Risk assessment of dorsal scapular nerve injury in the medial scapular area associated with upper extremity position: An ultrasonographic study.

INTRODUCTION/AIMS: Injuries to the dorsal scapular nerve (DSN) in the interscapular region are relatively uncommon. Physicians may therefore underestimate the risk of damage to the DSN during procedures. The aim of this study was to identify the topographic position of the DSN in the interscapular region and to identify injection positions for the upper extremities that minimize the risk of damage to the DSN during procedures. METHODS: The positional relationships between the DSN and scapula were quantified by ultrasonography in 46 healthy volunteers. The distances between the medial scapular line and DSN and the DSN depths from the surface in Zones 1 (the superior angle), 2 (the scapular spine), and 3 (between the scapular spine and inferior angle) were measured in the anatomical and contralateral shoulder touch positions (positions 1 and 2, respectively). RESULTS: The DSN was located further away from the medial border of the scapula and closer to the skin in position 2 than in position 1. The horizontal distance of the DSN in Zone 2 differed significantly between the two positions (0.85 ± 0.38 vs 1.23 ± 0.38, P < .001). The results suggest a safe area as just medial to the medial scapular border in Zone 2 in position 2. The safety margin should be considered at least 1.5 cm medial to the medial border of the scapula in Zone 3 in position 1. DISCUSSION: Performing invasive procedures in the interscapular region, appropriate individualized positioning may reduce the risk of DSN injury.

Independent effect of cardiometabolic syndromes and depression on dementia in Parkinson's disease: A 12-year longitudinal follow-up study of a nationwide cohort.

BACKGROUND: We aimed to investigate the incidence rate of Parkinson's disease dementia (PDD) according to age and disease duration by sex. Furthermore, we explored the effect of each cardiometabolic syndrome and depression on the incidence of PDD. METHODS: Using data from the Korean National Health Insurance Service, 79,622 patients with de novo Parkinson's disease (PD) aged ≥40 years between January 2002 and December 2010 were followed to December 2019. We analyzed the incidence of PDD according to age at PD diagnosis and disease duration. To determine cardiometabolic syndromes and depression that affected PDD, we used Fine and Gray competing regression after controlling for age and sex. RESULTS: During the 12.5-year follow-up period, the incidence of PDD increased with age at PD diagnosis (0.81-45.31 per 1000 person-years among those aged 40-44 and over 80 years, respectively) and longer disease duration (22.68 per 1000 person-years in 1-2 years to 34.16 per 1000 person-years in 15-16 years). Hypertension (subdistribution hazard ratio [SHR] = 1.11; 95% confidence interval [CI] 1.07-1.16), diabetes (SHR = 1.09; 95% CI 1.05-1.14), dyslipidemia (SHR = 1.15; 95% CI 1.11-1.20), and depression (SHR = 1.36; 95% CI 1.30-1.41) independently increased the risk for PDD. CONCLUSIONS: Our findings provide insights into cardiometabolic syndromes as modifiable risk factors for incident PDD. Furthermore, our results will help in designing public health policies with respect to controlling cardiometabolic syndromes and depression to prevent incident PDD in patients with PD.

Feasibility of artificial intelligence assisted quantitative muscle ultrasound in carpal tunnel syndrome.

BACKGROUND: In case of focal neuropathy, the muscle fibers innervated by the corresponding nerves are replaced with fat or fibrous tissue due to denervation, which results in increased echo intensity (EI) on ultrasonography. EI analysis can be conducted quantitatively using gray scale analysis. Mean value of pixel brightness of muscle image defined as EI. However, the accuracy achieved by using this parameter alone to differentiate between normal and abnormal muscles is limited. Recently, attempts have been made to increase the accuracy using artificial intelligence (AI) in the analysis of muscle ultrasound images. CTS is the most common disease among focal neuropathy. In this study, we aimed to verify the utility of AI assisted quantitative analysis of muscle ultrasound in CTS. METHODS: This is retrospective study that used data from adult who underwent ultrasonographic examination of hand muscles. The patient with CTS confirmed by electromyography and subjects without CTS were included. Ultrasound images of the unaffected hands of patients or subjects without CTS were used as controls. Ultrasonography was performed by one physician in same sonographic settings. Both conventional quantitative grayscale analysis and machine learning (ML) analysis were performed for comparison. RESULTS: A total of 47 hands with CTS and 27 control hands were analyzed. On conventional quantitative analysis, mean EI ratio (i.e. mean thenar EI/mean hypothenar EI ratio) were significantly higher in the patient group than in the control group, and the AUC was 0.76 in ROC analysis. In the analysis using machine learning, the AUC was the highest for the linear support vector classifier (AUC = 0.86). When recursive feature elimination was applied to the classifier, the AUC value improved to 0.89. CONCLUSION: This study showed a significant increase in diagnostic accuracy when AI was used for quantitative analysis of muscle ultrasonography. If an analysis protocol using machine learning can be established and mounted on an ultrasound machine, a noninvasive and non-time-consuming muscle ultrasound examination can be conducted as an ancillary tool for diagnosis.

