Recovery of neurophysiological measures in post-COVID fatigue: a 12-month longitudinal follow-up study.

One of the major consequences of the COVID-19 pandemic has been the significant incidence of persistent fatigue following resolution of an acute infection (i.e. post-COVID fatigue). We have shown previously that, in comparison to healthy controls, those suffering from post-COVID fatigue exhibit changes in muscle physiology, cortical circuitry, and autonomic function. Whether these changes preceded infection, potentially predisposing people to developing post-COVID fatigue, or whether the changes were a consequence of infection was unclear. Here we present results of a 12-month longitudinal study of 18 participants from the same cohort of post-COVID fatigue sufferers to investigate these correlates of fatigue over time. We report improvements in self-perception of the impact of fatigue via questionnaires, as well as significant improvements in objective measures of peripheral muscle fatigue and autonomic function, bringing them closer to healthy controls. Additionally, we found reductions in muscle twitch tension rise times, becoming faster than controls, suggesting that the improvement in muscle fatigability might be due to a process of adaptation rather than simply a return to baseline function.

Pregabalina preoperatoria previene las fasciculaciones y mialgias inducidas por succinilcolina: metaanálisis de ensayos aleatorizados / Preoperative pregabalin prevents succinylcholine-induced fasciculations and myalgias: A meta-analysis of randomized trials

La succinilcolina es el bloqueador neuromuscular de referencia para la inducción de secuencia rápida. Sin embargo, su uso se asocia a fasciculaciones y mialgias. Se realizó una revisión sistemática y un metaanálisis. Se incluyeron ensayos clínicos controlados aleatorizados comparando gabapentinoides frente a placebo, para la prevención de fasciculaciones y mialgias inducidas por succinilcolina. Se incluyeron seis estudios clínicos aleatorizados. El número total de pacientes fue de 481, de los cuales 241 se incluyeron en el grupo de intervención y 240 en el grupo de placebo. Los gabapentinoides redujeron la incidencia de mialgia inducida por succinilcolina (RR=0,69; IC95%: 0,56-0,84; p<0,001), que siguió siendo estadísticamente significativa para pregabalina (RR=0,71; IC95%: 0,54-0,93; p=0,013) y gabapentina (RR=0,61; IC95%: 0,45-0,82; p=0,001) por separado. No hubo diferencia entre los grupos en cuanto a fasciculaciones (RR=0,92; IC95%: 0,82-1,03; p=0,148). El uso preoperatorio de gabapentinoides se asocia a una menor incidencia de mialgias inducidas por succinilcolina dentro de las primeras 24horas posteriores al procedimiento. (AU)

Succinylcholine is the gold standard neuromuscular blocker for rapid sequence induction, however, its use is associated with fasciculations and myalgias. A systematic review and meta-analysis including randomized controlled clinical trials was performed comparing gabapentinoids versus placebo for the prevention of fasciculations and succinylcholine-induced myalgias. Six randomized clinical studies were included. The total number of patients was 481, of which 241 were in the intervention group and 240 in the placebo group. Gabapentinoids reduced the incidence of succinylcholine-induced myalgia (RR=.69; 95%CI: .56-.84; P<.001), which remained statistically significant for pregabalin (RR=.71; 95%CI: .54-.93; P=.013) and gabapentin (RR=.61; 95%CI: .45-.82; P=.001) separately. There was no difference between the groups in fasciculations (RR=.92; 95%CI: .82-1.03; P=.148). Preoperative use of gabapentinoids is associated with lower incidence of succinylcholine-induced myalgias within the first 24hours after the procedure. (AU)

Neuromuscular ultrasound changes in unilateral symptomatic subacute lumbosacral radiculopathy: A prospective simple blinded cohort study.

