Extensor Digitorum Brevis Research Articles

Analysis of surface EMG activation in hand percussion playing depending on the grasping type and the tempo.

Although instrument playing-based training has been repeatedly reported to improve functional hand movements including grasping, the attempts to present quantitative information on physiological mechanism of grasping have been relatively insufficient to determine the type and the intensity of the exercises involved. This study aimed to examine the muscle activation during hand percussion playing depending on the grasping type and the playing tempo. A total of twelve healthy older adults with a mean age of 71.5 years participated in this study. Surface electrodes were placed on three grasping-related muscles: Flexor digitorum superficialis, extensor digitorum, and flexor pollicis brevis. Participants were instructed to play with the egg shaker, paddle drum mallet and clave involving different types of grasp at three different tempi (i.e., 80, 100, and 120 bpm) and sEMG data were collected during each playing. Significantly greater muscle activation was generated with the small sphere type of egg shaker, compared to the handle type of paddle drum mallet and the small cylinder type of clave. Playing at faster tempo also elicited significantly greater muscle activation than at slower tempo. With regard to the rise time of muscle activation, while tempo significantly affected the rise time, the time to peak muscle did not significantly change depending on the grasping type. This study confirmed that grasping pattern and the tempo of movement significantly influence the muscular activation of grasping involved in instrument playing. Based on these results, clinical implication for instrument selection and structured instrument playing would be suggested.

Evaluation of extensor digitorum brevis thickness in healthy subjects: A comparative analysis of nerve conduction studies and ultrasound scans

Objectives(1) To evaluate the relationship between the thickness and compound muscle action potential (CMAP) of the extensor digitorum brevis (EDB) muscle; (2) to obtain reference values for distal lower extremity muscle thickness as a possible measure of peripheral neuropathy; and (3) to evaluate various factors associated with unexplained EDB atrophy. MethodsWe measured the thickness of EDB, abductor hallucis brevis (AHB) and tibialis anterior (TA) muscles in 80 healthy volunteers with ultrasound and assessed EDB CMAP with fibular nerve stimulation. Two foot muscle-associated lifestyle factors were assessed and sociodemographic information was collected. ResultsA significant correlation was observed between the amplitude of the fibular nerve CMAP and EDB thickness. The thickness of each of the three muscles was greater in men compared to women. EDB thickness decreased significantly with age although the thicknesses of the AHB and TA muscles were not correlated with age. ConclusionsEDB thickness was closely associated with fibular nerve CMAP but with less variation and differed among groups by age and sex; it was not associated with lifestyle factors. SignificanceThe ability to obtain this measure painlessly with ultrasound and its low variation recommend it as a potentially useful complementary measure of distal neuromuscular function.

An alternative nerve conduction study method to evaluate early diabetic neuropathy: Ratio of different diameter nerve fibers in peroneal nerve

Different nerve fibers may have disparate conduction parameters even though they are in the same peripheral nerve. Hyperglycemia can have differential effects on nerve fibers, depending on diameter. In diabetes, conventional nerve conduction studies have allowed us to classify a peripheral nerve as normal or not. But, there may be differential involvement in disparate nerve fibers of the same peripheral nerve. This study evaluated the effects of hyperglycemia on nerve fibers of peroneal nerve by diameter. Thirty-five diabetic patients with normal nerve conduction studies and thirty-two healthy controls were included to the study. The peroneal nerve was stimulated from two points (upper and below the fibula head) and recorded from the tibialis anterior (TA) and extensor digitorum brevis (EDB) muscles. Then the ratios of conduction velocity parameters recorded in these sides were compared between the diabetic and control groups. The conduction velocity recorded from EDB seemed to be faster in both groups. But there were no significant differences among the ratios between the groups. Our study has demonstrated the conduction parameters of two nerve fibers with different diameters in the peroneal nerve. The ratios of conduction parameters were similar in both groups, suggesting that fibers in the peroneal nerve are similarly affected by hyperglycemia.

