Liposomal Bupivacaine (Bupigel) Demonstrates Minimal Local Nerve Toxicity in a Rabbit Functional Model.

We previously reported the development of a novel formulation of an ultra-long-acting local anesthetic based on bupivacaine encapsulated in large multivesicular liposomes (Bupisomes) embedded in hydrogel. This formulation (Bupigel) prolonged bupivacaine release from the formulation in dissolution-like studies in vitro and analgesia in vivo in mouse, rat, and pig models. In this study we assessed Bupigel neurotoxicity on rabbit sciatic nerve using histopathology and electrophysiologic testing. Sciatic nerves of both hind limbs were injected dropwise with different formulations. Nerve conduction studies and needle electromyography two weeks after perineural administration showed signs of neural damage after injection of free lidocaine and bupivacaine, while there was no sign of neural damage after injection with saline, demonstrating the validity of the method. This test also did not show evidence of motor or sensory nerve damage after injection with liposomal bupivacaine at a dose 10-times higher than free bupivacaine. Histologically, signs of neural damage could be observed with lidocaine. Nerves injected with Bupigel showed mild signs of inflammation and small residues of hydrogel in granulomas, indicating a long residence time of the hydrogel at the site of injection, but no histopathological signs of nerve damage. This demonstrated that early signs of neural damage were detected electrophysiologically, showing the usefulness and sensitivity of electrodiagnostic testing in detection of neural damage from new formulations.

Impaired Regeneration in Dystrophic Muscle-New Target for Therapy.

Muscle stem cells (MuSCs), known as satellite cells (SCs) have an incredible ability to regenerate, which enables the maintenance and growth of muscle tissue. In response to damaging stimuli, SCs are activated, proliferate, differentiate, and fuse to repair or generate a new muscle fiber. However, dystrophic muscles are characterized by poor muscle regeneration along with chronic inflammation and fibrosis. Indications for SC involvement in muscular dystrophy pathologies are accumulating, but their contribution to muscle pathophysiology is not precisely understood. In congenital muscular dystrophy type 1A (LAMA2-CMD), mutations in Lama2 gene cause either complete or partial absence in laminin-211 protein. Laminin-211 functions as a link between muscle extracellular matrix (ECM) and two adhesion systems in the sarcolemma; one is the well-known dystrophin-glycoprotein complex (DGC), and the second is the integrin complex. Because of its protein interactions and location, laminin-211 has a crucial role in muscle function and survival by maintaining sarcolemma integrity. In addition, laminin-211 is expressed in SCs and suggested to have a role in SC proliferation and differentiation. Downstream to the primary defect in laminin-211, several secondary genes and pathways accelerate disease mechanism, while at the same time there are unsuccessful attempts to regenerate as compensation for the dystrophic process. Lately, next-generation sequencing platforms have advanced our knowledge about the secondary events occurring in various diseases, elucidate the pathophysiology, and characterize new essential targets for development of new treatment strategies. This review will mainly focus on SC contribution to impaired regeneration in muscular dystrophies and specifically new findings suggesting SC involvement in LAMA2-CMD pathology.

Small-fiber neuropathy associated with autoinflammatory syndromes in children and adolescents.

INTRODUCTION: Small-fiber neuropathy is rare in children. It has been associated with several autoimmune disorders, but there are no reports of an autoinflammatory etiology. METHODS: The data of four children/adolescents presenting with erythromelalgia and neuropathic pain from 2014 to 2019 were collected retrospectively from the electronic database of a pediatric medical center. RESULTS: Results of clinical and/or electrophysiological evaluation excluded large nerve fiber involvement. Skin biopsy results confirmed small-fiber neuropathy. According to genetic analysis, two patients were heterozygous and one was homozygous for mutations in the familial Mediterranean fever (MEFV) gene. Behcet disease was diagnosed in the fourth patient. Treatment with anti-interleukin-1 agents, intravenous immunoglobulin, and glucocorticoids was beneficial. DISCUSSION: The diagnosis of small-fiber neuropathy should be considered in children/adolescents presenting with erythromelalgia. A thorough investigation is required to reveal the underlying disorder. Clinicians should be alert to the peripheral neurological manifestations of autoinflammatory syndromes because effective treatments are available.

