Objective: To compare transverse and longitudinal safe zones using ultrasonography between healthy individuals and patients with carpal tunnel syndrome (CTS). Methods: This was a prospective observational case-control study. Forty wrists from 20 healthy individuals and 40 wrists from 24 patients with CTS were examined. Patients with CTS were classified into three groups (mild, moderate, and severe CTS) based on electrodiagnostic findings. Using ultrasonography, we measured the distance between the median nerve and ulnar vessels to identify the transverse safe zone, and between the distal flexor retinaculum and superficial palmar artery arch to identify the longitudinal safe zone. Results: The transverse and longitudinal safe zones were significantly different between participants with CTS and those without CTS. The transverse safe zone significantly differed between the mild and severe CTS groups, while the longitudinal safe zone was not significantly different between the groups. The cross-sectional area of the median nerve negatively correlated with the transverse and longitudinal safe zones. Conclusion Transverse and longitudinal safe zones were narrower in patients with CTS than in the healthy group. A significant difference was observed between patients with mild CTS and those with severe CTS. Furthermore, the cross-sectional area of the median nerve was directly proportional to the degree of narrowing of the transverse and longitudinal safe zones.

Purpose: The aim of this study was to develop a neural network that accurately and effectively segments the median nerve in ultrasound (US) images. Methods: In total, 1,305 images of the median nerve of 123 normal subjects were used to train and evaluate the model. Four datasets from two measurement regions (wrist and forearm) of the nerve and two US machines were used. The neural network was designed for high accuracy by combining information at multiple scales, as well as for high efficiency to prevent overfitting. The model was designed in two parts (cascaded and factorized convolutions), followed by selfattention over scale and channel features. The precision, recall, dice similarity coefficient (DSC), and Hausdorff distance (HD) were used as performance metrics. The area under the receiver operating characteristic curve (AUC) was also assessed. Results: In the wrist datasets, the proposed network achieved 92.7% and 90.3% precision, 92.4% and 89.8% recall, DSCs of 92.3% and 89.7%, HDs of 5.158 and 4.966, and AUCs of 0.9755 and 0.9399 on two machines. In the forearm datasets, 79.3% and 87.8% precision, 76.0% and 85.0% recall, DSCs of 76.1% and 85.8%, HDs of 5.206 and 4.527, and AUCs of 0.8846 and 0.9150 were achieved. In all datasets, the model developed herein achieved better performance in terms of DSC than previous U-Net-based systems. Conclusion The proposed neural network yields accurate segmentation results to assist clinicians in identifying the median nerve.

Objective: To demonstrate the sonoanatomy of the medial antebrachial cutaneous nerve (MACN) in the elbow region using high-resolution ultrasonography (HRUS) to identify areas at a high risk of MACN injury. Methods: A total of 44 arms were included in the study. In the supine position, the participants’ arms were abducted 45° with the elbow fully extended. The MACN was visualized in the transverse view. The anterior branch of the MACN (ABMACN), posterior branch of the MACN (PBMACN), and location of the branching sites were determined. The distance between the ABMACN and superficial veins, including the basilic vein (BV) and median cubital veins (MCV) was measured. For the PBMACN, the distance to the ulnar nerve (UN) and to BV were measured. Results: The MACN was subdivided into 2.18±1.00 branches, including ABMACN and PBMACN. The ABMACN and PBMACN were subdivided into 1.60±0.78 and 1.07±0.25 branches, respectively. The branching point of the MACN was 8.40±2.42 cm proximal to the interepicondylar line (IEL). We demonstrated that the ABMACN is located close to the BV and MCV in the elbow region, and the PBMACN was located approximately 1 cm and 0.8 cm anterior to the UN and posterior to the BV at the IEL level, respectively. Conclusion Considering the location of the MACN, including ABMACN and PBMACN, clinicians can perform invasive procedures around the elbow region more carefully to lower the risk of MACN injury.

