Functional connectivity of the transected brachial plexus after intercostal neurotization in monkeys

Microsurgical reconstructions of brachial plexuses were performed on twelve monkeys by using ipsilateral intercostal nerves (T3-9). Reinnervation in individual nerves was evaluated monthly by observations of neuromuscular and electromyographic improvements. The electromyographic studies revealed reappearance of motor unit potentials. According to a motor scale ranging from 0 to 4, the mean muscle power 6 months after operation improved to 2.75 in the deltoid muscles, 2 in the biceps muscles, 1.22 in the triceps muscles, 1.13 in the flexor carpi radialis muscles, and 1.6 in the intrinsic muscles of the hands. Retrograde transport of horseradish peroxidase (HRP) from the neuromuscular junctions of the reconstructed musculocutaneous nerves 6 months after complete brachial plexus lesion in four animals demonstrated HRP-labeled neurons in the anterior horns, spinal ganglia and sympathetic ganglia of the thoracic spinal cords. It suggested that the regenerated afferent and efferent circuits in the thoracic cords innervating the transected brachial plexuses were able to generate the movements in the paralyzed upper limbs. However, as evidenced by the behavior patterns and the fact that retrograde-labeled neurons were all found in the thoracic cords, the novel movements observed in the reconstructed brachial plexuses were in synchrony with respiration. These results suggested that the plasticity of central neural networks is limited between two widely separated areas, such as between the midcervical and midthoracic motor cortical areas in the present studies, and therefore, the efforts to reconstruct neural networks, both centrally and peripherally, should aim at rebuilding situations as nearly to the original status as possible. J. Comp. Neurol. 380:155–163, 1997. © 1997 Wiley-Liss, Inc.     

基于表面肌电技术对卒中患者上肢运动时躯干肌用力疲劳程度的研究

目的 探讨卒中患者上肢运动过程中躯干肌用力疲劳情况。 方法 前瞻性连续纳入2019年4-9月于中山大学附属第三医院康复医学科住院的卒中患者作为卒中 组,并招募年龄、性别匹配的健康志愿者作为对照组。使用木插板分别让卒中患者的健侧和患侧上 肢、健康志愿者利手侧上肢进行前后向置物-返回运动各15次,分3组完成,每组5次,组间间隔30 s。 受试者在运动前后根据改良版Borg自觉用力程度量表对其自身疲劳程度进行评价,对比受试者运动 前后的量表评分结果。利用表面肌电技术采集进行前后向置物-返回运动时躯干肌（运动侧斜方肌、 双侧腹直肌、双侧腹外斜肌、双侧胸段及腰段竖脊肌）的肌电频域指标[平均功率频率（mean power frequency,MPF）]平均值,分别比较卒中患者健侧、患侧运动时与健康志愿者利手侧肌肉MPF的差异。 结果 卒中组患侧和健侧上肢运动后改良版Borg自觉用力程度量表评分均较运动前升高（均P ＜0.001）,而对照组运动前后差异无统计学意义。使用表面肌电图技术分析发现,在前后向置物-返 回运动过程中,相比对照组,卒中组患者不论用患侧还是健侧上肢运动,其健侧腹直肌、患侧腹直 肌、健侧腹外斜肌、患侧胸段竖脊肌的MPF均较低,以上差异均具有统计学意义;其余肌肉两组差异 无统计学意义。 结论 卒中患者双上肢活动时躯干肌群容易出现疲劳。在进行上肢前后向置物-返回动作过程中, 双侧腹直肌、健侧腹外斜肌和患侧胸段竖脊肌的疲劳程度更加明显。     

Acoustic and electrical activities during voluntary isometric contraction of biceps brachii muscles in patients with spastic cerebral palsy

This study was designed to compare electromyogram (EMG) and acoustic myogram (AMG) recordings of biceps brachii muscles in patients with spastic cerebral palsy (CP). The maximal voluntary contraction (MVC) in the CP group was approximately one half of that of the normal group even after being normalized by the muscle cross-sectional area (CSA) (18.6 ± 5.9 kNm/m² in CP, 37.3 ± 2.9 kNm/m² in normal). Both CP and normal groups demonstrated a progressive increase in the root mean squared values per unit muscle CSA in the EMG (RMS_EMG/CSA) as well as in the AMG (RMS_AMG/CSA) with increasing force up to 50% MVC. The increasing magnitude of the RMS_EMG/CSA with force was not significantly different between two subject groups. However, all the levels of force resulted in significantly smaller RMS_AMG/CSA in the CP group compared to the normal group. The ratios of RMS_AMG to RMS_EMG in the CP group (0.75 ± 0.03 m/s²/mV) were significantly smaller than those in the normal group (1.37 ± 0.07 m/s²/mV) at force levels above 30% MVC. These results suggest that motor disabilities in CP patients are caused not only by primary neural impairment but also by secondary deterioration in muscular contractile properties, probably resulting from muscle fiber atrophy. This appears to be more selective in fast twitch fibers. © 1996 John Wiley & Sons, Inc.     

