status in CTS.Objectives: We aimed to find out whether accepted neurophysiological criteria for diagnosis of CTS are applicable to patients with DM.Patients and method: Following neurophysiological parameters were measured in clinic patients with DM; median motor distal latency (MMDL), median and ulnar-sensory distal latency difference (MUDLD), median and ulnar sensory nerve conduction velocity difference (MUNCVD). Distal latencies were compared with normal values available for the same laboratory. Patients with BCTQ score of zero was considered as asymptomatic and others; symptomatic. Percentages of subjects fulfilling different neurophysiological criteriato diagnose CTS were calculated i.e. MMDL ≥ 4.5 m/s, median sensory nerve conduction velocity (MSNCV) ≥40 m/s, MUNCVD ≥ 10 m/s, MUDLD ≥ 1 m/s.Results: Among the 70 normal controls the mean MMDL was3.36 ms ± 0.53. In of 51 (females 68.6%, mean age 59.86 years) consented patients 102 hands were tested. There were 61 asymptomatic hands with zero BCTQ. Mean ± SD of MMDL in themwas 4.30 ± 1.01. According to the above neurophysiological criteria 31.14%, 60.6%, 16.3% or 32.78% will be misdiagnosed as CTS. Among the symptomatic subjects mean MMDL was4.92 ± 1.74. The corresponding proportions according to neurophysiological criteria for symptomatic patients were 48.87%, 48.87, 32% or 60.97%.Conclusion: Accepted neurophysiological criteria will over-diagnose CTS in patients with DM. Different diagnostic criteria should be used in them to confirm CTS. Background: Diabetes mellitus (DM) is a common association with CTS. The gold standard of diagnosis is nerve conduction studies. Boston Carpal Tunnel Questionnaire (BCTQ) is a self applied questionnaire which evaluates the severity of the symptoms and the functional status in CTS. Objectives: We aimed to find out whether accepted neurophysiological criteria for diagnosis of CTS are applicable to patients with DM. Patients and method: Following neurophysiological parameters were measured in clinic patients with DM; median motor distal latency (MMDL), median and ulnar-sensory distal latency difference (MUDLD), median and ulnar sensory nerve conduction velocity difference (MUNCVD). Distal latencies were compared with normal values available for the same laboratory. Patients with BCTQ score of zero was considered as asymptomatic and others; symptomatic. Percentages of subjects fulfilling different neurophysiological criteriato diagnose CTS were calculated i.e. MMDL ≥ 4.5 m/s, median sensory nerve conduction velocity (MSNCV) ≥40 m/s, MUNCVD ≥ 10 m/s, MUDLD ≥ 1 m/s. Results: Among the 70 normal controls the mean MMDL was3.36 ms ± 0.53. In of 51 (females 68.6%, mean age 59.86 years) consented patients 102 hands were tested. There were 61 asymptomatic hands with zero BCTQ. Mean ± SD of MMDL in themwas 4.30 ± 1.01. According to the above neurophysiological criteria 31.14%, 60.6%, 16.3% or 32.78% will be misdiagnosed as CTS. Among the symptomatic subjects mean MMDL was4.92 ± 1.74. The corresponding proportions according to neurophysiological criteria for symptomatic patients were 48.87%, 48.87, 32% or 60.97%. Conclusion: Accepted neurophysiological criteria will over-diagnose CTS in patients with DM. Different diagnostic criteria should be used in them to confirm CTS.