Ultrasound assessment of medial crural cutaneous nerve and infrapatellar branch and of the saphenous nerve: establishing a safety zone for preventing nerve injury in knee surgery and injections.

PURPOSE: Our study aimed to illustrate the positional relationship of the two branches of the saphenous nerve: the infrapatellar branch of the saphenous nerve (IPBSN) and medial crural cutaneous nerve (MCCN), as well as the anatomical landmarks using high-resolution ultrasound (HRUS) to help prevent iatrogenic nerve injury. METHODS: We used HRUS to explore the positional relationships among the anatomical landmarks, IPBSN, and MCCN in 40 knees of 20 participants. The distances from these branches to key reference points were recorded. Using the ultrasound caliper mode, we measured the depth from the skin surface to the nerves at four distinct points. RESULTS: The average distances between IPBSN and medial border of patella (MBP) and IPBSN and medial border of patellar ligament (MBPL) were 47 ± 7 mm and 42 ± 9 mm, respectively. MCCN showed mean distances of 94 ± 9 mm and 96 ± 9 mm to MBP and MBPL, respectively. The mean distance from the upper edge of pes anserine to IPBSN at the patellar apex (PA) level was 24 ± 10 mm and to MCCN was 34 ± 9 mm. CONCLUSION: We used high-resolution ultrasound to evaluate IPBSN and MCCN and their positions relative to anatomical landmarks. The study results offer valuable insights into the course of these nerves, which can help establish a safety zone to prevent accidental nerve injuries during knee surgeries and injections.

Mass effect of the distal triceps brachii muscle on ulnar nerve movement during elbow flexion.

INTRODUCTION/AIMS: Hypertrophic triceps brachii contributes to ulnar nerve movement, but the location of the mass effect of the triceps brachii muscle is not known. In this study we aimed to determine the mass effect of the distal medial head of the triceps brachii (DMTB) muscle on ulnar nerve movement. METHODS: In 48 arms, movement of the ulnar nerve at the medial epicondyle and muscle thickness (medial and long head of the triceps brachii [MLTB], medial head of the triceps brachii [MTB], DMTB, and biceps brachii [BB]) were measured using ultrasonography. RESULTS: Ulnar nerve movement at the elbow was consistently correlated with the DMTB muscle thickness (horizontal ulnar nerve movement at the elbow [HM] / vertical ulnar nerve movement at the elbow [VM] with 90° elbow flexion: r = 0.668 / r = 0.313, HM/VM with full elbow flexion: r = 0.481 / r = 0.391). With multiple linear regression, the DMTB was the most important muscle with regard to contribution of thickness to ulnar nerve movement. Individuals with partial and complete dislocation showed a thicker DMTB than those without dislocation. DISCUSSION: Our data suggest that the mass effect of the triceps brachii muscle is exerted primarily by its distal portion. When ulnar nerve dislocation is observed, thickness and anatomical variation of DMTB in the retrocondylar area during elbow flexion should be assessed.

Ultrasonographic anatomy of posterior antebrachial cutaneous nerve in healthy subjects.

INTRODUCTION/AIMS: The posterior antebrachial cutaneous nerve (PACN) is one of the cutaneous branches of the radial nerve, and receives sensory input from the posterior arm and forearm. The aim of this study is to describe the ultrasonographic anatomy of the PACN. METHODS: PACN and its branches were scanned using ultrasonography in 30 healthy volunteers. The distances between the epicondylar line and the bifurcation site of each branch of PACN (A) point of separation of the radial nerve and the PACN, (B) point of separation of the anterior and posterior divisions, (C) point of bifurcation of the posterior division into the epicondylar and anconeus branches), cross-sectional areas and depths from the skin surface to each nerve at positions A, B, and C were measured. RESULTS: The mean distance from the epicondylar line to A, B, and C was 10.01 ± 0.82 cm, 7.46 ± 0.98 cm, and 4.02 ± 1.16 cm, respectively. The mean depth from the skin surface at A, B, and C was 1.00 ± 0.19 cm, 0.72 ± 0.19 cm, and 0.51 ± 0.12 cm, respectively. DISCUSSION: Ultrasonographic visualization of the PACN and its major branches was feasible. The reference values in this study may be helpful for more accurate sonographic assessment and electrophysiologic study, and contribute to safer interventions around the elbow region.

