Correlation Between MRI,Clinical Findings And Electrophysiological Investigation For Diagnosis Of Idiopathic Carpal Tunnel Sydrome

ObjectiveTo explore MRI,clinical evaluation and electrophysiological investigation in dianosticvalue about the severity of idiopathic carpal tunnel sydrome.To investigate the benefit ofusing MRI for the diagnosis of idiopathic carpal tunnel syndrome.MethodsThirty-one patients with idiopathic carpal tunnel sydrom were assessed by MRI,clinical evaluation and electrophysiological investigation.Clinical evaluation includedsymptoms severity score and two-point discrimination.Electroneuromyography parametersincluded motor nerve conduction velocity,distal motor latency,compound muscle actionpotential amplitude of the median and ulnar nerves and sensory conduction velocity andsensory latency and sensory action potential amplitude of the median and ulnar ner-ves.parameters obtained from MRI evaluation included the cross-sectional areas of themedian nerve and tunnel,the flattening ratios of the median nerve and the palmar bowingof the flexor retinaculum.The cross-sectional areas of the median nerve and tunnel weremeasured at following levels:radioulnar joint,pisiform bone and hook of hamate bon-e.Parameters were analyzed using the Pearson correlation or Spearman rank correlation.Forcomparison of median nerve section area at different levels and between flattening ratiosrepeated the t-test or Wilcoxon signed ranks test were applied.A p-value lower than0.05was considered statistically significant.ResultsThe mean age of31subjects was (44.39±9.37) years.The mean duration of symptomswas (37.84±67.74) months.The mean body mass index was (25.38±2.56) kg/m~2.The meansymptoms severity score was (2.27±0.8).The mean values for static two-point dis-crimination were (4.0±2.02) mm.There was a positive correlation between the body massindex and the symptoms severity score (p=0.01),indicating that the higher body mass index the greater symptoms severity score,and we did not find statistically significant co-rrelations between other parameters.In the median nerve conduction studies, The meansensory conduction velocity and sensory latency were (33.77±8.34)m/s and (5.29±1.2)m/s,respectively.There was a negative correlation between sensory latency and sensoryconduction velocity (p<0.01).The mean of the flexor retinaculum was (0.17±0.04).Thecross-sectional area of the carpal canal at pisiform level (2.47±0.36)cm~2was significantlylarger (p<0.01) than the area measured at hamate level (2.15±0.31)cm~2.The mean of thecross-sectional area of median nerve at radio-ulnar joint,pisiform and hamate level were(0.16±0.06)cm~2，(0.22±0.07)cm~2and (0.19±0.04)cm~2,respectively.There were significantdifferences among the three parameters (p<0.05).The flattening ratios at radio-ulnarjoint,pisiform and hamate level were (1.76±0.48)，(2.06±0.47)and (2.2±0.65)， res-pectively.When comparing the flattening ratios at three levels,a significant difference wasidentified between radio-ulnar joint and hamate level,and a significant difference wasidentified between radio-ulnar joint and pisiform level too.With exception of median nervearea at pisiform level,there was not correlation between MRI parameters and findingsobtained by clinical assessments and electrophysiological measurements.Cross-sectionalarea of median nerve at pisiform level correlated positively with two-point discrimination(p<0.01) and sensory latency (p<0.05), and negatively with sensory nerve conductionvelocity (p<0.05).ConclusionMRI was a valuable method in dianostic value about the severity of idiopathic carpaltunnel sydrome.MRI was complementary to nerve conduction study,and there was addedbenefit of using MRI for the diagnosis of idiopathic carpal tunnel syndrome. The area ofmedian nerve measured by wrist magnetic resonance at pisiform level was a valualeindicator to grad the severity of disese.