Calcaneal Osseous Avulsion of the Extensor Digitorum Brevis With Radiographic and Magnetic Resonance Imaging Correlation

Calcaneal Osseous Avulsion of the Extensor Digitorum Brevis With Radiographic and Magnetic Resonance Imaging Correlation

Nerve conduction studies after decompression in painful diabetic polyneuropathy.

To investigate the influence of nerve decompression at potential entrapment sites in the lower extremity in painful diabetic polyneuropathy on nerve conduction study variables. Forty-two patients with painful diabetic polyneuropathy were included in this prospective randomized controlled trial. Preoperative nerve conduction studies were performed bilaterally. Each patient underwent unilateral surgical decompression of the tibial nerve and common, superficial, and deep peroneal nerves. The contralateral side was used as a control: within-patient comparison. One year postoperatively, the nerve conduction studies were repeated. Univariate paired sample T-tests and a multivariate analysis of variance were performed to compare data. In univariate analysis of the peroneal nerve, the distal compound muscle action potential amplitude measured at the extensor digitorum brevis muscle of the intervention legs decreased significantly, as did the area drop measured at the extensor digitorum brevis muscle of the control legs. The distal motor latency measured at the extensor digitorum brevis muscle of the intervention legs increased significantly, as did the distal compound muscle action potential amplitude measured at the anterior tibial muscle of the control legs. For the tibial nerve, the distal compound muscle action potential duration decreased significantly in the control legs. The multivariate analysis showed no significance overall. Decompression of nerves of the lower extremity in patients with painful diabetic polyneuropathy has no beneficial effect on nerve conduction study variables 12 months after surgery.

Temporal profile of the effects of regional anesthesia on the cutaneous reflexes of foot muscles

We analyzed the effects of an anesthetic sciatic nerve block on the cutaneomuscular reflex (cMR) and the cutaneous silent period (cSP) of foot muscles, in order to investigate further the type of fibers involved in their generation. In 14 neurologically normal patients with indication for surgical treatment of hallux valgus, we recorded from the extensor digitorum brevis muscle the reflex responses elicited by high-intensity electrical stimulation of the big toe at various time periods, ranging from 0 to 20 min, after ultrasound-guided sciatic nerve popliteal anesthetic block. The first effect was a delay in cSP onset latency, with no changes in end latency. The cMR remained unaltered up to when subjects were no longer able to maintain the contraction. The effects of local anesthetics on peripheral nerves allow for recognition of the different types of fibers contributing to the cMR and the cSP in muscles of the lower limb.

Fibular motor nerve conduction studies: Investigating the mechanism for compound muscle action potential amplitude drop with proximal stimulation.

The compound muscle action potential (CMAP) amplitude of extensor digitorum brevis can show a drop with proximal stimulation in normal fibular nerves. We assessed the contribution of the far-field potential recorded by the reference electrode (R-CMAP) to the fibular CMAP. Negative R-CMAP amplitude, peak-to-peak amplitude, and negative area were measured and correlated with the amplitude decrease. Fibular motor nerves from 14 healthy participants were studied. The mean CMAP amplitude drop with proximal stimulation was 14.0 ± 9.3%, including a >30% reduction in 1 study. All measured R-CMAP parameters correlated with the degree of amplitude drop. A greater R-CMAP contribution to the fibular CMAP leads to greater phase cancellation and temporal dispersion. The resulting amplitude drop seen in the proximal CMAP can be large enough to be classified incorrectly as "probable conduction block" by several different diagnostic criteria.

Coordination of intrinsic and extrinsic foot muscles during walking.