Improvement of motor conduction velocity in hereditary neuropathy of LAMA2-CMD dy2J/dy2J mouse model by glatiramer acetate.

OBJECTIVE: Glatiramer acetate (GA), an agent modulating the immune system, has been shown to cause significantly improved mobility and hind limb muscle strength in the dy2J/dy2J mouse model for LAMA2-congenital muscular dystrophy (LAMA2-CMD). In view of these findings and the prominent peripheral nervous system involvement in this laminin-α2 disorder we evaluated GA's effect on dy2J/dy2J motor nerve conduction electrophysiologically. METHODS: Left sciatic-tibial motor nerve conduction studies were performed on wild type (WT) mice (n = 10), control dy2J/dy2J mice (n = 11), and GA treated dy2J/dy2J mice (n = 10) at 18 weeks of age. RESULTS: Control dy2J/dy2J mice average velocities (34.49 ±â€¯2.15 m/s) were significantly slower than WT (62.57 ±â€¯2.23 m/s; p < 0.0005), confirming the clinical observation of hindlimb paresis in dy2J/dy2J mice attributed to peripheral neuropathy. GA treated dy2J/dy2J mice showed significantly improved average sciatic-tibial motor nerve conduction velocity versus control dy2J/dy2J (50.35 ±â€¯2.9 m/s; p < 0.0005). CONCLUSION: In this study we show for the first time improvement in motor nerve conduction velocity of LAMA2-CMD dy2J/dy2J mouse model's hereditary peripheral neuropathy following GA treatment. SIGNIFICANCE: This study suggests a possible therapeutic effect of glatiramer acetate on hereditary peripheral neuropathy in this laminin-α2 disorder.

Pax7, Pax3 and Mamstr genes are involved in skeletal muscle impaired regeneration of dy2J/dy2J mouse model of Lama2-CMD.

Congenital muscular dystrophy type-1A (Lama2-CMD) and Duchenne muscular dystrophy (DMD) result from deficiencies of laminin-α2 and dystrophin proteins, respectively. Although both proteins strengthen the sarcolemma, they are implicated in clinically distinct phenotypes. We used RNA-deep sequencing (RNA-Seq) of dy2J/dy2J, Lama2-CMD mouse model, skeletal muscle at 8 weeks of age to elucidate disease pathophysiology. This study is the first report of dy2J/dy2J model whole transcriptome profile. RNA-Seq of the mdx mouse model of DMD and wild-type (WT) mouse was carried as well in order to enable a novel comparison of dy2J/dy2J to mdx. A large group of shared differentially expressed genes (DEGs) was found in dy2J/dy2J and mdx models (1834 common DEGs, false discovery rate [FDR] < 0.05). Enrichment pathway analysis using ingenuity pathway analysis showed enrichment of inflammation, fibrosis, cellular movement, migration and proliferation of cells, apoptosis and necrosis in both mouse models (P-values 3E-10-9E-37). Via canonical pathway analysis, actin cytoskeleton, integrin, integrin-linked kinase, NF-kB, renin-angiotensin, epithelial-mesenchymal transition, and calcium signaling were also enriched and upregulated in both models (FDR < 0.05). Interestingly, significant downregulation of Pax7 was detected in dy2J/dy2J compared to upregulation of this key regeneration gene in mdx mice. Pax3 and Mamstr genes were also downregulated in dy2J/dy2J compared to WT mice. These results may explain the distinct disease course and severity in these models. While the mdx model at that stage shows massive regeneration, the dy2J/dy2J shows progressive dystrophic process. Our data deepen our understanding of the molecular pathophysiology and suggest new targets for additional therapies to upregulate regeneration in Lama2-CMD.

Biallelic variants in AGTPBP1, involved in tubulin deglutamylation, are associated with cerebellar degeneration and motor neuropathy.

