An electrophysiological study of Riche-Cannieu anastomosis / 中华物理医学与康复杂志

ABSTRACT

Objective To explore the optimal electrophysiologieal approach for detecting Riehe-Cannieu anastomosis(RCA),an anomalous anastomosis between the deep branch of ulnar nerve and the recurrent branch of the medial nerve in the palm of the hand,and to estimate its incidence. Methods One hundred subjects(56 male,44 female,mean age 37.8 years)without any hand motor or sensory dysfunction were selected randomly.The ulnar nerve was stimulated at both the elbow and wrist,and recordings were made from the abductor pollicis brevis,which is normally innervated by the medial nerve,to document any compound muscle action potentials(CMAP).CMAP recorded from both points during stimulation is an accepted indicator of RCA.Group A comprised 40 hands of 20 subjects,while group B included 160 hands of 80 subjects.Surface electrode stimulation was used in both groups.Surface and needle electrode recording was used in group A,while only needle electrode recording was used in group B.Results In group A,31 hands of 16 subjects were found to have RCA by means of surface electrode recording,but only 6 hands of 3 subjects were found to have RCA by means of concentric needle electrode recording.There was a difference of up t0 80.6% between results obtained by the 2 recording methods.In group B,35 hands of 20 subjects were found to have RCA.A total of 41 hands of 23 subjects among the 100 were found to have RCA when concentric needle electrode recording was used(20.5%incidence). Conclusion The type of recording electrode influences the accuracy of RCA examination.An accurate and reliable result can be obtained by using a concentric needle electrode.The abductor pollicis brevis can be anomalously innervated by the ulnar nerve because of RCA.When both the medial and ulnar nerve have been injured.RCA might result in anomalous clinical symptoms and electrophysiological findings.Thoroughly understanding this anomaly is of crucial importance in the clinical evaluation and diagnosis of medial or ulnar nerve injury,as well as to avoid mistakenly interpreting the electrophysiological data when Riche-Cannieu anastomosis is present.