The human foot undergoes complex deformations during walking due to passive tissues and active muscles. However, based on prior recordings it is unclear if muscles that contribute to flexion/extension of the metatarsophalangeal (MTP) joints are activated synchronously to modulate joint impedance, or sequentially to perform distinct biomechanical functions. We investigated the coordination of MTP flexors and extensors with respect to each other, and to other ankle-foot muscles. We analyzed surface electromyographic (EMG) recordings of intrinsic and extrinsic foot muscles for healthy individuals during level treadmill walking, and also during sideways and tiptoe gaits. We computed stride-averaged EMG envelopes and used the timing of peak muscle activity to assess synchronous vs. sequential coordination. We found that peak MTP flexor activity occurred significantly before peak MTP extensor activity during walking (P < 0.001). The period around stance-to-swing transition could be roughly characterized by sequential peak muscle activity from the ankle plantarflexors, MTP flexors, MTP extensors, and then ankle dorsiflexors. We found that foot muscles that activated synchronously during forward walking tended to dissociate during other locomotor tasks. For instance, extensor hallucis brevis and extensor digitorum brevis muscle activation peaks decoupled during sideways gait. The sequential peak activity of MTP flexors followed by MTP extensors suggests that their biomechanical contributions may be largely separable from each other and from other extrinsic foot muscles during walking. Meanwhile, the task-specific coordination of the foot muscles during other modes of locomotion indicates a high-level of specificity in their function and control.

Accurate segmental motor innervation of human lower-extremity skeletal muscles.

There is limited knowledge about accurate segmental motor innervation of the human lower extremity skeletal muscles. The aim of the present study was to explore the truth of segmental motor innervation of the lower extremity. Included in this study were 20 patients with unilateral fracture of the sacrum and sacral nerve injury, who underwent internal fixation and decompression of the sacral nerve in our hospital between June 2009 and January 2014. L4-S4 nerve roots of the uninjured side were stimulated during operation. Motor innervation was determined by stimulating the spinal nerves with supramaximal intensity. We found the gluteus medius and the gluteus maximus were both mainly innervated by L5 and S1. In addition, the nerve fibres that innervated the extensor digitorum brevis, the abductor hallucis and the flexor digitorum brevis were mainly from S2 to S3. Our study provides the electrophysiological mapping of the segmental anatomy of the human lower extremity muscles, which should be clinically useful in helping the diagnosis and treatment of nerve injury and neuropathies.

Prevalence of accessory deep peroneal nerve in referred patients to an electrodiagnostic medicine clinic

BackgroundAccessory Deep Peroneal Nerve (ADPN) is an anatomic variation that can potentially cause disturbance in electrodiagnostic studies. This anomaly could be detected by nerve conduction studies. There are no recent updates about prevalence of this anatomic variation. Electrodiagnostic medicine clinic is the best environment for detecting presence and prevalence of this nerve, so present study enrolled.Materials & MethodsIn this cross sectional descriptive study that take place from March 2009 to July 2010, 230 cases comprising 460 legs referred for electrodiagnostic studies of upper limbs problems participated in the study. Compound muscle action potential (CMAP) and Nerve conduction Velocity (NCV) of Deep Peroneal Nerve (DPN) were measured by using EMG machine by stimulating DPN at knee, ankle and lateral malleolous areas accordingly, with recording from extensor digitorum brevis muscle. Results were analyzed and conclusion made.ResultsThe study population included 120 females (52%) and 110 (47%) males with mean age of 42.1 ± 13.5 years. ADPN was detected in 28 patients (12%). Among them,10(17.9%) had bilateral ADPN and in remained 18 cases (82.1%) APN was unilateral. In 8 patients there was no recorded CMAP from EDB by proximal and distal stimulation implying EDB agenesis. Gender distribution was similar which means half of the cases (14 patients) belonged to each gender.ConclusionThe prevalence of ADPN in this study was 12.2%, (17.9% bilateral and 82.1% unilateral).

