Pearls &amp; Oy-sters: False positives in short-segment nerve conduction studies due to ulnar nerve dislocation

Kim, B. J.; Koh, Seong Beom; Park, K. W.; Kim, S. J.; Yoon, Joon Shik

doi:10.1212/01.wnl.0000297515.86197.2e

Cited by 28 publications

(36 citation statements)

References 10 publications

(13 reference statements)

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“…Localization of focal neuropathy is important for studying nerve conduction and is based on accurate measurement of the latency and amplitude of the compound muscle action potential (CMAP) and the distance between stimulation sites. Distance measurement error is one important factor that contributes to possible inaccuracies in determining nerve conduction while diagnosing UNE 3, 5, 6, 9–12. In this study, the distance measurement error was approximately 1.6 cm and caused 7.9 m/s of velocity overestimation.…”

Section: Discussionmentioning

confidence: 72%

Avoiding false‐negative nerve conduction study in ulnar neuropathy at the elbow

et al. 2011

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Section: Discussionmentioning

confidence: 72%

Avoiding false‐negative nerve conduction study in ulnar neuropathy at the elbow

et al. 2011

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“…It has been reported in healthy subjects as well as patients with UNE and might alter electrodiagnostic findings, resulting in false positive findings of conduction block at the elbow. 4 Assessment of ulnar nerve displacement at the elbow is of renewed interest due to the use of high-resolution ultrasonography with dynamic studies during elbow flexion. 2,5 In subluxation, the ulnar nerve moves onto the tip of the epicondyle during elbow flexion.…”

mentioning

confidence: 99%

“…Based on earlier reports in the literature, 4,5 we expected that the electrodiagnostic findings would be different between patients with (sub)luxation and those without. However, only the FDI CMAPs elicited at the wrist and above the elbow, and the FDI and ADM CMAPs elicited below the elbow were significantly lower in patients with (sub)luxation.…”

mentioning

confidence: 99%

“…Moreover the same investigators found (pseudo-)conduction blocks in all healthy controls with ulnar nerve dislocation when they used short-segment nerve conduction studies. 4 These ''blocks'' disappeared when shortsegment conduction studies were performed along the actual course of the dislocated ulnar nerve. Therefore, we expected to find a higher percentage of cases with pseudo-conduction block in the group of patients with (sub)luxation than in the group without.…”

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Sonographic incidence of ulnar nerve (sub)luxation and its associated clinical and electrodiagnostic characteristics

et al. 2013

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“…However, the course of a nerve in the body may be convoluted, and the segment across the elbow is a hypermobile area due to the movement of the elbow joint, 1,2 distance measurements using only surface landmarks often do not reflect the true pathway of the nerve.…”

Section: Introductionmentioning

confidence: 99%

Nerve length measurement method in a radial motor nerve conduction study

Kim

Seok

et al. 2017

Ann Clin Neurophysiol

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Background: Previous studies of radial nerve conduction study (NCS) did not present how to measure the length of the radial nerve across the elbow, and did not even mention how to manage the spiral course of the nerve. This study aimed to applicate the most reliable method to measure the length of the radial nerve during NCS. Methods: Three points (A, B, and C) were determined along the relatively straight course of the radial nerve. The distance was measured using three different methods: L1) straight distance corresponding to the A-C distance, L2) sum of the distances corresponding to the A-B-C distance, L3) based on the L2, but the elbow is flexed at a 45° angle. We compared the three methods of distance measurement and the calculated nerve conduction velocities (V1, V2, and V3) in normal healthy subjects. Results: 19 normal participants were enrolled. The mean value for method L1, L2 and L3 were 22.5 ± 1.8 cm, 24.0 ± 2. 1 cm, and 23.2 ± 2. 1 cm (p < 0.001). Calculated conduction velocities using those distance measurement methods as follows (p < 0.001): V1 (60.9 ± 2.7 m/s), V2 (64.6 ± 3.3 m/s), and V3 (63.4 ± 3.9 m/s). V2 was significantly greater than V1 and V3 (p < 0.001, p = 0.010, respectively). Conclusions:The distance measurement using a stopover point near the lateral epicondyle between two stimulus points in position of a fully extended elbow with forearm pronation is the most appropriate posture for radial motor NCS. Jae-Gyum Kim, et al. Measuring the length of the radial nerve INTRODUCTIONWe often calculate the nerve conduction velocity by measuring the distance between two points on a nerve, which represent the length of the nerve during a nerve conduction study (NCS). However, the course of a nerve in the body may be convoluted, and the segment across the elbow is a hypermobile area due to the movement of the elbow joint, 1,2 distance measurements using only surface landmarks often do not reflect the true pathway of the nerve.As the ulnar nerve which is recommended a flexed elbow posture for NCS due to tortuous course at the elbow with extended posture, 3-6 the radial nerve also has a convoluted course. Several previous studies have investigated the appropriate technique for performing an NCS for the radial nerve across the elbow with normal subjects. These studies suggested that a fully pronated posture should be used to locate the medial position of the radial nerve 7,8 and that a fully extended elbow posture should be used to straightened the radial nerve. However, those studies did not present how to measure the length of the radial nerve across the elbow, and did not even mention how to manage the spiral course of the nerve. 9-11We have recently published a study that suggested a length measurement method using 10 cadavers.12 However, the study was limited to cadaveric investigation, so we needed to prove that the suggested method is appropriate in clinical practice. We performed this study to apply the most appropriate method for a NCS of the radial nerve across the elbow in normal healthy ...

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Pearls & Oy-sters: False positives in short-segment nerve conduction studies due to ulnar nerve dislocation

Cited by 28 publications

References 10 publications

Avoiding false‐negative nerve conduction study in ulnar neuropathy at the elbow

Avoiding false‐negative nerve conduction study in ulnar neuropathy at the elbow

Sonographic incidence of ulnar nerve (sub)luxation and its associated clinical and electrodiagnostic characteristics

Nerve length measurement method in a radial motor nerve conduction study

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