An ultrasound study of anatomic variants of the sural nerve

ArticleinMuscle & Nerve 43(4):560-2 · April 2011with10 Reads
DOI: 10.1002/mus.21918 · Source: PubMed
There are anatomic variations of the sural nerve (SN). Knowledge of these morphological types and the length of the SN are important for planning surgical reconstruction of peripheral nerves. Our purpose was to classify the morphological types of the SN by using ultrasound. Two-hundred SNs in 100 normal subjects were examined by ultrasound with 13-MHz linear-array transducers. Classification of the SN was evaluated by its formation. The distance between the union and the distal point of the lateral malleolus was measured. SN variants could be classified into three types: type I (81%); type II (18%); and type III (1%). In type I, the average length of the SN was 15.8 ± 5.7 cm. The morphological types of the SN can be determined using ultrasound. Ultrasound classification of the SN is useful with regard to donor nerve surgical reconstruction of peripheral nerves.
    • "In one of these, sural nerve conduction studies from healthy adults were done in addition to the cadaver studies showing highly variable sural nerve formation (Pyun and Kwon, 2008 ). Recently, an ultrasound study of anatomic variants of the sural nerve has shown similar variations as the cadaver studies (Zhu et al., 2011). These studies have mainly focused on surgical implications such as reconstruction of peripheral nerves, since the sural nerve is commonly used for nerve biopsies as well as a convenient source for nerve grafting. "
    [Show abstract] [Hide abstract] ABSTRACT: Objective Anatomical variation of the sural nerve has been documented in numerous cadaver studies. The sural nerve conduction parameters can potentially be influenced by the sural nerve type A formation formed by the union of the medial sural cutaneous nerve (MSCN) and the peroneal communicating branch (PCB) and the type C formation with the sural nerve formed solely by the PCB. Methods In 17 out of 240 prospectively examined subjects referred for polyneuropathy a suspicion of an anatomical variation of the sural nerve was raised due to decreased amplitude or substantial side-to-side variation (> 50%) of the sensory nerve action potential (SNAP) in disproportion to the clinical findings. To verify the variation the sural nerve was examined further with surface electrodes and near-nerve technique, including extra lateral and distal needle placements. Results In all 17 subjects an anatomical variation affecting the sural SNAP was confirmed as a normal sural SNAP could be obtained by changing the electrode placement. The most frequent variation, seen in 15 subjects, was a type A formation with union of the MSCN and the PCB distally at low calf, while a type C formation was seen in 2 subjects. Conclusions In case of a decreased sural SNAP amplitude or substantial side-to-side variation in disproportion to the neurologic evaluation, an anatomical variation instead of pathology could be suspected and a different electrode placement be considered. Significance Neurophysiologists should be aware of different types of formations of the sural nerve which may cause misinterpretations of nerve conduction studies, especially when needle electrodes are used.
    Full-text · Article · Oct 2014
    • "The site of union of the MSCN and LSCN is known to be highly variable. An ultrasonographic study reported that the SN had a length of 10-20 cm in 74.5% of the type 1 SNs [6]. Another study using cadavers reported that the union occurred in the distal third of the leg (67.4%) [4]. "
    [Show abstract] [Hide abstract] ABSTRACT: To understand various morphologic types and locations of the sural nerve (SN) that are important for nerve conduction studies or nerve grafting procedures. The aim of this study was to describe the course and variations of the SN based on ultrasonographic findings for an adequate nerve conduction study. A total of 112 SNs in 56 volunteers with no history of trauma or surgery were examined by ultrasonography. The location and formation of the SNs in relation to the medial and lateral sural cutaneous nerve were investigated. We measured the horizontal distance between the SNs and the midline of the calf at the level of 14 cm from the lateral malleolus, and the distance between the SNs and the most prominent part of the lateral malleolus. SN variants was classified into four types according to the medial and lateral sural cutaneous nerve; type 1 (73.2%), type 2 (17.9%), type 3 (8.0%), and type 4 (0.9%). The mean distance between the SN and the midline of the calf was 1.02±0.63 cm, the SN and the most prominent part of the lateral malleolus was 2.14±0.15 cm. Variations in the location and formation of the SN was examined by ultrasonography, and the results of this study would increase the accuracy of the SN conduction study.
    Full-text · Article · Feb 2014
    • "The sural nerve is formed by the union of medial sural cutaneous nerve (a branch of tibial nerve) and the lateral sural cutaneous nerve (a branch of the peroneal nerve). A US study conducted by Zhu and colleagues (Zhu et al., 2011) showed that in 100 healthy subjects (for a total of 200 sural nerves) this union occurs in 81% of subjects with an average length of 15.8 ± 5.7 cm from the lateral malleolus and that in the remaining subjects there is only one branch, but they did not measure the CSA. This is very important in order to be sure to measure the entire nerve; in our study we measured the CSA in the third medium of the calf (approximately 12 cm above the lateral malleolus) where the nerve should be composed by both branches. "
    [Show abstract] [Hide abstract] ABSTRACT: OBJECTIVE: Nerve ultrasound (US) has been used to study peripheral nerve disease, and increase of the cross-sectional area (CSA) has been described in demyelinating polyneuropathy. The objective of the current study is to characterise the US features of the sural nerve in a sample of Charcot-Marie-Tooth (CMT) 1A patients. METHODS: A total of 20 CMT1A patients were enrolled. As control group we studied 37 age- and sex-matched subjects. All patients underwent clinical examination, neurophysiology and US evaluation of the bilateral sural nerve and right ulnar nerve. US results were correlated with neurophysiology and clinical data. RESULTS: Sural nerve CSA was not increased in the majority of patients (70%), whereas an increased ulnar nerve CSA was present in the whole sample. Inverse relations were found between CSA of the ulnar nerve and body mass index (BMI) (p<0.0002, R=-0.8) and CSA of the sural nerve and age (right 0.006, R=-0.6, left 0.002, R=-0.6 and left and right p=0.00003, R=-0.4). CONCLUSIONS: US showed ulnar CSA enlargement and normal sural nerve CSA. SIGNIFICANCE: The significance of normal sural nerve CSA in CMT1A patients need to be further investigated, possibly through longitudinal studies.
    Article · May 2013
    C PazzagliaC PazzagliaI MinciottiI MinciottiD CoraciD Coraci+1more author...[...]
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