Motor unit number estimations are smaller in children with type 1 diabetes mellitus: A case–cohort study

We studied the potential for motor unit number estimation (MUNE) to detect subclinical changes in motor unit numbers in children with type 1 diabetes mellitus (DM). Blinded observers performed clinical assessment, electrophysiology, and multipoint MUNE of the extensor digitorum brevis muscle in children with DM for ≥ 5 years and age-matched healthy controls. For 51 DM subjects, the disease duration was 9.1 ± 2.6 years. Subjects with DM and healthy controls (n=21) had similar demographics. There were no clinical symptoms or signs of peripheral neuropathy in any subject, nor differences in standard electrophysiology between cohorts. Estimated motor unit numbers were decreased significantly in children with DM (224 ± 87 vs. 274 ± 101, P=0.036). Despite the absence of clinical or standard electrophysiological differences from normal control subjects, MUNE can detect a small significant difference in children with DM, suggesting that motor unit loss begins early and subclinically in the disease.

Revisiting nonvascularized partial muscle grafts: a novel use for prosthetic control.

Sir: Although the popularity of fat grafting has skyrocketed over the past decade, nonvascularized partial skeletal muscle grafts have long been forgotten in light of their diminishing clinical applications. Historically, surgeons have used partial muscle grafts for palatopharyngeal reconstruction1 and facial reanimation,2 using the split extensor digitorum brevis muscle for eye closure and the palmaris longus for oral competence. To generate force, each muscle would rely on muscle-to-muscle neurotization, which is an inefficient way to reestablish innervation and force-generating capacity. Despite several reported successes, nonvascularized partial muscle grafts lost their popularity because they lacked the necessary force to optimally reanimate the face. Today, nonvascularized partial muscle grafts are used only as soft-tissue fillers or for obliterating the nasofrontal ducts during frontal sinus fracture repair.3 In such cases, the grafts are expected to die and be replaced by scar tissue, filling defects rather than reestablishing function. Partial muscle grafts have yet to serve a functional purpose in which muscle fiber survival is clinically necessary. Our laboratory has proposed a novel use for partial muscle grafts, namely, to harness signals from peripheral motor nerves for prosthetic control. We have developed a regenerative peripheral nerve interface model in the rat hind limb, in which a nonvascularized whole muscle graft is attached to a severed motor nerve. After undergoing a process of degeneration, regeneration, and reinnervation, this muscle-nerve construct serves as an interface for the transmission of electromyographic signals, which are detected by an epimysial electrode.4 Major benefits of this approach include decreased neuroma formation, reduced nerve trauma during recordings, and improved signal-to-noise ratio by means of neuromuscular signal amplification. To translate this regenerative peripheral nerve interface technology into humans, we have turned toward partial muscle grafts for their practical features: abundant donor tissue, decreased donor-site morbidity, ease of harvest, appropriate size selection, and overall “cookie-cutter” reproducibility. We hypothesize that partial muscle grafts can be used successfully in regenerative peripheral nerve interface construction. With our experiments underway, we report the first set of functional regenerative peripheral nerve interfaces constructed with partial muscle grafts (Fig. 1). At 4 months, maximum electromyographic peak-to-peak amplitudes ranged from 0.64 to 2.2 mV (Fig. 2).Fig. 1: In situ appearance of a regenerative peripheral nerve interface (RPNI) at 4 months. This particular regenerative peripheral nerve interface was constructed with a 130-mg graft from the lateral gastrocnemius muscle, placed along the femur, and implanted with the common peroneal nerve. Electrophysiologic testing was performed at 4 months by means of direct stimulation of the nerve and bipolar needle electromyographic recordings from the regenerative peripheral nerve interface.Fig. 2: Regenerative peripheral nerve interface signal waveforms and peak-to-peak amplitudes. After 4 months of maturation, each partial muscle graft regenerative peripheral nerve interface displayed discrete electromyographic signals, with maximum amplitudes ranging from 0.64 to 2.23 mV at threshold stimulation currents from 145 to 820 μA. Each bar represents a single regenerative peripheral nerve interface.This proof of concept underscores the potential for partial muscle grafts to be used in the clinical workplace for their signaling capabilities. There is a high demand for reliable peripheral nerve interfaces that provide multiple input control signals to take advantage of today’s most advanced hand prostheses, which are capable of many simultaneous degrees of freedom. Should partial muscle grafts prove reliable in regenerative peripheral nerve interface construction, they will support more intuitive voluntary prosthetic motion, bypass the limitations of skin-surface electromyography, and possibly serve as a platform for implantable, wireless prosthetic control. Signal detection will not be restricted by the remaining muscle volume within the residual limb or on the chest wall, which is a perceived disadvantage of targeted muscle reinnervation.5 In summary, partial muscle regenerative peripheral nerve interfaces are promising devices that may one day augment amputee functional recovery and quality of life. ACKNOWLEDGMENTS This work was supported by the Defense Advanced Research Projects Agency (N66001-11-C-4190), the Plastic Surgery Foundation, and the Frederick A. Coller Surgical Society. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. Shoshana L. Woo, M.D. Melanie G. Urbanchek, Ph.D. Paul S. Cederna, M.D. Nicholas B. Langhals, Ph.D. Section of Plastic Surgery University of Michigan Ann Arbor, Mich.