The ATP/GTP-Binding Protein 1 (AGTPBP1) gene (OMIM *606830) catalyzes deglutamylation of polyglutamylated proteins, and its deficiency manifests by cerebellar ataxia and peripheral neuropathy in mice and lower motor neuron-like disease in sheep. In the mutant mice, cerebellar atrophy due to Purkinje cell degeneration is observed, likely due to increased tubulin polyglutamylation in affected brain areas. We report two unrelated individuals who presented with early onset cerebellar atrophy, developmental arrest with progressive muscle weakness, and feeding and respiratory difficulties, accompanied by severe motor neuronopathy. Whole exome sequencing followed by segregation analysis in the families and cDNA studies revealed deleterious biallelic variants in the AGTPBP1 gene. We conclude that complete loss-of-function of AGTPBP1 in humans, just like in mice and sheep, is associated with cerebellar and motor neuron disease, reminiscent of Pontocerebellar Hypoplasia Type 1 (PCH1).

Atypical Clinical Presentations of Pediatric Acute Immune-Mediated Polyneuropathy.

Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis in children. During the acute phase, the disorder can be life-threatening by involving the respiratory muscles and the autonomic nervous system. Nevertheless, the prognosis is good, and most children achieve full recovery. The aim of this study was to characterize the clinical and electrophysiologic findings in children with Guillain-Barré syndrome referred to a tertiary center in Israel. A retrospective database review from 2009 to 2015 identified 39 children. Data on clinical presentation, respiratory complications, and long-term neurologic outcomes were collected. Atypical clinical findings at admission included asymmetric weakness in 23%, nonascending weakness in 30%, and normal deep tendon reflexes in 28%. Eight children were later diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Electrophysiologic findings, available in 12 patients with Guillain-Barré syndrome, revealed acute inflammatory demyelinating polyradiculoneuropathy (AIDP) in 4 (33.5%), AIDP with secondary axonal changes in 3 (25%), and acute motor axonal neuropathy (AMAN) subtype in 4 (33.5%); 8% had no abnormal findings. On follow-up, 71% of the children with Guillain-Barré syndrome fully recovered compared to 14% of the children with CIDP. Corresponding rates of neurologic sequelae were 29% and 86%. Clinicians should be alert to the atypical presenting symptoms of Guillain-Barré syndrome, which occur in a significant proportion of children.

Liposomal steroid nano-drug is superior to steroids as-is in mdx mouse model of Duchenne muscular dystrophy.

Glucocorticosteroids are the most efficacious anti-inflammatory agents and the gold standard treatment in Duchenne muscular dystrophy (DMD). However, their chronic use may lead to severe side effects. We evaluated the use of a novel injectable steroidal nano-drug in mdx mouse model of DMD by comparing the efficacy of nano-liposomes remotely loaded with the steroid prodrug, methylprednisolone hemisuccinate (MPS) with the same steroid as-is, in short (4-weeks) and long-term (58-weeks) treatments. Liposomal-MPS was selectively targeted to the mouse diaphragm, the most dystrophic muscle at early stage of the disease. The bioactivity of the steroidal nano-drug was evidenced by a significant decreased serum TGF-ß and reduced diaphragm macrophage infiltration after short-term treatment. In the long-term, the treatment with liposomal-MPS not only demonstrated improved muscle strength and mobility it also induced lower tibia and lumbar vertebrae osteoporosis indicating much lower bone related adverse effects.

NMO-IgG and AQP4 Peptide Can Induce Aggravation of EAMG and Immune-Mediated Muscle Weakness.

Neuromyelitis optica (NMO) and myasthenia gravis (MG) are autoimmune diseases mediated by autoantibodies against either aquaporin 4 (AQP4) or acetylcholine receptor (AChR), respectively. Recently, we and others have reported an increased prevalence of NMO in patients with MG. To verify whether coexisting autoimmune disease may exacerbate experimental autoimmune MG, we tested whether active immunization with AQP4 peptides or passive transfer of NMO-Ig can affect the severity of EAMG. Injection of either AQP4 peptide or NMO-Ig to EAMG or to naive mice caused increased fatigability and aggravation of EAMG symptoms as expressed by augmented muscle weakness (but not paralysis), decremental response to repetitive nerve stimulation, increased neuromuscular jitter, and aberration of immune responses. Thus, our study shows increased disease severity in EAMG mice following immunization with the NMO autoantigen AQP4 or by NMO-Ig, mediated by augmented inflammatory response. This can explain exacerbation or increased susceptibility of patients with one autoimmune disease to develop additional autoimmune syndrome.