Risk Analysis of Needle Injury to the Long Thoracic Nerve during Ultrasound-Guided C7 Selective Nerve Root Block.

Background and Objectives: Ultrasound (US)-guided cervical selective nerve root block (SNRB) is a widely used treatment for upper limb radicular pain. The long thoracic nerve (LTN) passes through the middle scalene muscle (MSM) at the C7 level. The needle trajectory of US-guided C7 SNRB pierces the MSM, therefore indicating a high probability of injury to the LTN. We aimed to identify the LTN and to investigate the risk of needle injury to the nerve during US-guided C7 SNRB. Materials and Methods: This retrospective observational study included 30 patients who underwent US-guided SNRB at the C7 level in a university hospital. We measured the maximal cross-sectional diameter (MCSD) of the LTN and cross-sectional area (CSA) of the C7 nerve root and assessed the injury risk of LTN during US-guided C7 SNRB by simulating the trajectory of the needle in the ultrasound image. Results: The LTN was detectable in all the cases, located inside and outside the MSM in 19 (63.3%) and 11 (36.7%) of cases, respectively. The LTN's mean MCSD was 2.10 mm (SD 0.13), and the C7 root's CSA was 10.78 mm2 (SD 1.05). The LTN location was within the simulated risk zone in 86.7% (26/30) of cases. Conclusion: Our findings suggest a high potential for LTN injury during US-guided C7 SNRB. The clear visualization of LTNs in the US images implies that US guidance may help avoid nerve damage and make the procedure safer. When performing US-guided C7 SNRB, physicians should take into consideration the location of the LTN.

Sonoanatomy of the deep branch of the ulnar nerve.

INTRODUCTION: This study evaluated the sonoanatomy of the deep motor branch of the ulnar nerve (DBUN) using high-resolution ultrasonography (HRUS). METHODS: In 60 wrists of 30 healthy adults, the gross course, cross-sectional area (CSA), and diameter of the DBUN were observed by HRUS (frequency band 3-16 MHz). Its course was assessed by using the distance from anatomical landmarks and depth from the skin. RESULTS: The DBUN was found in all subjects with HRUS, and it branched off from the ulnar nerve before reaching the hamate bone. At the hook-of-hamate level, the mean DBUN CSA was 1.5 ± 0.2 mm2 , and the mean diameter was 1.5 ± 0.2 mm. The mean distance from the hamate hook to the DBUN was 5.4 ± 1.0 mm, and the mean depth from the skin was 8.6 ± 1.6 mm. DISCUSSION: Sonoanatomy of the DBUN obtained from HRUS may be useful in detecting or preventing DBUN lesions.

Pilot study: Differences in echo intensity ratios between ulnar and median innervated muscles in ulnar neuropathy.

BACKGROUND: This study evaluated muscle echo intensity (EI) ratio in patients with ulnar neuropathy at the elbow (UNE) and healthy controls. METHODS: In this prospective study, 28 patients with electrodiagnostically confirmed unilateral UNE and 12 healthy controls were ultrasonographically assessed for EI ratios of the hypothenar and thenar muscles. The affected and unaffected hands between the UNE patients and controls and patient subgroups (subdivided according to electrodiagnostic severity) were compared to determine any significant differences. RESULTS: In patients with UNE, the EI ratio of the hypothenar to thenar muscles was significantly higher for the affected side than for the unaffected side (1.08 ± 0.11 and 0.97 ± 0.18, respectively) or the control group (0.95 ± 0.05). A significant difference in the EI ratio was observed among the subgroups (mild vs. severe subgroup, P < 0.01). CONCLUSIONS: Ultrasonographic EI measurement may be a useful parameter in the evaluation and screening of UNE.

Ultrasonographic measurement of the cross-sectional area of the axillary nerve.

INTRODUCTION: The objectives of this study were to determine normal reference values for ultrasonographic measurement of the cross-sectional area (CSA) of the axillary nerve and to standardize the measurement methods. METHODS: Sixty healthy volunteers were evaluated. Ultrasonography was performed with the shoulder positioned in 100°-120° abduction and 90° external rotation. The CSA of the axillary nerve was measured bilaterally. RESULTS: The normal CSA of the right axillary nerve was 2.9 ± 1.1 mm2 . The side-to-side discrepancy was 22.8% ± 17.8%. DISCUSSION: These reference values may be helpful for investigating pathologies involving the axillary nerve.

Muscle echogenicity ratio can indicate severity of carpal tunnel syndrome.