INTRODUCTION/AIMS: Lumbosacral radiculopathy (LR) is a common disorder. Neuromuscular ultrasound (NMU) is a rapidly evolving technique for the investigation of peripheral nerve and muscle disorders, but studies using NMU in LR are lacking. The aim of the present study was to investigate ultrasonographic neuromuscular changes distant from root compression in patients with subacute to chronic compressive LR with motor impairment. METHODS: Patients with unilateral subacute to chronic L4, L5, or S1 radiculopathy with motor impairment and confirmed by magnetic resonance imaging were included. The sciatic and femoral nerve cross-sectional areas (CSA), the CSA of lower limb muscles, and muscle fasciculation detection rate were assessed using a pre-specified neuromuscular ultrasound evaluation with blinded side-to-side comparison. RESULTS: Of the 18 included patients, 66% were male and the mean age was 51 years. Overall, 16.7% had L4, 55.5% L5, and 27.8% S1 radiculopathy, mostly due to disc herniation (83%). Sciatic nerve CSA of the symptomatic side was increased (61.4 mm2 vs. 51.3 mm2; p = .001), and the fasciculation detection rate was higher in the affected muscles (delta = 13%, p = .007) compared to unaffected ones. Muscle CSA in affected and nonaffected muscles was decreased on the symptomatic side. DISCUSSION: NMU evaluation in patients with symptomatic subacute to chronic LR revealed sciatic nerve enlargement distant from nerve root compression and higher fasciculation rates. These structural findings on NMU might be due to an axonal repair mechanism and an inflammatory response with endoneurial edema induced by ongoing nerve damage and potentially reflect progressive axonal loss.

Swine Pudendal Nerve as a Model for Neuromodulation Studies to Restore Lower Urinary Tract Dysfunction.

Lower urinary tract dysfunction, such as incontinence or urinary retention, is one of the leading consequences of neurological diseases. This significantly impacts the quality of life for those affected, with implications extending not only to humans but also to clinical veterinary care. Having motor and sensory fibers, the pudendal nerve is an optimal candidate for neuromodulation therapies using bidirectional intraneural prostheses, paving the way towards the restoration of a more physiological urination cycle: bladder state can be detected from recorded neural signals, then an electrical current can be injected to the nerve based on the real-time need of the bladder. To develop such prostheses and investigate this novel approach, animal studies are still required since the morphology of the target nerve is fundamental to optimizing the prosthesis design. This study aims to describe the porcine pudendal nerve as a model for neuromodulation studies aiming at restoring lower urinary tract dysfunction. Five male farm pigs were involved in the study. First, a surgical procedure to access the porcine pudendal nerve without muscle resection was developed. Then, an intraneural interface was implanted to confirm the presence of fibers innervating the external urethral sphincter by measuring its electromyographic activity. Finally, the morphophysiology of the porcine pudendal nerve at the level of surgical exposure was described by using histological and immunohistochemical characterization. This analysis confirmed the fasciculate nature of the nerve and the presence of mixed fibers with a spatial and functional organization. These achievements pave the way for further pudendal neuromodulation studies by using a clinically relevant animal model with the potential for translating the findings into clinical applications.

Right Brain: The Strangeness of a Good Diagnosis.

Coffee, black with a spritz of milk. I enjoyed routine, and today was no different. We were on the 12th floor of the "tower", as our hospital is lovingly called. It was my second year of residency, and I was charged with admissions to our neurological ward. Sighing with the expectation of a long day, I walked over to our patients. The first was a woman in her sixties. She complained of trouble swallowing for the past 2 months that was getting worse. She was otherwise healthy. Asked about her social background, she looked over to her husband with an impish grin and replied: "happily married for almost thirty years." Physical examination was next. There was no apparent muscle weakness, but, strangely enough, the Babinski sign was clearly positive. Looking at her tongue, I noticed a single, delicate strain of muscle twitching. It was subtle, but impossible to miss. The twitching was adamant. It was not rhythmic, but it was unrelenting. I could not help but stare, and eventually, the patient closed her mouth, looking at me puzzled. I did not make the connection at first. But, walking back to our room, I realized that the concert of neurological dysfunction was spelling out the diagnosis. I caught myself feeling excited despite my knowledge of the potential outcome. Reporting my findings to my consultant, I remember him saying: "Sure sounds like amyotrophic lateral sclerosis, but we still have to complete our work-up." And so we did, dutifully.