Congenital myasthenic syndrome in Israel: Genetic and clinical characterization.

The objective of the study was to evaluate the epidemiology of patients with congenital myasthenic syndrome (CMS) in Israel. Targeted mutation analysis was performed based on the clinical symptoms and electrophysiological findings for known CMS. Additional specific tests were performed in patients of Iranian and/or Iraqi Jewish origin. All medical records were reviewed and clinical data, genetic mutations and outcomes were recorded. Forty-five patients with genetic mutations in known CMS genes from 35 families were identified. Mutations in RAPSN were identified in 13 kinships in Israel. The most common mutation was c.-38A>G detected in 8 patients of Iranian and/or Iraqi Jewish origin. Four different recessive mutations in COLQ were identified in 11 kinships, 10 of which were of Muslim-Arab descent. Mutations in CHRNE were identified in 7 kinships. Less commonly detected mutations were in CHRND, CHAT, GFPT1 and DOK7. In conclusion, mutations in RAPSN and COLQ are the most common causes of CMS in our cohort. Specific mutations in COLQ, RAPSN, and CHRNE occur in specific ethnic populations and should be taken into account when the diagnosis of a CMS is suspected.

CD59 deficiency is associated with chronic hemolysis and childhood relapsing immune-mediated polyneuropathy.

CD59 deficiency is a common finding in RBCs and WBCs in patients with chronic hemolysis suffering from paroxysmal nocturnal hemoglobinuria in which the acquired mutation in the PIGA gene leads to membrane loss of glycosylphosphatidylinositol-anchored membrane proteins, including CD59. The objective of the present study was to elucidate the molecular basis of childhood familial chronic Coombs-negative hemolysis and relapsing polyneuropathy presenting as chronic inflammatory demyelinating polyradiculoneuropathy in infants of North-African Jewish origin from 4 unrelated families. A founder mutation was searched for using homozygosity mapping followed by exome sequencing. The expression of CD59, CD55, and CD14 was examined in blood cells by flow cytometry followed by Western blot of the CD59 protein. A homozygous missense mutation, p.Cys89Tyr in CD59, was identified in all patients. The mutation segregated with the disease in the families and had a carrier rate of 1:66 among Jewish subjects of North-African origin. The mutated protein was present in the patients' cells in reduced amounts and was undetectable on the membrane surface. Based on the results of the present study, we conclude that the Cys89Tyr mutation in CD59 is associated with a failure of proper localization of the CD59 protein in the cell surface. This mutation is manifested clinically in infancy by chronic hemolysis and relapsing peripheral demyelinating disease.

Childhood acute and chronic immune-mediated polyradiculoneuropathies.

Immune-mediated polyradiculoneuropathies are divided into Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). In children subacute inflammatory demyelinating polyradiculoneuropathy is included in CIDP. Immune polyradiculoneuropathies are not exclusively demyelinating, and axonal forms also responding favourably to immunotherapy occur. Evidence-based data on efficacy of therapy in children is lacking, relying on retrospective data, open label studies on small numbers of children, and mainly adult derived data. Immunotherapy (intravenous human immunoglobulin [IVIg] and plasmapheresis) shortens GBS recovery time with most children recovering completely. Childhood CIDP usually responds to corticosteroids and slow tapering is required to prevent relapses. IVIg and plasmapheresis are also effective. CIDP children resistant to steroids, IVIg, and steroid-dependent patients present a therapeutic challenge. Immunosuppressive agents including methotrexate, azathioprine and cyclosporine are helpful in some cases. Anecdotal reports of treatment with interferons alpha or beta and monoclonal antibodies against specific B-cell antigens (Rituximab, Alemtuzumab) have been described in limited case reports. Childhood CIDP prognosis is mostly favourable. However, a proportion of cases have residual neurological deficit.

Electromyography (EMG) accuracy compared to muscle biopsy in childhood.