P850: Electrophysiological pattern in GLUT1 deficiency syndrome (A275T mutation)

s of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339 S269 Figure 2. The relationship between muscle strength and transcranial stimulation motor evoked potential. Conclusions: There is the positive relation between the MEP amplitude and the muscle strength. So, the fixed quantity evaluation method using the statistical technique makes TCS-MEP reliable. And TCS-MEP may enhance us to remove tumors in central nervous system and at the same time preserve motor functions. Moreover this relation between MEP and muscle strength is useful for understanding the motor control system. P850 Electrophysiological pattern in GLUT1 deficiency syndrome (A275T mutation) C. Giliberto1, V. Sofia1, R. Barone2, R. Guerrini3, M. Zappia1 1University of Catania, Department G.F. Ingrassia, Section of Neurosciences, Catania, Italy; 2University of Catania, Pediatric Neurology, Department of Pediatrics, Catania, Italy; 3University of Florence, Pediatric Neurology, Unit and Laboratories, Children’s Hospital A. Meyer, Florence, Italy Question: Glucose transporter type 1 deficiency syndrome (GLUT1DS) is characterized by impaired glucose transport across the blood-brain barrier due to SLC2A1-gene mutation. GLUT1DS infancy onset shows epileptic encephalopathy, ataxia and microcephaly although paroxysmal exerciseinduced dyskinesia and epilepsy may also be observed. Exercise and recovery-induced modifications of GLUT4 and GLUT1 expression in human muscle have been reported.We describe clinical and electromyographyc correlates of a GLUT1DS patient with adult-onset of exercise-induced dystonia. Patients and methods: A 19 year old male with mild mental retardation presented with a two-year history of episodic stiffness in his calves and feet and painless flexion of the toes followed by leg weakness triggered by exertion and starvation and alleviated by rest and eating. His father had experienced exercise-induced leg dystonia at younger age. A heterozygous missense of mutation (c.823G>A; p.A275T) of SLC2A1 gene was found in the proband and his father.The proband underwent an electromyographyc study after voluntary contraction (5 minutes) to investigate muscle membrane excitability with the evaluation of compound muscle action potential (CMAP) amplitude. Results: The test disclosed significant decrement of CMAP amplitude up to −42% (n.v.≤−20%) after 40 minutes from exercise with respect to the pre-exercise CMAP amplitude (baseline). The same test repeated after carbohydrate-rich food intake showed a significant improvement of CMAP from baseline (−26%). Conclusions: The electrophysiological study after exercise showed a reduction of CMAP amplitude in this patient with GLUT1DS (A275T mutation). Our data suggest a possible involvement of muscle membrane excitability in GLUT1DS. P851 Tracking the spatiotemporal profile of cortical and peripheral motor axon hyperexcitability in amyotrophic lateral sclerosis E. Bakola1, P. Kokotis1, R. Carr2, M. Schmelz2, M. Rentzos1, T. Zambelis1, N. Karandreas1 1University of Athens, Medical School, Department of Neurology, Athens, Greece; 2University of Heidelberg, Mannheim Medical School, Department of Anesthesiology, Mannheim, Germany Question: Recent studies using magnetic and electrical excitability tracking tools have confirmed early hyperexcitability in ALS. This study sets out to use excitability testing to examine directly the spatiotemporal profile of cortical and peripheral hyperexcitability in ALS patients simultaneously, to associate these parameters to the clinical course of the disease and to compare them with healthy controls. Methods: Nineteen patients with first-diagnosed definite ALS (group A), four patients with advanced disease (group B) and ten control healthy volunteers (group C) were included in the study. Multiple axonal excitability properties (threshold electrotonus, strength-duration time constant, recovery cycle, current-threshold relationship) and TMS investigations including measurement of resting motor threshold (RMT) and motor evoked potential (MEP) were measured. Results: In group A there were greater changes in depolarizing threshold electrotonus (TD) compared with group B (t-test p<0.03). No differences in recovery cycle, strength-duration time constant, current-threshold relationship were noted between the three groups. Regarding the cortical excitability parameters, there was a significant decrease in the slope of MEP amplitude to TMS intensity in group B with the advanced disease in comparison to controls (Mann-Whitney U test p<0.05). ANCOVA showed strong correlation between TD and slope of cortical excitability (p<0.01) after correcting for the status of the disease (groups A,B,C). Conclusions: These are preliminary results of an ongoing study trying to understand the changes in axonal and cortical excitability in first-diagnosed and advanced disease in order to provide insight into the pathophysiological basis of the disease and furthermore provide useful information for the best treatment approach in the future.

