Study of variations in medial sural cutaneous nerve, lateral sural cutaneous nerve and peroneal communicating nerve.

The sural nerve complex includes the Medial sural cutaneous nerve (MSCN), Lateral sural cutaneous nerve (LSCN), Peroneal communicating nerve (PCN) and Sural nerve. The sural nerve is the most frequently used donor nerve for peripheral nerve grafting. LSCN can be an alternative to sural nerve in situations requiring a limited length of nerve graft material, the peroneal communicating nerve may also be harvested. Fifty lower limb specimens were dissected and data was collected. The study included 16 male and 9 female cadavers. MSCN was observed in all 50 specimens, out of which 74% specimens had normal course and 22% had a transmuscular course. LSCN was present in 82% of specimens. PCN was arising from Common Peroneal Nerve (CPN) directly in 16% and as a common trunk with LSCN in 14% of specimens. PCN was absent in 28% of cases. So knowledge of variation in these nerves will help the surgeons while considering these nerves for nerve grafting.

Transmuscular course of the medial sural cutaneous nerve and its clinical implications.

Variations of nerve are not only of anatomic and embryological interest but also of clinical importance. Their adequate knowledge will help in increasing surgical precision and decreasing morbidity. Anatomical variations in the formation of the sural nerve are common, although the topographical localization of this nerve is constant. In this report, we describe a case of an anomalous course of the medial sural cutaneous nerve which descended through the gastrocnemius via a tunnel formed within the muscle. Such anatomical variation of the sural nerve is clinically important when evaluating sensory axonal loss in distal axonal neuropathies since sural nerve mononeuropathy is less likely to occur.

The Relative Contributions of the Medial Sural and Peroneal Communicating Nerves to the Sural Nerve

The medial sural cutaneous nerve (MSCN) and peroneal communicating nerve (PCN) conjoin in the calf area to form the sural nerve (SN). In previous anatomic studies, there was unresolved debate as to the main contributor to the sural nerve, and the relative contributions of MSCN and PCN had not been studied. The purpose of this study is to determine their relative neurophysiologic contributions to the SN by nerve conduction study (NCS). A total of 47 healthy subjects (25 males and 22 females, mean age 29.6+/-10.4 yrs, range 20-59 yrs) participated in the study. This study employed the orthodromic nerve conduction technique: stimulation at the ankle and recording at the mid calf (SN); specifically, we preformed stimulation at the mid calf (MSCN, PCN) and recording at 14cm proximal to the middle of the popliteal fossa (MSCN) and fibular head (PCN). The onset and peak latencies (ms) were SN 2.3+/-0.2 and 3.0+/-0.2; MSCN 2.1+/-0.2 and 2.8+/-0.2; and PCN 2.1+/-0.2 and 2.8+/-0.2. The peak-to-peak amplitudes (micro) and areas (nVsec) of the SN, MSCN, and PCN were 9.7+/-3.9, 7.0+/-4.7, and 5.0+/-3.2; and 7.2+/-2.9, 5.7+/-3.4, and 4.0+/-2.4, respectively. The side-to-side difference was not statistically significant. The main contributor to the SN was found to be the MSCN. The relative contribution ratio of the MSCN to the PCN was 1.37:1 by amplitude and 1.42:1 by area. However, in 32.9% of the subjects, the contribution of the PCN was greater than that of the MSCN.

Anatomical Investigation of Sural Nerve and Its Contributing Nerves

OBJECTIVE: To identify the location and formation of the sural nerve and its contributing nerves. METHOD: Fourteen lower limbs of 7 adult cadavers were anatomically dissected. The location and formation of the sural nerve (SN) in relation to the medial sural cutaneous nerve (MSCN) and the lateral sural cutaneous nerve (LSCN) were investigated. The length and diameter of the SN and contributing nerves were measured and the differences of the results were analyzed. RESULTS: Twelve SNs were formed by the union of the MSCNs and LSCNs, and 2 SNs were direct extensions of the MSCNs. The point of formation of the SN by union of the MSCN and LSCN was found in the middle third of the legs in 66.7% of SNs examined. The union sites of the SNs were located at 40.58+/-13.97% of the length of lower leg from the tip of lateral malleolus and 55.84+/-6.48% of the calf width from the medial border of the calf. There were significant statistical differences of diameter among nerves (p<0.05) and no significant difference of length between MSCN and LSCN. CONCLUSION: The results of this cadaveric study would increase the accuracy of the sural nerve conduction study and provide the locational information for precise surgical approach.