Myelin Sheath Of Peripheral Nerves Research Articles

CLINICAL-EXPERIMENTAL JUSTIFICATION OF PATHOGENETIC TREATMENT OF DIABETIC DAMAGE OF THE PERIPHERAL NERVOUS SYSTEM

Background. Diabetes mellitus is a chronic endocrinological disease that, in addition to the somatic sphere, affects all departments and levels of the nervous system. At the same time, its prevalence is increasing every year. Most often, neurological manifestations concern the peripheral nervous system in the form of sensory-motor polyneuropathies. Aim: To clinically and experimentally study the effectiveness of the complex scheme of prevention and treatment of diabetic polyneuropathy, which is composed taking into account the pathogenetic mechanisms of the studied pathology. To find out the clinical features of the course of the disease and electrophysiological patterns. Under experimental conditions, to study the dynamics of changes in the indicators of sensitivity (nociception) and motor function of peripheral nerves in case of diabetic nerve damage. Materials and methods. In the work, streptozotocin-induced diabetic polyneuropathy was reproduced in rats in a chronic experiment. The formation of the latter was confirmed by a morphological study of the sciatic and tail nerves with the determination of edema and degeneration of Schwann cells, as well as segmental demyelination and spasm of precapillary arterioles. Nicergoline, alpha-lipoic acid, group B vitamins, NG-nitro-L-arginine were used for therapeutic or preventive purposes in groups of animals. The speed of conduction of excitation along the tail nerve was studied. In addition, the "hot plate" test was used. In the clinical part of the work, 43 patients with diabetic polyneuropathy were examined. In addition to the clinical and neurological examination; assessed the severity of polyneuropathies according to the scale of neuropathy symptoms, as well as stimulation electroneuromyography.The patients were divided into groups: the first received a developed treatment complex, the second received conventional treatment. Results. The obtained data indicate the feasibility of using direct (NG-nitro-L-arginine) and indirect (nicergoline - "Sermion" and LC - "Alpha-lipon") inhibitors of nitric oxide synthesis, as well as the complex of vitamin preparations "Neovitam", taking into account their reparative and antioxidant properties, in the clinic in patients with diabetic polyneuropathy with a therapeutic, and possibly preventive purpose. The positive experimental and clinical effects of the developed DPP prevention and treatment scheme are associated with the development of antioxidant and reparative effects, as well as the restoration of the myelin sheath of peripheral nerves, since demyelination contributes to the development of the clinic of polyneuropathy. Conclusion. Patients with diabetic polyneuropathy who received a complex treatment scheme achieved probable clinical, neurological and neurophysiological improvement. On the basis of experimental research, the probable mechanisms of this kind of improvement due to the restoration of myelin, blood circulation, antioxidant and reparative effects have been proven.

Effects of Nutraceutical Compositions Containing Rhizoma Gastrodiae or Lipoic Acid in an In Vitro Induced Neuropathic Pain Model.

Peripheral neuropathy is caused by a malfunction in the axons and myelin sheaths of peripheral nerves and motor and sensory neurons. In this context, nonpharmacological treatments with antioxidant potential have attracted much attention due to the issues that some conventional pharmaceutical therapy can generate. Most of these treatments contain lipoic acid, but issues have emerged regarding its use. Considering this, the present study evaluated the beneficial effects of nutraceuticals based on Gastrodiae elata dry extract 10:1 or lipoic acid in combination with other substances (such as citicholine, B vitamins, and acetyl L-carnitine). To assess the combination's absorption and biodistribution and exclude cytotoxicity, its bioavailability was first examined in a 3D intestinal barrier model that replicated oral ingestion. Subsequently, a 3D model of nerve tissue was constructed to investigate the impacts of the new combination on the significant pathways dysregulated in peripheral neuropathy. Our findings show that the novel combination outperformed in initial pain relief response and in recovering the mechanism of nerve healing following Schwann cell injury by successfully crossing the gut barrier and reaching the target site. This article describes a potential alternative nutraceutical approach supporting the effectiveness of combinations with Gastrodiae elata extract in decreasing neuropathy and regulating pain pathways.