Reports show wide variability of electromyography (EMG) in detecting pediatric neuromuscular disorders. The study's aim was to determine EMG/nerve conduction study accuracy compared to muscle biopsy and final clinical diagnosis, and sensitivity for myopathic motor unit potential detection in childhood. Of 550 EMG/nerve conduction studies performed by the same examiner from a pediatric neuromuscular service, 27 children (ages 6 days to 16 years [10 boys; M:F, 1:1.7]) with muscle biopsies and final clinical diagnoses were compared retrospectively. Final clinical diagnoses were congenital myopathies (5 of 27,18%), nonspecific myopathies (biopsy myopathic, final diagnosis uncertain; 6 of 27, 22%), congenital myasthenic syndrome (3 of 27, 11%), juvenile myasthenia gravis (1 of 27, 4%), arthrogryposis multiplex congenita (2 of 27, 7%), hereditary motor and sensory neuropathy (1 of 27, 4%), bilateral peroneal neuropathies (1 of 27, 4%), and normal (8 of 27, 30%). There were no muscular dystrophy or spinal muscular atrophy patients. EMG/nerve conduction studies had a 74% agreement with final clinical diagnoses and 100% agreement in neurogenic, neuromuscular junction, and normal categories. Muscle biopsies concurred with final diagnoses in 87%, and 100% in myopathic and normal categories. In congenital myasthenic syndrome, muscle biopsies showed mild variation in fiber size in 2 of 3 children and were normal in 1 of 3. EMG sensitivity for detecting myopathic motor unit potentials in myopathies was 4 of 11 (36%), greater over 2 years of age (3 of 4, 75%), compared to infants less than 2 years (1 of 7, 14%), not statistically significant (P = .0879). EMGs false-negative for myopathy in infants < 2 years of age were frequently neurogenic (3 of 6, 50%). In congenital myopathies EMG detected myopathic motor unit potentials in 40%, with false-negative results neurogenic (20%) or normal (40%). Because our study has no additional tests for active myopathies, for example Duchenne muscular dystrophy genetic testing, our sensitivity for myopathies is lower than if we used a more global view. In conclusion, EMG detection rate of myopathic motor unit potentials at a young age was low, improving in children over 2 years of age. In neurogenic and neuromuscular junction disorders, the EMG has a very high detection rate. In children with mild to moderate neurogenic EMG findings and normal nerve conduction, a myopathy should always be considered.

Hereditary hypotonia, muscle weakness, failure to thrive, and cognitive delay in a large moslem kindred.

Five infants of a Moslem-Arab extended family were evaluated for common and characteristic clinical findings of failure to thrive, extreme muscle weakness, severe motor delay, and moderate to severe cognitive and verbal delay. All children were below the third percentile in weight and height, and three of them had head circumference below the third percentile. Neurologic examination revealed severe hypotonia, muscle weakness, and absent deep tendon reflexes. Two children died at 2 years of age, and none of the children acquired full head control and the motor milestones of rolling and sitting. Laboratory evaluation including muscle biopsies, genetic studies, and metabolic evaluation was nondiagnostic.

A test for the evaluation of the lateral cutaneous branch of the iliohypogastric nerve using somatosensory evoked potentials.

Iliohypogastric nerve (IHN) lesions are rare and usually due to abdominal surgery or trauma. There is no established electrophysiologic test for evaluating this nerve. A method is proposed to evaluate the IHN lateral cutaneous branch using somatosensory evoked potentials (SSEP). SSEP were elicited in 20 subjects using electrical stimulation from the greater trochanter up to 7 cm posterior to a point on the posterior axillary line, at the level of the greater trochanter. The active recording electrodes were placed 2 cm behind the Cz electrode in the midline, and the reference electrode midway between the Fpz and Fz electrodes in the midline. Stable responses were elicited in 19/20 subjects (12 male), aged 19-52 years (mean 32+/-6.6). Average positive peak onset latency was 32.5+/-3.7 msec, average amplitude 0.96+/-0.4 microV. Side-to-side latency difference range was 0-3.7 msec and amplitude difference range 0.06-1.04 microV. The technique proved sensitive in two cases with IHN injury following trauma, a 24-year-old male with a large hematoma over the right hip from the iliac crest to the greater trochanter tested twice one year apart, with stable repeat responses, and a 26-year-old female who sustained a crush injury to the right lateral pelvis. A side-to-side latency difference >3.7 msec or a unilateral absent response should be regarded as abnormal. This test may be useful for confirming the clinical picture of IHN lateral cutaneous branch lesions.