The translabyrinthine approach in residency training.“Step by step”surgical anatomy from the dissection laboratory to the operative room

Surgical anatomy training in a dedicated research laboratory and attendance to focused“hands-on”dissection courses are of high educational importance in order to acquire and maintain surgical expertise in skull base surgery,both for young and more experienced surgeons.Nevertheless,transitioning surgical skills and anatomic knowledge from the laboratory to the operative room it is not free of challenges,especially during skull base approaches where the three-dimensional surgical orientation can be quite complex.We present a“step-by-step”and“side-by-side”surgical anatomy report on a translabyrinthine approach that was practiced in the laboratory then performed in the operative room by the surgical team,and we compare surgical anatomy exposures while discussing intraoperative techniques,nuances and challenges,both in the laboratory and the operative room.     

Effect of local administration of eicosapentaenoic acid on the jaw-opening reflex in rats

Although eicosapentaenoic acid (EPA) application in vitro inhibits voltage-gated Na⁺ (Nav) channels in excitable tissues, the acute local effect of EPA on the jaw-opening reflex in vivo remains unknown. The aim of the present study was to determine whether local administration of EPA to adult male Wistar rats could attenuate the excitability of the jaw-opening reflex in vivo, including nociception. The jaw-opening reflex evoked by electrical stimulation of the tongue was recorded by a digastric muscle electromyogram (dEMG) in pentobarbital-anesthetized rats. The amplitude of the dEMG response was significantly increased in proportion to the electrical stimulation intensity (1×–5× threshold). At 3×, local administration of EPA dose-dependently inhibited the dEMG response, lasting 60 min, with maximum inhibition observed within approximately 10 min. The mean magnitude of dEMG signal inhibition by EPA was almost equal to that observed with a local anesthetic, 1% lidocaine, and with a half dose of lidocaine plus a half dose of EPA. These findings suggest that EPA attenuates the jaw-opening reflex, possibly by blocking Nav channels of primary nerve terminals, and strongly support the idea that EPA is a potential therapeutic agent and complementary alternative medicine for the prevention of acute trigeminal nociception.     

Thyrotoxic periodic paralysis associated with lactic metabolic acidosis: Case report of an African man and review of literature

BackgroundThyrotoxic periodic paralysis (TPP) is a rare and most often acquired subtype of hypokalemic periodic paralysis. The association of varying degrees of muscle weakness, hyperthyroidism and hypokalemia characterizes it. The treatment requires potassium supplementation, control of hyperthyroidism and prevention measures. It is a frequent disease in Asian men, but much rare in Caucasian or African populations. This is the first report of TPP associated with lactic metabolic acidosis in an African man.Case presentationA 23 year-old African man, native from Morocco, with recurrent episodes of tetraparesis for eleven months, and abdominal pain, was referred for evaluation. Biochemical investigations showed severe hypokalemia associated with hyperthyroidism and lactic metabolic acidosis. His EKG showed signs of hypokalemia such as sinus tachycardia and U waves. After potassium supplementation, neurological recuperation was quick and complete. Thyroid ultrasound identified a hypoechogenic and hypervascularized goiter, associated with high levels of thyroid antibodies, in favor of Grave's disease. With antithyroid drugs and life-style changes, the patient did not have any other attack.Review of literatureIn addition to the case report, this article presents an extended review of literature, from the first large study reporting the diagnosis and incidence of TPP in 1957 to nowadays. Are reported here the latest information concerning epidemiology, clinical manifestations, complementary examinations, management and genetic finding. The lactic acidosis observed initially is exceptional, never described in TPP. TPP is a diagnostic and therapeutic emergency, requiring careful potassium supplementation, in order to avoid the risk of the onset of rebound hyperkalemia, to be maintained until the etiological treatment is effective. Paraclinical assessment with emergency EKG and electromyogram are essential to assess the impact.DiscussionIt is essential in the face of any hypokalaemic periodic paralysis, including in non-Asian subjects, to search hyperthyroidism.ConclusionsThis report demonstrates the importance of thyroid testing in case of acute muscle weakness, even in non-Asian patients in order to diagnose TPP. This is a rare but possible etiology, to be distinguished from the familial form of hypokalemic periodic paralysis. It also questions on the impact of TPP on energetic metabolism, in particular on lactic metabolism.