INTRODUCTION: The purpose of this study was to investigate the usefulness of the echogenicity (EI) ratio of the thenar to hypothenar muscle measured using ultrasonography in assessing the severity of carpal tunnel syndrome (CTS). METHODS: Fifty-nine hands of 30 patients electrodiagnostically confirmed as having CTS were classified into 3 subgroups (mild, moderate, and severe). The EI of the thenar and hypothenar muscles was measured with ultrasonography, and the EI ratio was calculated in the patients and 13 normal participants (26 hands). RESULTS: The average EI ratio was higher in the CTS group than in the control group. We also found a positive correlation between the severity of CTS and a high EI ratio measured with ultrasonography. DISCUSSION: The EI ratio of the thenar to hypothenar muscle is a useful parameter that can indicate the severity of CTS. Muscle Nerve 58: 304-306, 2018.

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.

Effect of finger motion on transverse median nerve movement in the carpal tunnel.

INTRODUCTION: We used ultrasonography (US) to investigate the effects of finger motion on movement of the median nerve in patients with carpal tunnel syndrome (CTS) and the correlation between these US parameters and CTS severity. METHODS: Ultrasonographic measures were performed in 23 control wrists and 22 CTS wrists in women. During first through third finger flexion and grip motion, median nerve movements were obtained using US and a tracing program. RESULTS: Nerve movements during third finger flexion in the dorsopalmar axis and grip motion in both axes, and during second finger flexion in the radioulnar axis, differed significantly between the control and CTS groups. US parameters correlated negatively with cross-sectional area. CONCLUSIONS: This study shows that transverse median nerve movements decreased during grip using US and correlated negatively with CTS severity. Muscle Nerve, 2016 Muscle Nerve 54: -, 2016 Muscle Nerve 54: 738-742, 2016.

Ultrasound-Guided Cervical Nerve Root Block: Does Volume Affect the Spreading Pattern?

OBJECTIVE: Ultrasound-guided cervical nerve root block (US-CRB) is considered a safe and effective method for the treatment of radicular pain. However, previous studies on the spreading pattern of injected solution in US-CRB have reported conflicting results. The aim of this study was to investigate the spreading pattern in relation to injection volume. DESIGN: An institutional, prospective case series. SETTING: A university hospital. SUBJECTS: Fifty-three patients diagnosed with mono-radiculopathy in C5, 6, or 7. METHODS: US-CRB with fluoroscopic confirmation was performed. After the cervical roots were identified in ultrasound imaging, a needle was gently introduced toward the posterior edge of the root using an in-plane approach. The spread of 1 mL and 4 mL contrast medium, each injected in the same needle position, was examined with anteroposterior and lateral fluoroscopic views. After contrast injection, a mixture of local anesthetic and corticosteroid was injected. Clinical outcome was assessed using a numeric rating scale before and 2 weeks after the procedure. RESULTS: Contrast medium did not spread into the epidural space in any patients with 1 mL contrast medium injection, but it did spread into the intraforaminal epidural space in 13 patients (24.5%) with 4 mL. Pain improved in all patients. There was no significant difference in pain relief according to the spreading pattern. CONCLUSION: The spreading pattern of injected solution in US-CRB could be partially affected by the injectant volume. However, further studies are needed to assess the importance of other factors, such as needle position and physiological effects.

Magnetic resonance elastography (MRE) for measurement of muscle stiffness of the shoulder: feasibility with a 3 T MRI system.

BACKGROUND: Magnetic resonance elastography (MRE) at 3 T MR has the potential to improve the objective detection of skeletal muscle stiffness. PURPOSE: To determine the feasibility of MRE using 3 T MR for measurement of the stiffness of shoulder muscles in subjects. MATERIAL AND METHODS: This study prospectively evaluated 16 healthy subjects (mean age, 29.8 years; range, 25-51 years). MRE was acquired with 3 T MR through the use of a 2D-gradient-echo-based MRE sequence at two different excitation frequencies (90 and 120 Hz). The mean stiffness values (MSV) of the trapezius and infraspinatus muscles were measured by two radiologists. Differences between the MSV in the x, y, and z motion-sensitization directions were assessed. Inter-observer agreement was also measured. RESULTS: The MSV of the trapezius muscle were 2.72 kPa ± 0.6 (SD) at 90 Hz and 4.66 kPa ± 1.2 at 120 Hz, while the MSV for the infraspinatus muscle were 3.2 kPa ± 0.52 at 90 Hz and 4.38 kPa ± 0.92 at 120 Hz. The MSV for both muscles were significantly higher at 120 Hz than at 90 Hz (P < 0.05). The MSV in the three different directions were significantly different from each other in the infraspinatus muscle (P < 0.05). Levels of inter-observer agreement regarding MSV were good to excellent for both the trapezius (intraclass correlation coefficient [ICC] = 0.979-0.996) and infraspinatus muscles (ICC = 0.614-0.943). CONCLUSION: MRE at 3 T is a feasible technique for the evaluation of shoulder muscle stiffness. Extended application of skeletal muscle MRE at 3 T will contribute to the evaluation and treatment of skeletal muscle disorders.