Patient With Rigidity and Fasciculations: Steroid-Responsive Presentation of Anti-IgLON5 Disease

An 82-year-old man presented with 2-year lasting widespread muscular fasciculations, cramps, and limb stiffness, with spontaneous movements in the right lower limb, unsteady gait (Video 1), and falls. Neurophysiologic studies disclosed signs of neuromuscular hyperexcitability. CSF analysis showed high tau protein concentration (543 pg/mL; reference values, <404) and unique-to-CSF oligoclonal bands. Serum and CSF anti-IgLON5 antibodies were positive (Figure 1). He carried the anti-IgLON5 disease-associated HLA-DRB1*10:01 allele.1 Brain MRI, thoracoabdominal CT, whole-body FDG-PET, and video-polysomnography were unremarkable. No sleep disturbances, bulbar symptoms, parkinsonism, or dementia were detected. Intravenous methylprednisolone (500 mg/d for 5 days), followed by oral benzodiazepines, prompted rapid functional recovery, with limb stiffness and gait improvement (Video 1), which persisted at 6-month follow-up. Anti-IgLON5 disease has progressive course and protean clinical presentations,2 representative, in our patient, for overlapping signs and symptoms of neuromuscular hyperexcitability and rigidity. Identification of rare phenotypes is important because prompt recognition and treatment can improve prognosis.

Somatostatin affects GnRH neuronal development and migration and stimulates olfactory-related fiber fasciculation.

Transient expression of somatostatin (SST) has been observed in the olfactory epithelium (OE) and nerves of chick embryos. Intense expression of SST in these regions on embryonic days (E) 5-8 coincides with the migration of neurons producing gonadotropin-releasing hormone (GnRH) from the OE to the forebrain (FB), suggesting that SST plays a role in the development of GnRH neurons. Using in ovo electroporation of small interfering RNA, we found that the suppression of SST mRNA in the olfactory placode (OP) of E3.5 chick embryos significantly reduced the number of GnRH and Islet-1-immunoreactive neurons in the nasal region without affecting the entry of GnRH neurons into the FB at E5.5-6. SST knockdown did not lead to changes in the number of apoptotic, proliferating, or HuC/D-positive neuronal cells in the OE; therefore, it is possible that SST is involved in the neurogenesis/differentiation of GnRH neurons and OP-derived GnRH-negative migratory neurons. In whole OP explant cultures, we also found that SST or its analog octreotide treatment significantly increased the number of migratory GnRH neurons and the migratory distance from the explants. The co-application of an SST antagonist blocked the octreotide-induced increase in the number of GnRH neurons. Furthermore, the fasciculation of polysialylated neural cell adhesion molecule-immunoreactive fibers emerging from the explants was dependent on octreotide. Taken together, our results provide evidence that SST exerts facilitatory effects on the development of neurons expressing GnRH or Islet-1 and on GnRH neuronal migration, in addition to olfactory-related fiber fasciculation.

Differentiation Between Amyotrophic Lateral Sclerosis and Mimics Using Quantitative Analysis of Fsciculation with Muscle Ultrasound.