Noninvasive peroneal sensory and motor nerve conduction recordings in the rabbit distal hindlimb: feasibility, variability and neuropathy measure.

The peroneal nerve anatomy of the rabbit distal hindlimb is similar to humans, but reports of distal peroneal nerve conduction studies were not identified with a literature search. Distal sensorimotor recordings may be useful for studying rabbit models of length-dependent peripheral neuropathy. Surface electrodes were adhered to the dorsal rabbit foot overlying the extensor digitorum brevis muscle and the superficial peroneal nerve. The deep and superficial peroneal nerves were stimulated above the ankle and the common peroneal nerve was stimulated at the knee. The nerve conduction studies were repeated twice with a one-week intertest interval to determine measurement variability. Intravenous vincristine was used to produce a peripheral neuropathy. Repeat recordings measured the response to vincristine. A compound muscle action potential and a sensory nerve action potential were evoked in all rabbits. The compound muscle action potential mean amplitude was 0.29 mV (SD ± 0.12) and the fibula head to ankle mean motor conduction velocity was 46.5 m/s (SD ± 2.9). The sensory nerve action potential mean amplitude was 22.8 μV (SD ± 2.8) and the distal sensory conduction velocity was 38.8 m/s (SD ± 2.2). Sensorimotor latencies and velocities were least variable between two test sessions (coefficient of variation = 2.6–5.9%), sensory potential amplitudes were intermediate (coefficient of variation = 11.1%) and compound potential amplitudes were the most variable (coefficient of variation = 19.3%). Vincristine abolished compound muscle action potentials and reduced sensory nerve action potential amplitudes by 42–57% while having little effect on velocity. Rabbit distal hindlimb nerve conduction studies are feasible with surface recordings and stimulation. The evoked distal sensory potentials have amplitudes, configurations and recording techniques that are similar to humans and may be valuable for measuring large sensory fiber function in chronic models of peripheral neuropathies.