Effect of Carpal Tunnel Syndrome on the Ulnar Nerve at the Wrist: Sonographic and Electrophysiologic Studies.

OBJECTIVES: The aim of this study was to compare the ulnar nerve at the wrist by sonographic and electrophysiologic studies between patients with carpal tunnel syndrome and control participants and to verify the effect of carpal tunnel syndrome of the ulnar nerve at the wrist. METHODS: Forty-two hands of patients with carpal tunnel syndrome and 37 hands of control participants were examined. Electrophysiologic studies of the ulnar nerve were done in all participants. The cross-sectional areas of the median and ulnar nerves at the wrist were evaluated by sonography. Fifteen hands of patients with carpal tunnel syndrome who underwent carpal tunnel release were also evaluated by sonography after the operation. RESULTS: The ulnar nerve cross-sectional area of the patients with carpal tunnel syndrome (mean ± SD, 5.16 ± 1.04 mm(2)) was significantly larger than that of the controls (3.56 ± 0.52 mm(2); P < .0001). After release of the transverse carpal ligament, the cross-sectional area of the ulnar nerve was significantly smaller than the size measured prior to surgery (P < .0001). The cross-sectional area of the median nerve was significantly correlated with that of the ulnar nerve (P < .05). However, no statistically significant difference was found between the patients with carpal tunnel syndrome and controls in ulnar nerve conduction. There were no statistically significant differences in nerve conduction study results or cross-sectional area of the ulnar nerve between patients with carpal tunnel syndrome with and without extramedian symptoms. CONCLUSIONS: The cross-sectional areas of the ulnar and median nerves at the wrist are increased in patients with carpal tunnel syndrome. Also, the cross-sectional area of the ulnar nerve is decreased after carpal tunnel release.

Ultrasound-Guided Lower Cervical Nerve Root Injectate Volumes Associated With Dorsal Root Ganglion and Epidural Spread.

OBJECTIVES: We aimed to estimate the spread of injections for ultrasound-guided cervical nerve root blocks and to determine the optimal injectate volume required in this procedure. METHODS: A total of 32 ultrasound-guided injections (C5-C8) were made in 4 fresh cadavers. The target on each cervical root was the space between the posterior tubercle and the cervical root at the most proximal location possible on the sonogram. After ultrasound-guided needle insertion, 0.5 mL of a contrast medium was injected 4 times. The dye flow patterns were confirmed with fluoroscopy each time, and we recorded whether the contrast medium reached the dorsal root ganglion level or the epidural space. After the injections, the needle tip location was determined by computed tomography and image reconstruction. RESULTS: All injections produced typical neurograms. The contrast medium reached the dorsal root ganglion in 29 of 32 (90.6%) injections (mean ± SD, 0.84 ± 0.42 mL of contrast medium) and the epidural space in 10 of 32 (31.3%) injections (1.30 ± 0.54 mL of contrast medium). The mean distance between the needle tip and neural foramen was 9.64 ± 3.68 mm, and this distance correlated positively with the volume of contrast medium necessary to reach the dorsal root ganglion or the epidural space. CONCLUSIONS: Ultrasound-guided cervical nerve root blocks show potential utility for targeting an anesthetic into the cervical root area. This study may be helpful for deciding the most appropriate volume for the procedure.

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.

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

OBJECTIVES: 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. METHODS: We studied 31 hands of healthy control participants (n = 16; mean age ± SD, 60.25 ± 14.67 years) and 81 hands of patients with PD (n = 42; 64.95 ± 11.13 years). Motor symptoms were measured by the Unified Parkinson's Disease Rating Scale III. Median nerve conduction studies and sonographic cross-sectional area measurements were performed in all participants. RESULTS: The median nerve cross-sectional area in patients with PD (10.71 ± 2.79 mm(2)) was significantly larger than that in the control group (7.40 ± 1.05 mm(2); P < .05). However, there was no significant difference in median nerve electrodiagnostic findings between the PD and control groups. The median nerve cross-sectional area was associated with the severity of the tremor but not with the Unified Parkinson's Disease Rating Scale motor score. CONCLUSIONS: Tremor in PD is associated with median nerve enlargement but not with impairment of median nerve conduction.