Objective To determine the diagnostic accuracy of the intensity of fasciculation evaluated by muscle ultrasound in the differential diagnosis of amyotrophic lateral sclerosis (ALS). Methods We prospectively recruited patients who had ALS and neuropathy-radiculopathy attending Peking Union Medical College Hospital from 2017 to 2020. Healthy adults from a community were recruited as healthy controls. Muscle strength was assessed using the Medical Research Council (MRC) scale. At the first visit to the hospital, patients were assessed for maximal grade of fasciculations, total fasciculation score, and fasciculation grade in 16 muscle groups of bilateral upper and lower limbs using ultrasonography. The sensitivity and specificity of maximal grade of fasciculations, total fasciculation score, and fasciculation grade for the diagnosis of ALS were assessed by receiver operating characteristic analyses. Results The percentage of limb muscles with a maximal fasciculation grade higher than grade 2 in ALS patients and neuropathy-radiculopathy patients was 84.9% and 9.8%, respectively (χ2 = 172.436, P < 0.01). Of the 16 limb muscles detected, the total fasciculation score [median (interquartile range)] was 29 (15, 41) in ALS patients and 3 (0, 8) in neuropathy-radiculopathy patients (Z = 9.642, P < 0.001). Remarkable fasciculations were seen in ALS patients whose muscles with a MRC score ranging from 2 to 4, followed by patients with MRC score 5, and then in those with MRC score 0 and 1. The sensitivity and specificity of total fasciculation score for diagnosis of ALS were 80.6% and 93.4%, respectively (cut-off value 14). In patients with ALS, for muscles with MRC score 4 and 5, the percentage of muscles with fasciculation grades ≥ 3 was 42.3% and 24.1% respectively, while in neuropathy-radiculopathy patients, the percentage for muscles with MRC score 4 and 5 was only 1.7% and 0, respectively. Conclusion A combined analysis of fasciculation intensity and MRC score of the limb muscles may be helpful for differential diagnosis of ALS.

Quantitative sonographic assessment of muscle thickness and fasciculations distribution is a sensitive tool for neuromuscular disorders.

INTRODUCTION: Loss of muscle thickness can be demonstrated in a wide spectrum of neuromuscular disorders, while fasciculations are more frequent in amyotrophic lateral sclerosis (ALS). In the current study, we aimed to determine the sensitivity and specificity of quantitative sonographic assessment of muscle thickness and the presence of fasciculations for diagnosing various neuromuscular disorders. METHODS: The thickness and the presence of fasciculations in eight muscles were determined by sonography in patients with myopathy (22), polyneuropathy (36), ALS (91), and spinal muscular atrophy (SMA) (31) and compared to normative values determined in 65 heathy control subjects. RESULTS: Reduced muscle thickness in at least one relaxed muscle showed 92-100% sensitivity for diagnosing a neuromuscular disease, with a specificity of 85% for differentiating patients from heathy controls (AUC = 0.90). Subtracting distal from proximal muscle thickness may differentiate between myopathy and polyneuropathy. Fasciculations in ≥1 proximal muscle showed good diagnostic accuracy (AUC = 0.87) for diagnosing ALS. DISCUSSION: Sonographic assessment of muscle thickness is a sensitive tool for diagnosing a wide spectrum of neuromuscular diseases, and may facilitate diagnosis even in patients with normal strength on neurological examination, while the presence of fasciculations in proximal muscles may facilitate ALS diagnosis.

Central projections from Johnston's organ in the locust: Axogenesis and brain neuroarchitecture.

Johnston's organ (Jo) acts as an antennal wind-sensitive and/or auditory organ across a spectrum of insect species and its axons universally project to the brain. In the locust, this pathway is already present at mid-embryogenesis but the process of fasciculation involved in its construction has not been investigated. Terminal projections into the fine neuropilar organization of the brain also remain unresolved, information essential not only for understanding the neural circuitry mediating Jo-mediated behavior but also for providing comparative data offering insights into its evolution. In our study here, we employ neuron-specific, axon-specific, and epithelial domain labels to show that the pathway to the brain of the locust is built in a stepwise manner during early embryogenesis as processes from Jo cell clusters in the pedicel fasciculate first with one another, and then with the two tracts constituting the pioneer axon scaffold of the antenna. A comparison of fasciculation patterns confirms that projections from cell clusters of Jo stereotypically associate with only one axon tract according to their location in the pedicellar epithelium, consistent with a topographic plan. At the molecular level, all neuronal elements of the Jo pathway to the brain express the lipocalin Lazarillo, a cell surface epitope that regulates axogenesis in the primary axon scaffold itself, and putatively during fasciculation of the Jo projections to the brain. Central projections from Jo first contact the primary axon scaffold of the deutocerebral brain at mid-embryogenesis, and in the adult traverse mechanosensory/motor neuropils similar to those in Drosophila. These axons then terminate among protocerebral commissures containing premotor interneurons known to regulate flight behavior.