BoNT/D is effective in humans – but with higher dosing and shorter duration than BoNT/A

Objective: The seven serotypes A-G of botulinum neurotoxins (BoNT) are extremely potent poisons but also highly effective medicines to treat hyperactive cholinergic neurons in different diseases and symptoms such as dystonias, spasticity, pain and hyperhidrosis. However, during long-term treatment patients may become non-responsive to the approved BoNT/A and B due to antibody formation. The remaining serotypes C-G might display treatment alternatives. BoNT/D is least related with A and B thereby circumventing neutralisation in A/B non-responder. Interestingly, no human intoxication has been reported with BoNT/D. Here, we produced BoNT/D and compared its potency in mice hemidiaphragm preparations and human extensor digitorum brevis muscle (EDB) with BoNT/A and incobotulinumtoxinA.

Efecto del alprostadil en los cultivos de músculo esquelético isquémico. Estudio proteómico comparativo frente a músculo sano

IntroductionAlprostadil has vasodilator properties and inhibits platelet aggregation. Its effects on endothelial wall have been widely studied, but there is no knowledge about possible skeletal muscle effects, and differences with ischemic muscle. ObjectiveTo determine the effects of alprostadil on skeletal muscle metabolism, and to investigate possible differences with ischemic muscle. MethodsSamples were obtained in 10patients with leg above-knee amputation due to severe irreversible ischemia, of ischemic muscle (extensor digitorum brevis, groupI), and healthy muscle (quadriceps femoris, amputation edge, groupS). Muscle segments were incubated with alprostadil 5ng, or without it (baseline). Proteomic analysis of metabolic enzymes was performed: Triose-phosphate isomerase (TPI), malate dehydrogenase (MDH), lactate dehydrogenase (LDH) and pyruvate carboxylase (PC). Lactate and pyruvate was also determined. ResultsA decrease in malate dehydrogenase was observed in groupI in the baseline samples (2196±348 groupS vs 644±192 groupI, P<.05). PC was increased in both samples in groupI (baseline: 1.80±1.27 vs 3.16±2.25; alprostadil: 6.72±2.13 vs 8.16±3.63, groupS vs groupI, respectively, P<.05). No changes were observed in pyruvate and lactate. DiscussionDecreased MDH in ischemic muscle suggests a Krebs cycle reduction. Alprostadil stimulates the expression of PC, which leads to oxaloacetate production. This product is inserted in Krebs cycle, improving energy obtaining. In this manner, Krebs cycle can work partially in ischemic muscle.

Responsiveness to botulinum toxin type A in muscles of complex regional pain patients with tonic dystonia

Tonic dystonia of the limbs in complex regional pain syndrome (CRPS) is associated with considerable disability. Treatment options are scarce. Botulinum toxin (BoNT) is sometimes used, but the effect is often said to be disappointing. However, this notion stems from case reports and clinicians' opinions but has never been formally studied. We therefore investigated responsiveness to BoNT in CRPS patients with tonic dystonia. We injected the extensor digitorum brevis (EDB) muscle with BoNT-A in 17 patients with CRPS and tonic dystonia to compare the response between affected and unaffected legs. We also investigated the right legs of 17 healthy controls. Responsiveness was defined as a decrease of the amplitude of the compound muscle action potential (CMAP) of >20% from baseline 2 weeks after BoNT-A injection. We controlled for a temperature effect on BoNT efficacy by measuring skin temperature hourly directly above the EDB muscle in the first 2 weeks. CMAP amplitude decreased >20% after injection on the affected side in 16 of 17 CRPS patients, similar to the response in unaffected legs (12/13) or legs of controls (17/17). The degree of CMAP reduction was significantly smaller in patients than in controls (56.0 ± 22.3 vs. 70.6 ± 14.6%; p = 0.031). This may be due to a lower physical activity level and a greater difficulty to localize the EDB muscle properly in affected legs. The decrease in CMAP amplitude was not related to skin temperature. Contrary to the prevailing opinion, BoNT-A has a normal, although perhaps slightly lower efficacy in CRPS patients with dystonia.