Objective: To assess the relevance of electrodiagnosis (EDX) in the cross-sectional area (CSA) of the nerve root of patients with cervical radiculopathy (CR) by using high-resolution ultrasonography (HRUS). Methods: The CSAs of the cervical nerve roots at C5, C6, and C7 were measured bilaterally using HRUS in 29 patients with unilateral CR whose clinical symptoms, magnetic resonance imaging (MRI) findings, and EDX results: corresponded with each other (CR-A group), and in 26 patients with unilateral CR whose clinical symptoms and MRI findings matched with each other but did not correspond with the EDX findings (CR-B group). Results The CSA of the affected side in each nerve root was significantly larger than that of the unaffected side in both the CR-A and CR-B groups. The side-to-side difference in the bilateral CSAs of the nerve root and the ratio of the CSAs between the unaffected and affected sides were statistically larger in the CR-A group than in the CR-B group. Conclusion The increased CSAs in the CR-A group reflect the physiological changes of the cervical nerve root, which is supported by the EDX findings.

Objective: To investigate the characteristics of the palmar cutaneous branch of the median nerve (PCBMN) in patient with carpal tunnel syndrome (CTS) using high-resolution ultrasound. Methods: Fourteen healthy volunteers (17 wrists) and 31 patients with CTS (41 wrists) were evaluated by high-resolution ultrasound. All patients were classified into three groups based on the electrophysiologic CTS impairment severity: mild, moderate, and severe. Using high-resolution ultrasound, the cross-sectional areas (CSAs) of the PCBMN were measured at the proximal wrist crease, bistyloid line, and distal wrist crease, and the largest CSA was defined as the maximal CSA. Results: The maximal CSA of the PCBMN of the control, mild, moderate, and severe CTS groups were 0.27±0.08, 0.30±0.07, 0.35±0.10, and 0.47±0.13 mm2, respectively. The maximal CSA of the PCBMN was significantly larger in the severe CTS group than in the other groups. Conclusion The PCBMN could be concomitantly affected in patients with severe CTS.

Objective: To assess the relevance of electrodiagnosis (EDX) in the cross-sectional area (CSA) of the nerve root of patients with cervical radiculopathy (CR) by using high-resolution ultrasonography (HRUS). Methods: The CSAs of the cervical nerve roots at C5, C6, and C7 were measured bilaterally using HRUS in 29 patients with unilateral CR whose clinical symptoms, magnetic resonance imaging (MRI) findings, and EDX results: corresponded with each other (CR-A group), and in 26 patients with unilateral CR whose clinical symptoms and MRI findings matched with each other but did not correspond with the EDX findings (CR-B group). Results The CSA of the affected side in each nerve root was significantly larger than that of the unaffected side in both the CR-A and CR-B groups. The side-to-side difference in the bilateral CSAs of the nerve root and the ratio of the CSAs between the unaffected and affected sides were statistically larger in the CR-A group than in the CR-B group. Conclusion The increased CSAs in the CR-A group reflect the physiological changes of the cervical nerve root, which is supported by the EDX findings.

Objective: To investigate the characteristics of the palmar cutaneous branch of the median nerve (PCBMN) in patient with carpal tunnel syndrome (CTS) using high-resolution ultrasound. Methods: Fourteen healthy volunteers (17 wrists) and 31 patients with CTS (41 wrists) were evaluated by high-resolution ultrasound. All patients were classified into three groups based on the electrophysiologic CTS impairment severity: mild, moderate, and severe. Using high-resolution ultrasound, the cross-sectional areas (CSAs) of the PCBMN were measured at the proximal wrist crease, bistyloid line, and distal wrist crease, and the largest CSA was defined as the maximal CSA. Results: The maximal CSA of the PCBMN of the control, mild, moderate, and severe CTS groups were 0.27±0.08, 0.30±0.07, 0.35±0.10, and 0.47±0.13 mm2, respectively. The maximal CSA of the PCBMN was significantly larger in the severe CTS group than in the other groups. Conclusion The PCBMN could be concomitantly affected in patients with severe CTS.