[Clinical and neuroelectrophysiological characteristics of primary peripheral nerve hyperexcitability syndrome].

Objective: To investigate the clinical and neuroelectrophysiological characteristics of patients with primary peripheral nerve hyperexcitability syndrome (PNHS). Methods: The clinical data of 20 patients who were diagnosed with PNHS in Beijing Tiantan Hospital from April 2016 to January 2023 were retrospectively collected. All patients underwent neuroelectrophysiological examinations. Clinical and electrophysiological characteristics were compared between the antibody positive and antibody negative groups, according to serum and cerebrospinal fluid anti-contactin-associated protein-like 2 (CASPR2) and/or anti-leucine-rich glioma-inactivated protein 1 (LGI-1) antibodies. Results: There were 12 males and 8 females, with a mean age of (44.0±17.2) years and the disease course of [M (Q1, Q3)] 2.3 (1.1, 11.5) months. Motor symptoms included fasciculations, myokymia, muscle pain, cramps, and stiffness. These symptoms were commonly seen in the lower limbs (17 patients), followed by upper limbs (11 patients), face (11 patients) and trunk (9 patients). Nineteen (19/20) patients had sensory abnormalities and/or autonomic dysfunction, 13 patients had central nervous system involvement, and 5 patients had concomitant lung cancer or thymic lesions. The characteristic spontaneous potentials on needle electromyography (EMG) were myokymia potential (19 patients), fasciculation potential (12 patients), spastic potential (3 patients), neuromyotonic potential (1 patients), etc, which were commonly seen in the lower limb muscles, especially the gastrocnemius muscle(12 patients). After-discharge potential was found in 8 patients, and 7 were in the tibial nerve. Seven patients had positive serum anti-CASPR2 antibodies, and 3 of them had concomitant anti-LGI1 antibodies. And 1 patient had positive serum anti-LGI1 antibody alone. Compared with patients in the antibody negative group (n=12), the patients who had anti-VGKC complex antibodies (n=8) had a shorter course of disease [M (Q1, Q3): 1.8 (1, 2) months vs 9.5 (3.3, 20.3) months, P=0.012], higher incidence of after-discharge potential (6/8 vs 2/12, P=0.019). The immunotherapy regimen (multi-dru, single-drug, no immunotherapy: 6, 2, 0 patients) in antibody-positive patients was different from the antibody-negative group (3, 6, 3 patients, U=21.00, P=0.023). Conclusions: The symptoms of motor nerve hyperexcitation, characteristic EMG spontaneous potentials and after-discharge potentials in PNHS patients are most commonly seen in the lower limbs. Attention should be paid to concomitant sensory and autonomic nerve hyperexcitation. PNHS patients with positive serum anti-CASPR2 antibodies may require immunotherapy with multiple drugs.

Clinical study of magnetic resonance imaging-based texture analysis and fasciculation of the lateral pterygoid muscle in young patients with temporomandibular disorder.

OBJECTIVE: We aimed to evaluate the effectiveness of clinical examination combined with texture analysis of magnetic resonance imaging (MRI) and fasciculation patterns of the lateral pterygoid muscle (LPM) in distinguishing among the different anatomic causes of temporomandibular disorder. METHODS: We divided the patients into four groups: healthy control (HC), disk without displacement (DWoD), disk displacement with reduction (DDWR), and disk displacement without reduction (DDWoR). Demographic information and clinical symptoms of patients in each group were recorded. LPM textures were compared among groups. LPM fasciculation was examined. P<0.05 indicated significant difference. RESULTS: Several clinical symptoms and signs, but not age or sex, differed significantly among groups. Oblique sagittal planar MRI revealed significant differences in the parameters of Angular Second Moment, Contrast, Correlation, Inverse Difference Moment, and Entropy between the healthy controls and the 3 patient groups. MRI of the patients, both without and with disk displacement, demonstrated relative uniformity in gray distribution and correlation of gray values, with greater complexity but an unclear texture and no obvious regularity. The proportion of type B LPM fascicles was significantly higher in the DDWR and DDWoR groups CONCLUSION: Temporomandibular disorder, without and with disk displacement, is associated with clinical symptoms and texture analysis values that differ from healthy muscle. The types of LPM fascicles are related to the position of the articular disk.