Comparison between botulinum neurotoxin type A2 and type A1 by electrophysiological study in healthy individuals

Botulinum neurotoxin type A1 (BoNTs/A1) and type B (BoNT/B) have been used for treating hyperactive muscle contractions. In the present study, we compared the effect of botulinum neurotoxin subtype A2 (6.5 mouse LD50 units A2 neurotoxin, A2NTX) and onabotulinumtoxinA (10 mouse LD50 units BoNT/A1 product) by measuring the compound muscle action potentials (CMAPs) before and after administration.In total, 8 healthy subjects were examined in the present study. A2NTX was injected into the extensor digitorum brevis (EDB) muscle, followed by onabotulinumtoxinA injection into the contralateral EDB muscle after 16 weeks. The CMAP amplitudes from the EDB, abductor hallucis (AH), and abductor digiti minimi pedis (ADM) muscles were measured after each BoNT injection on days 1, 3, 7, 14, 28, 56, 84, and 112 to assess the effect of the toxin. On day 14, both A2NTX and onabotulinumtoxinA produced an approximately 70% decline in EDB CMAP amplitude compared to the baseline values; significant reduction of the CMAP continued through day 112. The CMAP amplitudes from neighboring muscles (AH and ADM) remained intact throughout the study period, except for a slight but significant drop at day 28 after onabotulinumtoxinA injection compared to A2NTX. The current findings indicate that small doses (6.5 units and 10 units) of A2NTX and onabotulinumtoxinA have at least comparable onset and duration of action, although similar clinical effects were obtained with lower dose using A2NTX.

Extensor digitorum brevis flap on the treatment of lower limb injuries.

OBJECTIVE: To describe our pioneer national experience with 11 patients with soft tissue defects in the distal 1/3 of the leg, ankle and forefoot treated with extensor digitorum brevis muscle flap (EDB). METHODS: Between November 2009 and July 2012 11 patients were operated with the flap technique. We operated nine men and two women aged between 10 and 66 years. The surgical indications were acute trauma in four patients and post-traumatic osteomyelitis in seven patients. The small defects were covered ranging from 3x3 to 6x3 cm. The patch was applied with proximal stalk in most cases. RESULTS: Complete healing and infectious cure were obtained in all cases, despite one loss. CONCLUSION: The EDB flap is a feasible and safe technique to repair foot, ankle and distal leg losses. Suffering, dehiscence and delayed healing of the EDB end flap donor area may, however, occur. L-shaped incisions should be avoided for muscle lifting. Level of Evidence IV, Case series.

Axon Count and Sympathetic Skin Responses in Lumbosacral Radiculopathy

Background and PurposeElectrodiagnostic studies can be used to confirm the diagnosis of lumbosacral radiculopathies, but more sensitive diagnostic methods are often needed to measure the ensuing motor neuronal loss and sympathetic failure.MethodsTwenty-six patients with lumbar radiculopathy and 30 controls were investigated using nerve conduction studies, motor unit number estimation (MUNE), testing of the sympathetic skin response (SSR), quantitative electromyography (QEMG), and magnetic resonance myelography (MRM).ResultsUsing QEMG as the gold standard, the sensitivity and specificity of MUNE for the abductor hallucis longus muscle were 71.4% and 70%, respectively. While they were 75% and 68.8%, respectively, when used MRM as gold standard. The sensitivity and specificity of MUNE for the extensor digitorum brevis muscle were 100% and 84.1%, respectively, when the peroneal motor amplitude as the gold standard. The SSR latency was slightly longer in the patients than in the controls.ConclusionsMUNE is a simple and sensitive test for evaluating autonomic function and for diagnosing lumbosacral radiculopathy in patients. MUNE could be used routinely as a guide for the rehabilitation of patients with radiculopathies. SSR measurements may reveal subtle sympathetic abnormalities in patients with lumbosacral radiculopathy.