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To define the anatomy of the lateral antebrachial cutaneous nerve (LABCN) and the cephalic vein (CV) in the anterior forearm region of living humans using ultrasonography for preventing LABCN injury during cephalic venipuncture.
Thirty forearms of 15 healthy volunteers were evaluated using ultrasonography to identify the point where the LABCN begins to contact with the CV, and the point where the LABCN separates from the CV. The LABCN pathway in the forearm in relation to a nerve conduction study was also evaluated.
The LABCNs came in contact with the CV at a mean of 0.6±1.6 cm distal to the elbow crease, and separated from the CV at a mean of 7.0±3.4 cm distal to the elbow crease. The mean distance between the conventionally used recording points (point R) for the LABCN conduction study and the actual sonographic measured LABCN was 2.4±2.4 mm. LABCN usually presented laterally at the point R (83.3%).
The LABCN had close proximity to the CV in the proximal first quarter of the forearm. Cephalic venipuncture in this area should be avoided, and performed with caution if needed.
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To investigate the contributing factors of carpal tunnel syndrome (CTS), electrodiagnostic and ultrasonographic findings of median nerve, and median nerve change after exercise in wheelchair basketball (WCB) players.
Fifteen WCB players with manual wheelchairs were enrolled in the study. Medical history of the subjects was taken. Electrodiagnosis and ultrasonography of both median nerves were performed to assess CTS in WCB players. Ultrasonographic median nerves evaluation was conducted after wheelchair propulsion for 20 minutes.
Average body mass index (BMI) and period of wheelchair use of CTS subjects were greater than those of normal subjects. Electrodiagnosis revealed CTS in 14 of 30 hands (47%). Cross-sectional area (CSA) of median nerve was greater in CTS subjects than in normal subjects at 0.5 cm and 1 cm proximal to distal wrist crease (DWC), DWC, 1 cm, 2 cm, 3 cm, and 3.5 cm distal to DWC. After exercising, median nerve CSAs at 0.5 cm and 1 cm proximal to DWC, DWC, and 3 cm and 3.5 cm distal to DWC were greater than baseline CSAs in CTS subjects; and median nerve CSAs at 1 cm proximal to DWC and DWC were greater than baseline CSAs in normal subjects. The changes in median nerve CSA after exercise in CTS subjects were greater than in normal subjects at 0.5 cm proximal to DWC and 3 cm and 3.5 cm distal to DWC.
BMI and total period of wheelchair use contributed to developing CTS in WCB players. The experimental exercise might be related to the median nerve swelling around the inlet and outlet of carpal tunnel in WCB athletes with CTS.
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To identify the anatomic characteristics of the pronator quadratus (PQ) muscle and the entry zone (EZ) of the anterior interosseous nerve (AIN) to this muscle by means of cadaver dissection.
We examined the PQ muscle and AIN in 20 forearms from 10 fresh cadavers. After identifying the PQ muscle and the EZ of the AIN, we measured the distances from the midpoint (MidP) of the PQ muscle and EZ to the vertical line passing the tip of the ulnar styloid process (MidP_X and EZ_X, respectively) and to the medial border of the ulna (MidP_Y and EZ_Y, respectively). Forearm length (FL) and wrist width (WW) were also measured, and the ratios of MidP and EZ to FL and of MidP and EZ to WW were calculated.
The MidP was found to be 3.0 cm proximal to the ulnar styloid process or distal 13% of the FL and 2.0 cm lateral to the medial border of the ulna or ulnar 40% side of the WW, which was similar to the location of EZ. The results reveal a more distal site than was reported in previous studies.
We suggest that the proper site for needle insertion and motor point block of the PQ muscle is 3 cm proximal to the ulnar styloid process or distal 13% of the FL and 2 cm lateral to the medial border of the ulna or ulnar 40% side of the WW.
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To determine the midpoint (MD) of extensor hallucis longus muscle (EHL) and compare the accuracy of different needle electromyography (EMG) insertion techniques through cadaver dissection.
Thirty-eight limbs of 19 cadavers were dissected. The MD of EHL was marked at the middle of the musculotendinous junction and proximal origin of EHL. Three different needle insertion points of EHL were marked following three different textbooks: M1, 3 fingerbreadths above bimalleolar line (BML); M2, junction between the middle and lower third of tibia; M3, 15 cm proximal to the lower border of both malleoli. The distance from BML to MD (BML_MD), and the difference between 3 different points (M1–3) and MD were measured (designated D1, D2, and D3, respectively). The lower leg length (LL) was measured from BML to top of medial condyle of tibia.
The median value of LL was 34.5 cm and BML_MD was 12.0 cm. The percentage of BML_MD to LL was 35.1%. D1, D2, and D3 were 7.0, 0.9, and 3.0 cm, respectively. D2 was the shortest, meaning needle placement following technique by Lee and DeLisa was closest to the actual midpoint of EHL.
