Relationship between EMG-detected and ultrasound-detected fasciculations in amyotrophic lateral sclerosis: A prospective cohort study

ObjectivesFasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).MethodsThirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.ResultsThe mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch’s t-test).ConclusionSmall FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.SignificanceClinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS.     

三种固定剂对氯化金染色大鼠运动终板效果的比较

目的 对比分析25%甲酸、25%乙酸和4%甲醛3种固定剂对氯化金染色运动终板的效果。方法 选用30只SD大鼠,体重180～220 g,雌雄不拘。进行10次实验,每次实验随机选取3只,取右侧肱二头肌,分别置于25%甲酸、25%乙酸和4%甲醛溶液中固定后,行氯化金镀金法,光学显微镜下观察运动终板的形态结构和背景颜色。结果 3种固定剂固定的运动终板边缘整齐,中央颜色浅于周围,部分运动终板中央呈空泡状。甲酸固定的肌纤维排列有序,横纹清晰,呈紫红色;乙酸固定的肌纤维排列有序,无清晰的横纹,呈紫蓝色,但染色较浅,与运动终板形成的反差较小;甲醛固定的肌纤维排列杂乱,无横纹,呈紫红色、粉红色、紫黑色和蓝色等多种颜色。结论 甲酸固定的运动终板氯化金染色效果优于乙酸和甲醛,甲酸固定的肌组织需要的还原时间少于乙酸和甲醛。因此,进行运动终板染色选择固定剂时,25%甲酸在3种固定试剂中可作为最佳选择。     

A SLAP lesion associated with calcific tendinitis of the long head of the biceps brachii at its origin

Calcific tendinitis is a common condition with characteristic clinical and radiological findings. Although we do not know which condition initiated the pathologic cascade, we present a rare case of calcific tendinitis of the long head of the biceps brachii at its origin, associated with a SLAP lesion. The calcium deposit was removed and the SLAP lesion was repaired with a suture anchor arthroscopically.     

Supernumerary humeral heads of the biceps brachii muscle revisited

Supernumerary humeral heads of the biceps brachii muscle were found in 27 (15.4%) of 175 cadavers. They were bilateral in five cadavers and unilateral in 22 (8 left, 14 right), giving a total of 32 examples in 350 arms (9.1%). Depending on their origin and location, the supernumerary heads were classified as superior, infero-medial, and infero-lateral humeral heads. Previous studies were reviewed using this classification. The infero-medial humeral head was observed in 31 of 350 (9%) arms and was therefore the most common variation. The superior humeral head was observed in five (1.5%). The infero-lateral humeral head was the least common variation, observed only in one (0.3%) of 350 arms. A biceps brachii with three heads was observed in 27 of 350 (7.7%) arms and with four heads in five (1.4%) arms.     

Quadriceps-hamstring EMG activity during functional, closed kinetic chain exercise to fatigue

It has been hypothesized that the ability of the neuromuscular system to co-contract muscles for joint stabilization may be impaired during the development of fatigue. The purpose of this study was to examine muscle activation of the quadriceps and hamstring muscles during a prolonged closed kinetic chain exercise, the forward lunge. Eight males and two females [mean (SD) age 26.0 (2.3) years, height 177.2 (13.6) cm, body mass 82.8 (17.1) kg] with no prior knee pathology volunteered for this study. Subjects performed repeated forward lunges onto their dominant leg at the cadence of one full lunge cycle every 2 s, until the point of volitional failure. Digital switches were positioned to record foot-strike and knee-strike of the lunge leg at the midpoint of the lunge, as well as heel-strike upon return to stance. During the lunge performance, surface electromyographic (EMG) signals of the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) muscles of the supporting leg were measured. Heart rate was also monitored every 30 s during the performance. All EMG data were full-wave rectified, partitioned into up and down phases, and integrated over the entire exercise period. The results demonstrated a significant increase in activation of the VL, VM, and BF during performance of the forward lunge to volitional failure (P < 0.05). No significant increase was shown for the ST. Heart rate increased significantly over the course of the lunge. These findings suggest that activation of the VL, VM, and BF muscles occurs as a unit during performance of the forward lunge during both concentric and eccentric lunge phases. Accepted: 25 October 1999     

Functionally complex muscles of the cat hindlimb

The biceps femoris (BF) muscle is divided into three neuromuscular compartments defined by the innervation patterns of the main nerve branches (English and Weeks 1987). The goals of this study were i) to determine how different regions of the biceps femoris muscle are activated in the intact cat during a broad range of limb movements evoked by perturbations of stance posture, and ii) to determine the relationship between the anatomical compartments of biceps femoris and the functional units as defined in this task. Cats were trained to stand on a moveable platform with each paw on a triaxial force plate. The animal's stance was perturbed by linear translation of the platform in each of sixteen different directions in the horizontal plane. EMG activity was recorded from eight sites across the width of the left biceps femoris muscle. During quiet stance only the anterior compartment was tonically active, presumably contributing to hip extensor torque in the maintenance of stance. During platform translation, evoked EMG activity was recorded from each electrode pair for a wide range of directions of perturbation; as direction changed progressively, the amplitude of evoked activity from any electrode pair increased to a maximum and then decreased. When the EMG amplitude was plotted in polar coordinates as a function of translation direction, the region of response formed a petal shaped area in the horizontal plane, termed the EMG tuning curve. The compartments of the BF muscle were not activated homogeneously. The tuning curve of the anterior BF compartment was similar to that of other hip extensors, and coincided with the region of postero-lateral force production by the hindlimb against the support. The tuning curve of the middle BF compartment was shifted in a counterclockwise direction from that of the anterior compartment, but overlapped extensively with it; the middle BF tuning curve was similar to that of anterior gracilis. The tuning curve of the posterior biceps compartment was rotated further counterclockwise and overlapped very little with that of the middle BF compartment. The posterior BF was activated in a pattern similar to that of other knee flexors. The functional units of BF activation were not identical with the neuromuscular compartments defined by the main nerve branches. As direction of the perturbation changed, the region of BF that was activated moved progressively across the muscle. This progression of the active region was continuous across BFa and BFm, whereas there was a jump, or discontinuity at the border between BFm and BFp.(ABSTRACT TRUNCATED AT 400 WORDS)