تعيين فراواني نسبي عصب پرونتال فرعي APN در همراهان سالم بيماران مراجعه كننده به بيمارستان پورسينا رشت

Determination ofrelative frequency ofaccessory peroneal nerve in normalpatientsʹ attendants refered to Rasht Poursina Hospital

Introduction: The most common anomalous innervation in the lower exterimity in nerve conduction studies(NCS) is the accessory peroneal nerve (APN), that originates from distal superficial peroneal nerve. It travels down the lateral calf, posterior to lateral malleolus ;innervates extensor digitorum brevis (EDB). This anomaly should be suspected when proximal stimulation of common peroneal nerve at the knee elicites higher amplitude compound muscle action potential (CMAP) than distal stimulation. Posterolateral ankle stimulation over the APN is confirmatory. Our purpose of this study is determining the relative frequency of APN generally, in any gender and foot laterality separately; comparison of innervatory pattern of deep peroneal nerve (DPN) and APN to EDB. Methods & materials: In this study, we tested 224 (112 men and 112 women) asymptomatic subjects without risk factors for neuropathy. Recording electrodes were placed on the belly of EDB with a supramaximal stimulation to the anterior and lateral ankle and below fibular neck; CMAP of each site was recorded. Chi square test was used for data analysis. Results: The existence of APN was found in 39 subjects (17.41%) and 72 legs (16.07%). The anomaly was bilateral in 33 subjects (84.61 %). One patient had complete innervation of EDB by APN in both legs (a rare condition). In 64 legs (88.9%) CMAP Amp of DPN was larger than or equal to CMAP Amp of APN. In only 8 legs (11.1%) CMAP Amp of APN obviously exceeded the CMAP Amp of DPN. In subjects with APN 56.41% were men and 43.59% were women. This difference wasnʹt statistically significant. (P value=0.423). The laterality of APN was 51.38% in left and 48.62% in right side. This difference wasnʹt significant too (P value=0.814). Conclusion: The results of this study show that APN is not uncommon and we must pay attention to its presents in electrodiagnostic studies.