The MD of EHL is approximately 12 cm above BML, and about distal 35% of lower leg length. Technique that recommends placing the needle at distal two-thirds of the lower leg (M2) is the most accurate method since the point was closest to muscle belly of EHL.
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To find the optimal needle insertion site for needle electromyography of the pronator teres (PT) muscle among commonly used sites.
Fifty forearms of 25 healthy subjects were evaluated. Four expected needle insertion points were designated as follows. Point 0 was positioned at the midpoint between the medial epicondyle and medial border of biceps tendon in the elbow crease. Points 1, 2, and 3 were located 2 cm, 3.5 cm and 5 cm distal to point 0, respectively. We assumed that the thickness of PT and the distances between a vertical line from each point to the medial margin of the PT were significant parameters for finding the optimal site. Thus, we measured these parameters through ultrasonographic examination.
In men, the PT was thickest at point 2, and in women, at point 1. The distance between the expected needle insertion line and medial margin of PT was longest at point 1 in both men and women, and was statistically significant compared to points 2 and 3. Both men and women had neurovascular bundles located lateral to the expected needle insertion line.
The most appropriate and safe needle electromyographic insertional site for the PT is 2-3.5 cm distal to the mid-point between the biceps tendon and medial epicondyle in the elbow crease and the needle should be inserted upward and medial.
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To investigate the anatomic relationship between the superficial radial nerve (SRN) and the cephalic vein (CV) through ultrasonography due to the possibility of SRN injury during cephalic venipuncture.
Both forearms of 51 healthy volunteers with no history of trauma or surgery were examined in proximal to distal direction using ultrasonography. We measured the distance between the radial styloid process (RSP) and the point where the SRN begins contact with the CV, and measured the distance between the RSP and the point where the SRN is separated from the CV. The point where the SRN penetrates the brachioradialis fascia was also evaluated.
The SRN came in contact with the CV at a mean of 9.35±1.05 cm from the RSP and separated from the CV at a mean of 6.29±1.17 cm from the RSP. The SRN pierced the brachioradialis fascia at a mean of 10.31±0.89 cm from the RSP and horizontally 1.35±0.36 cm medial to the radius margin. All parameters had no significant differences in gender or direction.
The SRN had close approximation to the CV in the distal second quarter of the forearm. We recommend for cephalic venipuncture to be avoided in this area, and, if needed, it should be carried out with care not to cause injury to the SRN.
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To identify the optimal distal stimulation point for conventional deep peroneal motor nerve (DPN) conduction studies by a cadaveric dissection study.
DPN was examined in 30 ankles from 20 cadavers. The distance from the DPN to the tibialis anterior (TA) tendon was estimated at a point 8 cm proximal to the extensor digitorum brevis (EDB) muscle. Relationships between the DPN and tendons including TA, extensor hallucis longus (EHL), and extensor digitorum longus (EDL) tendons were established.
The median distance from the DPN to the TA tendon in all 30 cadaver ankles was 10 mm (range, 1-21 mm) at a point 8 cm proximal to the EDB muscle. The DPN was situated between EHL and EDL tendons in 18 cases (60%), between TA and EHL tendons in nine cases (30%), and lateral to the EDL tendon in three cases (10%).
The optimal distal stimulation point for the DPN conduction study was approximately 1 cm lateral to the TA tendon at the level of 8 cm proximal to the active electrode. The distal stimulation site for the DPN should be reconsidered in cases with a weaker distal response but without an accessory peroneal nerve.
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To investigate the correlation of the ultrasonographic wrist-to-forearm median nerve area ratio (WFR) and cross sectional area of median nerve at the wrist (CSA-W) to the electrophysiologic severity in patients with carpal tunnel syndrome (CTS).
One hundred and ten wrists electrophysiologically graded as mild, moderate, and severe CTS and 38 healthy controls underwent ultrasonography of median nerve at the distal wrist crease and mid-forearm. WFR and CSA-W were analyzed according to the severity of CTS.
WFR was 1.12±0.14, 1.91±0.33, 2.27±0.47 and 3.02±0.97 and the CSAs-W was 7.23±1.67 mm2, 13.51±3.72 mm2, 14.67±2.93 mm2, and 18.74±6.01 mm2 in controls, mild (n=28), moderate (n=46), and severe (n=36) CTS, respectively. CSA-W displayed significant differences between the control and the mild CTS, moderate CTS and severe CTS groups. However, there was no significant difference between mild CTS and moderate CTS groups. WFR revealed significant difference between all groups. The sensitivity and specificity of the WFR in grading the severity of CTS were higher than those of the CSA-W.
Ultrasonography is a useful complementary tool for the evaluation of CTS. Both WFR and CSA-W are highly correlated with severity grade of CTS. However, WFR is superior to CSA-W for diagnosis and grading of the severity of CTS.
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