Objective: To investigate the diagnostic accuracy of two physical examinations (straight leg raise [SLR] and Bragard test) and electromyography (EMG) in patients with lumbosacral monoradiculopathy in acute and chronic state on confirmation of different diagnostic criteria (MRI vs MRI and diagnostic selective nerve root block [DSNRB]). Method: We identified 297 participants retrospectively from the departmental database. MRI evidence of L5 or S1 nerve root compression and a positive result in diagnostic SNRB served as reference standards. They were divided into two groups by the symptom duration: lasting more than 12 weeks in the chronic group and less than 12 weeks in the acute group. The diagnostic value of clinical tests and EMG were compared. Results: The clinical tests (SLR and Bragard test) done in acute stage on detection by MRI and DSNRB had the highest sensitivity (68%) compared to the chronic stage (63%), but sensitivity was low (57%) on confirmation of MRI alone. However, there was no significant difference on sensitivity and specificity of EMG regardless of reference standards and symptom duration. Electromyography was a significant predictor of neuropathic abnormalities on both acute (OR, 6.3; 95% CI, 2.4 to 16.7; p＜0.01) and chronic (OR, 6.8; 95% CI, 2.9 to 16.3; p＜0.01). Conclusion In general, individual physical tests are easy to do and a combination of those tests could be a sensitive indicator of L5 or S1 radiculopathy.Furthermore, the use of provocation tests could provide useful information, especially in proceeding therapeutic selective nerve root block.

Objective: To investigate the diagnostic accuracy of two physical examinations (straight leg raise [SLR] and Bragard test) and electromyography (EMG) in patients with lumbosacral monoradiculopathy in acute and chronic state on confirmation of different diagnostic criteria (MRI vs MRI and diagnostic selective nerve root block [DSNRB]). Method: We identified 297 participants retrospectively from the departmental database. MRI evidence of L5 or S1 nerve root compression and a positive result in diagnostic SNRB served as reference standards. They were divided into two groups by the symptom duration: lasting more than 12 weeks in the chronic group and less than 12 weeks in the acute group. The diagnostic value of clinical tests and EMG were compared. Results: The clinical tests (SLR and Bragard test) done in acute stage on detection by MRI and DSNRB had the highest sensitivity (68%) compared to the chronic stage (63%), but sensitivity was low (57%) on confirmation of MRI alone. However, there was no significant difference on sensitivity and specificity of EMG regardless of reference standards and symptom duration. Electromyography was a significant predictor of neuropathic abnormalities on both acute (OR, 6.3; 95% CI, 2.4 to 16.7; p＜0.01) and chronic (OR, 6.8; 95% CI, 2.9 to 16.3; p＜0.01). Conclusion In general, individual physical tests are easy to do and a combination of those tests could be a sensitive indicator of L5 or S1 radiculopathy.Furthermore, the use of provocation tests could provide useful information, especially in proceeding therapeutic selective nerve root block.

OBJECTIVE: To determine anatomical variation of the sural nerve (SN) by ultrasonography (US) and compare sensory nerve action potential (SNAP) of the SN obtained by a control method to that obtained with adjusted method using US. METHODS: Eighty legs of 40 healthy volunteers were enrolled. The location and formation of SN were investigated through US. Two methods of nerve conduction study (NCS) were then performed. In the control method, the cathode was placed 14 cm proximal to the lateral malleolus and the greatest SNAP amplitude was obtained by moving the cathode medially or laterally from just lateral to the calf-mid line. In adjusted NCS, the exact SN union site was stimulated in type 1. In other SN types, the stimulation was done directly over the nerve and the distance from the lateral malleolus was set to be 14 cm. RESULTS: It was found that 73.8% of the SNs were type 1, 22.5% were direct continuation of MSCN (type 2), and 3.8% were MSCN and LSCN without communicating (type 4). However, type 3 was not found. The union point in type 1 SN was 12.6±2.5 cm proximal to the lateral malleolus and 1.4±0.7 cm lateral to the calf-midline. After stimulation adjustment, SNAP amplitude in type 1 SN was significantly increased (20.7±5.5 μV vs. 27.1±6.7 μV). CONCLUSION: Anatomical variation of SN and its location were verified by US. US provides additional information for conducting sural NCS and helps obtain more accurate results.
Action Potentials ; Electrodes ; Healthy Volunteers ; Leg ; Methods ; Neural Conduction ; Sural Nerve ; Ultrasonography