Sun Jae Won

Median nerve changes following steroid injection for carpal tunnel syndrome.

Introduction: Neuromuscular ultrasound is a painless, radiation‐free, high‐resolution imaging modality for assessment of the peripheral nervous system. The purpose of this study was to use neuromuscular ultrasound to assess the changes that occur in the median nerve after steroid injection for carpal tunnel syndrome (CTS). Methods: Ultrasound and nerve conduction studies were performed at baseline and 1 week, 1 month, and 6 months after steroid injection in 19 individuals (29 wrists) with CTS. Results: Significant changes were noted in median nerve cross‐sectional area (P < 0.001), mobility (P = 0.001), and vascularity (P = 0.042) at the distal wrist crease after steroid injection, and the nerve cross‐sectional area correlated with symptom score and electrodiagnostic parameters. Changes in the ultrasonographic parameters were seen within 1 week of injection. Conclusions: These findings suggest neuromuscular ultrasound is potentially helpful for the assessment of individuals undergoing treatment for CTS, as typical changes can be expected after successful treatment injection. Muscle Nerve 44: 25–29, 2011

Reference values for nerve ultrasonography in the upper extremity

The aims of this study were to identify factors affecting the measurement of nerve cross‐sectional area (CSA) and to establish normal reference values for nerve ultrasonography of the upper extremity.

Carpal tunnel syndrome: Clinical, electrophysiological, and ultrasonographic ratio after surgery

Introduction: The aim of this study was to improve our understanding of the pathophysiology of carpal tunnel syndrome (CTS) and to highlight the ultrasonographic cross‐sectional area (CSA) ratio as a tool for assessing outcomes by investigating postoperative changes. Methods: Twenty‐four individuals with CTS were evaluated using the Boston questionnaire, nerve conduction studies, and ultrasound, preoperatively and at 3 weeks and 3 months postoperatively. Results: Improved symptom scores, decreased CSA, and decreased CSA ratio were observed in the first 3 weeks, but functional improvement was also observed after 3 weeks postoperatively. The ratios between the CSA at the sites of enlargement and unaffected areas correlated significantly with the Padua classification, although the coefficient was not superior to the coefficient of CSA at the maximal swelling site. Conclusions: Symptoms improved more rapidly than function after surgery. Measurement of the ultrasonographic CSA ratio may provide clinicians with a useful assessment tool after surgery. Muscle Nerve, 2012

Measurement of cross-sectional area of cervical roots and brachial plexus trunks.

Introduction: The aim of this study was to determine normal reference values for cross‐sectional area (CSA) and the correlation between demographic factors and CSA in the cervical roots and brachial plexus trunks using ultrasonography. Methods: Ninety‐five age‐matched healthy individuals were studied. Ultrasonographic tests were performed via nerve tracing from the cervical root to the brachial plexus trunk. The CSA of each nerve was measured in the C5–8 ventral roots and brachial plexus (trunk level). Results: Normal values of each cervical root were: C5, 5.66 ± 1.02 mm2; C6, 8.98 ± 1.65 mm2; C7, 10.43 ± 1.86 mm2; and C8, 10.76 ± 2.02 mm2. Values for the brachial plexus were: upper trunk, 16.70 ± 2.88 mm2; middle trunk, 14.01 ± 2.70 mm2; and lower trunk, 13.75 ± 2.57 mm2. The side‐to‐side discrepancy was 11.91 ± 11.11%. Body mass index (BMI) and height correlated frequently with nerve CSA. Conclusions: These reference values may be helpful in investigating pathologies involving the cervical area. Muscle Nerve 46: 711–716, 2012

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

Ulnar nerve displacement at the elbow causes overestimation of nerve conduction velocity. We hypothesized that this overestimation may cause false‐negative results when the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) diagnostic criteria are used.

Cross-sectional area reference values of nerves in the lower extremities using ultrasonography.

