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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 demonstrate the bifurcation pattern of the tibial nerve and its branches.
Eleven legs of seven fresh cadavers were dissected. The reference line for the bifurcation point of tibial nerve branches was an imaginary horizontal line passing the tip of the medial malleolus. The distances between the reference line and the bifurcation points were measured. The bifurcation branching patterns were categorized as type I, the pattern in which the medial calcaneal nerve (MCN) branched most proximally; type II, the pattern in which the three branches occurred at the same point; and type III, in which MCN branched most distally.
There were seven cases (64%) of type I, three cases (27%) of type III, and one case (9%) of type II. The median MCN branching point was 0.2 cm (range, -1 to 3 cm). The median bifurcation points of the lateral plantar nerves and inferior calcaneal nerves was -0.6 cm (range, -1.5 to 1 cm) and -2.5 cm (range, -3.5 to -1 cm), respectively.
MCN originated from the tibial nerve in most cases, and plantar nerves were bifurcated below the medial malleolus. In all cases, inferior calcaneal nerves originated from the lateral plantar nerve. These anatomical findings could be useful for performing procedures, such as nerve block or electrophysiologic studies.
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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 demonstrate the prevalence and characteristics of subclinical ulnar neuropathy at the elbow in diabetic patients.
One hundred and five patients with diabetes mellitus were recruited for the study of ulnar nerve conduction analysis. Clinical and demographic characteristics were assessed. Electrodiagnosis of ulnar neuropathy at the elbow was based on the criteria of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM1 and AANEM2). The inching test of the ulnar motor nerve was additionally performed to localize the lesion.
The duration of diabetes, the existence of diabetic polyneuropathy (DPN) symptoms, the duration of symptoms, and HbA1C showed significantly larger values in the DPN group (p<0.05). Ulnar neuropathy at the elbow was more common in the DPN group. There was a statistically significant difference in the number of cases that met the three diagnostic criteria between the no DPN group and the DPN group. The most common location for ulnar mononeuropathy at the elbow was the retrocondylar groove.
Ulnar neuropathy at the elbow is more common in patients with DPN. If the conduction velocities of both the elbow and forearm segments are decreased to less than 50 m/s, it may be useful to apply the AANEM2 criteria and inching test to diagnose ulnar neuropathy.
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To evaluate each digital branch of the median sensory nerve and motor nerves to abductor pollicis brevis (APB) and 2nd lumbrical (2L) according to the severity of carpal tunnel syndrome (CTS).
A prospective study was performed in 67 hands of 41 patients with CTS consisting of mild, 23; moderate, 27; and severe cases, 17. Compound muscle action potentials (CMAPs) were obtained from APB and 2L, and median sensory nerve action potentials (SNAPs) were recorded from the thumb to the 4th digit. Parameters analyzed were latency of the median CMAP, latency difference of 2L and first palmar interosseous (PI), as well as latency and baseline to peak amplitude of the median SNAPs.
The onset and peak latencies of the median SNAPs revealed significant differences only in the 2nd digit, according to the severity of CTS, and abnormal rates of the latencies were significantly lower in the 2nd digit to a mild degree. The amplitude of SNAP and sensory nerve conduction velocities were more preserved in the 2nd digit in mild CTS and more affected in the 4th digit in severe CTS. CMAPs were not evoked with APB recording in 4 patients with severe CTS, but obtained in all patients with 2L recording. 2L-PI showed statistical significance according to the severity of CTS.
The branch to the 4th digit was mostly involved and the branch to the 2nd digit and 2L were less affected in the progress of CTS. The second digit recorded SNAPs and 2L recorded CMAPs would be valuable in the evaluation of severe CTS.