FEZ1 Plays Dual Roles in Early HIV-1 Infection by Independently Regulating Capsid Transport and Host Interferon-Stimulated Gene Expression.

Fasciculation and elongation factor zeta 1 (FEZ1), a multifunctional kinesin-1 adaptor, binds human immunodeficiency virus type 1 (HIV-1) capsids and is required for efficient translocation of virus particles to the nucleus to initiate infection. However, we recently found that FEZ1 also acts as a negative regulator of interferon (IFN) production and interferon-stimulated gene (ISG) expression in primary fibroblasts and human immortalized microglial cell line clone 3 (CHME3) microglia, a natural target cell type for HIV-1 infection. This raises the question of whether depleting FEZ1 negatively affects early HIV-1 infection through effects on virus trafficking or IFN induction or both. Here, we address this by comparing the effects of FEZ1 depletion or IFN-ß treatment on early stages of HIV-1 infection in different cell systems with various IFN-ß responsiveness. In either CHME3 microglia or HEK293A cells, depletion of FEZ1 reduced the accumulation of fused HIV-1 particles around the nucleus and suppressed infection. In contrast, various doses of IFN-ß had little to no effect on HIV-1 fusion or the translocation of fused viral particles to the nucleus in either cell type. Moreover, the potency of IFN-ß's effects on infection in each cell type reflected the level of induction of MxB, an ISG that blocks subsequent stages of HIV-1 nuclear import. Collectively, our findings demonstrate that loss of FEZ1 function impacts infection through its roles in two independent processes, as a direct regulator of HIV-1 particle transport and as a regulator of ISG expression. IMPORTANCE As a hub protein, fasciculation and elongation factor zeta 1 (FEZ1) interacts with a range of other proteins involved in various biological processes, acting as an adaptor for the microtubule (MT) motor kinesin-1 to mediate outward transport of intracellular cargoes, including viruses. Indeed, incoming HIV-1 capsids bind to FEZ1 to regulate the balance of inward/outward motor activity to ensure net forward movement toward the nucleus to initiate infection. However, we recently showed that FEZ1 depletion also induces interferon (IFN) production and interferon-stimulated gene (ISG) expression. As such, it remains unknown whether modulating FEZ1 activity affects HIV-1 infection through its ability to regulate ISG expression or whether FEZ1 functions directly, or both. Using distinct cell systems that separate the effects of IFN and FEZ1 depletion, here we demonstrate that the kinesin adaptor FEZ1 regulates HIV-1 translocation to the nucleus independently of its effects on IFN production and ISG expression.

Needle electromyography abnormalities in the upper trapezius muscle in neuromuscular disorders.