Introduction: Cross‐sectional area (CSA) reference values of lower extremity nerves using ultrasonography have only been reported in a few studies and have been limited to white populations. Methods: For this study, 94 healthy Korean volunteers were recruited for measurement of the CSA at 7 sites of lower extremity nerves. The side‐to‐side difference in CSA was calculated for each nerve, and reference ranges were derived. External validity evaluation for the reference values was performed with 10 newly recruited volunteers at a different institution. Results: Nerve CSA was correlated significantly with body mass index, weight, and height; however, the absolute value of the side‐to‐side difference had no significant correlation with demographic factors. The external validity was adequate for all sites, ranging from 80% to 100%. Conclusions: The lower extremity nerve CSA values obtained in this study may provide normal reference values for the Asian population. Muscle Nerve 50: 564–570, 2014

Ultrasonographic Evaluation of Needle Electromyography Insertion Into the Tibialis Posterior Using a Posterior Approach

OBJECTIVE To estimate the safety window for needle insertion in the posterior approach to the tibialis posterior by ultrasonography, particularly in a clinical setting. DESIGN Cross-sectional study. SETTING University hospital. PARTICIPANTS Healthy volunteers (108 legs, from 22 men and 32 women). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Distance between the tibia and neurovascular bundles in the posterior aspect of the tibia on a transverse ultrasonographic scan. RESULTS The safety window at the midpoint was significantly larger than the upper third (0.62-2.16 cm, average 1.47 ± 0.38 cm vs 0.51-1.62 cm, average 1.16 ± 0.31 cm). The depth at the midpoint was significantly more shallow than the upper third (1.57-3.16 cm, average 2.31 ± 0.34 cm vs 1.76-3.66 cm, average 2.52 ± 0.38 cm). Body weight, height, tibial length, and leg circumference showed positive correlation with the safety window at both points. CONCLUSIONS The midpoint may be more favorable than the upper third for needle insertion to the tibialis posterior with a posterior approach.

Usefulness of Ultrasonography to Predict Response to Injection Therapy in Carpal Tunnel Syndrome

Objective To verify the feasibility of initial parameters of ultrasonography or electromyography for the prediction of effect after steroid injection therapy in a carpal tunnel syndrome (CTS) patient. Method We recruited individuals with clinical and electrodiagnostic evidence of CTS. Results from the Boston self-assessment questionnaire, median motor and sensory nerve conduction studies, and median nerve ultrasonography were evaluated at baseline, 1 month, and 6 months after injection. Evaluation of median nerve ultrasonography parameters included measurements taken at the maximal swelling point (MS), 2 cm proximal from MS (2MS), and 12 cm proximal from MS (12MS), and its ratio (MS/12MS, 2MS/12MS) was calculated. The correlation between improvement of the symptom score after treatment and baseline parameters was estimated. Results Fourteen individuals (14 women, mean age 53.8 years) with 22 affected wrists were enrolled. After steroid injection therapy, clinical and electromyographic parameters showed significant improvements at 1 month or 6 months after injection, and ultrasonographic parameters showed significant changes in maximal area and area ratio (MS/12MS) of the median nerve. Symptom score improvement showed a positive correlation in the initial 2MS and ratio of 2MS/12MS after 6 months (p<0.05). Conclusion Most of the improvements occurred during the first month after injection and lasted up to 6 months. The initial median nerve swelling and its ratio may be a useful predictor of response after steroid injection.

Is median nerve enlargement at the wrist associated with tremor in Parkinson disease

Tremor is one of the cardinal features of Parkinson disease (PD) and may cause cumulative trauma‐related injury to nerves of the hands. The aim of this study was to assess the electrodiagnostic and sonographic features of patients with PD and to assess the effect of tremor in PD on the median nerve.

Approach for needle insertion into the tibialis posterior: An ultrasonography study.

Introduction: To avoid neurovascular damage by needle electrode insertion into the tibialis posterior, we used ultrasonography to determine the proper insertion point based on anatomic landmarks. Methods: Using ultrasonography, the safety window, the corrected safety window, and the depth of the tibialis posterior were measured at 4 points (the upper third and midpoint of the tibia using anterior and posterior approaches) in healthy volunteers. Results: The safety window at the midpoint for the posterior approach was significantly larger than at the other points. The corrected safety window could be defined only at the upper third for the anterior approach and at the midpoint for the posterior approach. Conclusions: Among the 4 points used for needle insertion into the tibialis posterior, the midpoint by the posterior approach may be the most favorable insertion point. The upper third may be better for the anterior approach. Muscle Nerve 53: 528–531, 2016