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Blind intramuscular injection might cause severe neurovascular injury if it would be performed with insufficient knowledge of anatomy around the injection area. We report a case of pseudo-anterior interosseous syndrome caused by multiple intramuscular steroid injections around the antecubital area. The patient had weakness of the 1st to 3rd digits flexion with typical OK sign. Muscle atrophy was noted on the proximal medial forearm, and sensation was intact. The electrophysiologic studies showed anterior interosseous nerve compromise, accompanying with injury of the other muscles innervated by the median nerve proximal to anterior interosseous nerve. Magnetic resonance imaging of the left proximal forearm revealed abnormally increased signal intensity of the pronator teres, flexor carpi radialis, proximal portion of flexor digitorum superficialis, and flexor digitorum profundus innervated by the median nerve on the T2-weighted images. This case shows the importance of knowledge about anatomic structures in considering intramuscular injection.
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Typical venous malformations are easily diagnosed by skin color changes, focal edema or pain. Venous malformation in the skeletal muscles, however, has the potential to be missed because their involved sites are invisible and the disease is rare. In addition, the symptoms of intramuscular venous malformation overlaps with myofascial pain syndrome or muscle strain. Most venous malformation cases have reported a focal lesion involved in one or adjacent muscles. In contrast, we have experienced a case of intramuscular venous malformation that involved a large number of muscles in a lower extremity extensively.
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This study reports a rare case of ulnar neuropathy around the arm with Martin-Gruber anastomosis of a moderate conduction block in the forearm segment and a severe conduction block in the arm segment. Inching tests and ultrasonography showed a lesion between 12 and 14 cm from the medial epicondyle. It is concluded that axilla stimulation may provide diagnostic clues, and inching tests and ultrasonography may be helpful for localizing a lesion.
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Ulnar neuropathy at the wrist is rarely reported as complications of carpal tunnel release. Since it can sometimes be confused with recurrent median neuropathy at the wrist or ulnar neuropathy at the elbow, an electrodiagnostic study is useful for detecting the lesion in detail. We present a case of a 51-year-old woman with a two-week history of right ulnar palm and 5th digit tingling sensation that began 3 months after open carpal tunnel release surgery of the right hand. Electrodiagnostic tests such as segmental nerve conduction studies of the ulnar nerve at the wrist were useful for localization of the lesion, and ultrasonography helped to confirm the presence of the lesion. After conservative management, patient symptoms were progressively relieved. Combined electrodiagnostic studies and ultrasonography may be helpful for diagnosing and detecting ulnar neuropathies of the wrist following carpal tunnel release surgery.
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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 derive normative values for ulnar nerve conduction study of the active recording electrode on the first dorsal interosseous muscle (FDI) and the reference electrode on the proximal phalanx of the thumb.
Ulnar nerve motor conduction study with FDI and abductor digiti minimi muscle (ADM) recording was performed in 214 hands of 107 healthy subjects. Ulnar NCS was performed with 2 different recording electrode montages (ADM-base of 5th finger; FDI-thumb) and differences in latency and amplitude were compared. Using this technique, the initial positivity of ulnar compound muscle action potential (CMAP) was not observed in any response with FDI recording.
The maximal values for distal motor latency to the ADM and FDI muscle were 3.8 ms and 4.4 ms, respectively. The maximal difference of distal motor latency between the bilateral FDI recordings was 0.6 ms. The maximal ipsilateral latency difference between ADM and FDI was 1.4 ms.
Placement of the reference electrode on the thumb results in a CMAP without an initial positivity and the normative values obtained may be useful in the diagnosis of ulnar neuropathy at the wrist.
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True neurogenic thoracic outlet syndrome (TOS) is an uncommon disease and is difficult to diagnose at the early stage and then completely cure. We experienced a case of true neurogenic TOS with typical clinical symptoms and electrophysiologic findings as a result of repetitive habitual sleep posture. A 31-year-old woman who had complained of progressive tingling sensation on the 4th and 5th fingers with shoulder pain was diagnosed of brachial plexopathy at the lower trunk level by electrodiagnostic studies. There was no other cause of brachial plexopathy except her habit of hyperabduction of shoulder during sleep. This case demonstrated that the habitual abnormal posture can be the only major cause of neurogenic TOS. It is of importance to consider TOS with the habitual cause because simple correction of the posture could stabilize or even reverse disease progress.
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