BACKGROUND: : Needle electromyography (EMG) abnormalities in the trapezius muscle (TM) can be seen in neuromuscular disorders. The aim was to determine the characteristics of needle EMG abnormalities observed in the TM in neuromuscular disorders. METHODS: The data of patients who applied to the Clinical Neurophysiology Laboratory of University of Health Sciences Adana City Training and Research Hospital between December 2018 and October 2021 were reviewed. Polio survivors, amyotrophic lateral sclerosis (ALS) patients, patients with sensorimotor polyneuropathy, patients with spinal cord lesions involving C2/C3/C4 segments, patients with spinal accessory nerve (SAN) lesions, neuralgic amyotrophy (NA) patients, and patients with myopathy were included. Needle EMG findings of the upper TM of the patients were analyzed. Positive sharp waves, fibrillation potentials, fasciculation potentials, myotonic discharges, and motor unit action potential (MUAP) changes were considered needle EMG abnormalities. RESULTS: Eighty-one polio survivors, 23 ALS patients, 39 patients with sensorimotor polyneuropathy, 10 patients with cervical spinal lesions, eight NA patients, seven patients with SAN lesions, and three patients with myopathy were included in the study. Fifteen (65.2%) ALS patients, 18 (22.2%) polio survivors, three (30%) patients with cervical spinal lesions, two (5.1%) patients with sensorimotor neuropathy, one (12.5%) NA patient, seven (100%) patients with SAN lesions, and two (66.7%) patients with myopathies had at least one needle EMG abnormality in the TM. Fasciculation potentials in the TM were seen in 10 (43.5%) ALS patients. In four patients with SAN lesions and one polio survivor, MUAP could not be obtained from the TM. DISCUSSION: There may be more frequent needle EMG abnormalities, particularly in ALS patients and patients with SAN lesions. Since the number of patients with myopathy included in this study was low, it is difficult to comment on the needle EMG features of the TM for these patients. In addition, this study indicated that fasciculation potentials in the TM are typical in ALS patients and that MUAP may not be obtained from the TM in patients with SAN lesions.

Spectrum of SPTLC1-related disorders: a novel case of 'Ser331 syndrome' that expand the phenotype of hereditary sensory and autonomic neuropathy type 1A and motor neuron diseases.

We report a patient with early-onset hereditary sensory and autonomic neuropathy type 1A (HSAN-1A) who developed a distinct phenotype, with tongue fasciculation and atrophy, due to a mutation at serine 331 in the SPTLC1 gene. HSAN-1A manifestation causing tongue fasciculation and atrophy have been rarely found. Our report adds to the growing evidence of the existence of an overlap between hereditary neuropathy and motor neuron disease caused by pathogenic p.S331Y variant in SPTLC1 gene.

Modulation of Cerebral Function by Muscle Afferent Activity, with Reference to Intravenous Succinylcholine.

Cerebral Function and Muscle Afferent Activity Following Intravenous Succinylcholine in Dogs Anesthetized with Halothane: The Effects of Pretreatment with a Defasciculating Dose of Pancuronium. By WL Lanier, PA Iaizzo, and JH Milde. Anesthesiology 1989; 71:87-95. Reprinted with permission. By the mid-1980s, it was widely assumed that if the depolarizing muscle relaxant, succinylcholine, given IV, produced increases in intracranial pressure, it did so because fasciculations produced increases in intrathoracic and central venous pressures that were transferred to the brain; however, there was no direct evidence that this was true. In contrast, we explored the possibility that the succinylcholine effect on the brain was explained by the afferentation theory of cerebral arousal, which predicts that agents or maneuvers that stimulate muscle stretch receptors will tend to stimulate the brain. Our research in tracheally intubated, lightly anesthetized dogs discovered that IV succinylcholine (which does not cross the blood-brain barrier) produced a doubling of cerebral blood flow that lasted for 30 min and corresponded to activation of the electroencephalogram and increases in intracranial pressure. Later, in our Classic Paper, we were able to assess simultaneously cerebral physiology and afferent nerve traffic emanating from muscle stretch receptors (primarily muscle spindles). We affirmed that the cerebral arousal response to succinylcholine was indeed driven by muscle afferent traffic and was independent of fasciculations or increases in intrathoracic or central venous pressures. Later research in complementary models demonstrated that endogenous movement (e.g., coughing, hiccups) produced a cerebral response very similar to IV succinylcholine, apparently as a result of the same muscle afferent mechanisms, independent of intrathoracic and central venous pressures. Thus, the importance of afferentation theory as a driver of the cerebral state of arousal and cerebral physiology during anesthesia was affirmed.

Chemical and mechanical control of axon fasciculation and defasciculation.

