Sonography Evaluatino Of Cubital Tunnel Syndrome: Correlation With Electrophysiological Studies

ObjectiveTo evaluate the diagnostic value of sonography in the diagnosis of cubital tunnelsyndrome and to explore in patients with cubital tunnel syndrome if sonographicdifferences in ulnar nerve size correlate with severity stratification determined byelectrodiagnostic studies, by carrying out electrophysiological studies and sonography inpatients with cubital tunnel syndrome using electrodiagnostic diagnosis as the referencestandard.MethodWe examined prospectively thirty-five elbows of29patients, along with thirty-sixelbows of18controls whose age and gender were matched with the patients. Patients hadnerve conduction studies and needle electromyography, whereas controls had nerveconduction studies. All patients and controls had sonographic measurement of thecross-sectional area (CSA) of the ulnar nerve at three levels:2cm proximal to the medialepicondyle (CSA-prox),2cm distal to the medial epicondyle (CSA-dist) and at themaximum CSA (CSA-max) of the ulnar nerve found between these points, threemeasurements for each level were obtained, and an average value was calculated.Thirty-five pathological elbows were classified into mild, moderate and severe groupsaccording to electrodiagnostic studies. Compare the CSA of the ulnar nerve betweenpatients and controls at above three levels. Explore correlation between the CSA of ulnarnerve and severity stratification obtained by electrodiagnostic studies in patients withcubital tunnel syndrome. A receiver operating characteristic (ROC) curve was fitted to theCSA of ulnar nerve, using the electrodiagnostic studies as the reference standard, todetermine the optimum cutoff point and to evaluate the diagnostic value of sonographic inthe cubital tunnel syndrome. The data was treated with SPSS13.0, p<0.05is consideredstatistically significant. ResultsOvert muscle wasting was present in15elbows (43%), thirty-five pathological elbowsof29patients were classified into mild: ten elbows, moderate: eleven elbows and severe:fourteen elbows according to electrophysiological studies. There were no significantdifferences in age and gender between patients and controls (P>0.05). The CSAs at abovethree levels were significantly larger in patients than in controls (P<0.001). The CSA-maxin the patient group showed difference in severity stratification and was highly correlatedwith the severity obtained by electrodiagnostic studies: mild:(9.4±3.2)mm~2, moderate:(13.4±2.5)mm~2, severe:(17.0±3.2)mm~2(P<0.001,r=0.717).The CSA-prox and CSA-dist ofulnar nerve showed no difference in severity stratification(P=0.804,P=0.857) and had nocorrelation between electrophysiological severity. When the ROC curve was fitted forsonography using electrodiagnostic criteria as the reference standard, the best cutoff valueof CSA-max was7.8mm~2, which had a sensitivity of91%and a specificity of97%, thearea under the curve was0.960(95%CI,0.909~1.010) for the CSA-max.ConclusionsSonography played a positive role and showed a high accuracy in the diagnosis ofcubital tunnel syndrome. Sonography of ulnar nerve showed difference in the severitystratification of patients with cubital tunnel syndrome, it can evaluate the severity ofcubital tunnel syndrome.