Neural networks are constructed through the development of robust axonal projections from individual neurons, which ultimately establish connections with their targets. In most animals, developing axons assemble in bundles to navigate collectively across various areas within the central nervous system or the periphery, before they separate from these bundles in order to find their specific targets. These processes, called fasciculation and defasciculation respectively, were thought for many years to be controlled chemically: while guidance cues may attract or repulse axonal growth cones, adhesion molecules expressed at the surface of axons mediate their fasciculation. Recently, an additional non-chemical parameter, the mechanical longitudinal tension of axons, turned out to play a role in axon fasciculation and defasciculation, through zippering and unzippering of axon shafts. In this review, we present an integrated view of the currently known chemical and mechanical control of axon:axon dynamic interactions. We highlight the facts that the decision to cross or not to cross another axon depends on a combination of chemical, mechanical and geometrical parameters, and that the decision to fasciculate/defasciculate through zippering/unzippering relies on the balance between axon:axon adhesion and their mechanical tension. Finally, we speculate about possible functional implications of zippering-dependent axon shaft fasciculation, in the collective migration of axons, and in the sorting of subpopulations of axons.

Fasciculation electromechanical latency is prolonged in amyotrophic lateral sclerosis.

OBJECTIVE: In amyotrophic lateral sclerosis (ALS), motor neurons become hyperexcitable and spontaneously discharge electrical impulses causing fasciculations. These can be detected by two noninvasive methods: high-density surface electromyography (HDSEMG) and muscle ultrasonography (MUS). We combined these methods simultaneously to explore the electromechanical properties of fasciculations, seeking a novel biomarker of disease. METHODS: Twelve ALS patients and thirteen healthy participants each provided up to 24 minutes of recordings from the right biceps brachii (BB) and gastrocnemius medialis (GM). Two automated algorithms (Surface Potential Quantification Engine and a Gaussian mixture model) were applied to HDSEMG and MUS data to identify correlated electromechanical fasciculation events. RESULTS: We identified 4,197 correlated electromechanical fasciculation events. HDSEMG reliably detected electromechanical events up to 30 mm below the skin surface with an inverse correlation between amplitude and depth in ALS muscles. Compared to Healthy-GM muscles (mean = 79.8 ms), electromechanical latency was prolonged in ALS-GM (mean = 108.8 ms; p = 0.0458) and ALS-BB (mean = 112.0 ms; p = 0.0128) muscles. Electromechanical latency did not correlate with disease duration, symptom burden, sum muscle power score or fasciculation frequency. CONCLUSIONS: Prolonged fasciculation electromechanical latency indicates impairment of the excitation-contraction coupling mechanism, warranting further exploration as a potential novel biomarker of disease in ALS. SIGNIFICANCE: This study points to an electromechanical defect within the muscles of ALS patients.

Benign fasciculation syndrome and migraine aura without headache as possible adverse events after BNT162b2 mRNA vaccination: a web-based survey.

AIM: To determine the characteristics of patients who experienced muscle fasciculations and migraine auras without headache after BNT162b2 immunization. METHODS: In January 2022, we published a case report that described a 48-year-old female patient who experienced muscle twitching and migraine auras without headache following BNT162b2 immunization. A self-administered online survey was sent to people who had written to us and complained of similar symptoms described in the case report (N=20). RESULTS: The survey was completed by 11 participants, of whom 10 reported muscle twitching following BNT162b2 immunization lasting a median of 14 (4-36.5) days. Five of these participants (50%) reported migraine auras without headache. Participants further reported on self-identified triggers that altered the intensity of their symptoms, such as anxiety or caffeine. Fifty percent of participants who got an acute SARS-CoV-2 infection (3/6) experienced increased muscle symptom intensity during the acute phase of the disease. CONCLUSION: To the best of our knowledge, our survey is the first to summarize patients' experiences of these phenomena occurring after BNT162b2 immunization. It is important to note that no causal relationship between vaccination and these phenomena can be inferred.