A new mutation in the TYMP-gene: clinical and morphological characteristics of a patient with MNGIE syndrome

Mitochondrial neurogastrointestinal encephalomyopathy is an extremely rare (1–9:1 000 000, Orphanet, 2021) multisystem genetic disease caused by mutations in the TYMP gene encoding the enzyme thymidine phosphorylase.The article presents the data of a thirteen‑year survey on 40‑year‑old patient D. with clinical manifestations of mitochondrial neurogastrointestinal encephalomyopathy syndrome associated with the previously undescribed missense mutation c.1301G>T (p.Gly434Val) of the TYMP gene. Detailed clinical picture (gastrointestinal dysfunction, cachexia, blepharoptosis, ophthalmoparesis, peripheral polyneuropathy and leukoaraiosis), electroneuromyography data (demyelination with secondary axonopathy), high blood serum level of dihydrothymine together with normal levels of thymidine and deoxyuridine made it possible to verify the diagnosis. Histopathological examination revealed atrophy of the longitudinal (outer) muscle layer of the small and large intestines and a significant decrease in the number of CD117+ cells (telocytes), signs of damage to the striated skeletal muscles of a mixed nature with a predominance of the myogenic pattern, as well the destruction of the myelin sheaths of peripheral nerves. Histochemical examination did not reveal “ragged red fibers” characteristic of mitochondrial pathology. Transmission electron microscopy demonstrated the presence of megalomitochondria in the myocardium.

Structural Abnormalities of the Optic Nerve and Retina in Huntington's Disease Pre-Clinical and Clinical Settings.

Huntington’s disease (HD) is a fatal neurodegenerative disorder caused by a polyglutamine expansion in the huntingtin protein. HD-related pathological remodelling has been reported in HD mouse models and HD carriers. In this study, we studied structural abnormalities in the optic nerve by employing Spectral Domain Optical Coherence Tomography (SD-OCT) in pre-symptomatic HD carriers of Caucasian origin. Transmission Electron Microscopy (TEM) was used to investigate ultrastructural changes in the optic nerve of the well-established R6/2 mouse model at the symptomatic stage of the disease. We found that pre-symptomatic HD carriers displayed a significant reduction in the retinal nerve fibre layer (RNFL) thickness, including specific quadrants: superior, inferior and temporal, but not nasal. There were no other significant irregularities in the GCC layer, at the macula level and in the optic disc morphology. The ultrastructural analysis of the optic nerve in R6/2 mice revealed a significant thinning of the myelin sheaths, with a lamellar separation of the myelin, and a presence of myelonoid bodies. We also found a significant reduction in the thickness of myelin sheaths in peripheral nerves within the choroids area. Those ultrastructural abnormalities were also observed in HD photoreceptor cells that contained severely damaged membrane disks, with evident vacuolisation and swelling. Moreover, the outer segment of retinal layers showed a progressive disintegration. Our study explored structural changes of the optic nerve in pre- and clinical settings and opens new avenues for the potential development of biomarkers that would be of great interest in HD gene therapies.

The coincidence of Guillain‐Barré syndrome and myasthenia gravis

Background The occurrence of both Guillain-Barré syndrome (GBS) and Myasthenia Gravis (MG) conditions in the same individual is rare. The underlying pathophysiology was assumed to be an autoimmune humoral mechanism. A molecular mimicry in which a cross-reaction between autoantibodies and myelin sheath of peripheral nerves and acetylcholine receptors of the neuromuscular junction (NMJ) cannot be excluded as an underlying cause. Case presentation An 18-year-old female patient was examined. She was presented with symptoms of generalized weakness and distal weakness in both upper and lower extremities, more pronounced on the right side and with associated right foot drop and bilateral ptosis. The electrophysiological study was performed and the AChR antibody titre was determined. The patient was diagnosed with GBS and MG. Conclusions In conclusion, GBS and MG are two different neurological entities with different pathophysiology. New onset or persistence of symptoms in a patient with GBS treated with IVIG or plasmapheresis should probe for another autoimmune neurological illness, preferably autoimmune neuromuscular disorders like MG.

Astragaloside IV alleviates Schwann cell injury in diabetic peripheral neuropathy by regulating microRNA-155-mediated autophagy

BackgroundMicroRNA-155(miR-155) is closely associated with diabetic peripheral neuropathy (DPN). Astragaloside IV (AST) is a significant extract of Astragalus membranaceus, which has been found to be effective in the treatment of DPN. However, whether astragaloside IV alleviate DPN via regulating miR-155-mediated autophagy remains unclear. PurposeThis study was designed to evaluate the effects of AST on DPN myelin Schwann cells injury and explore the mechanism of AST in treating DPN for the first time. MethodsGK rats fed with high-fat diet and RSC96 cells cultured in high glucose were used to establish DPN Schwann cells injury in vivo and in vitro model. The effects of AST on DPN were explored through blood glucose detection, nerve function detection, pathological detection and the expression of Neuritin detected by immunohistochemical. To study the effect of AST on the DPN Schwann cells autophagy and the upstream PI3K/Akt/mTOR pathway, the expressions of beclin-1 and LC3 were detected by western blot (WB) in sciatic nerves and by immunofluorescence (IFC) in RSC96 cells. The real-time polymerase chain reaction (RT-PCR) was applied to detect the expressions of miR-155, ATG5, ATG12 both in vivo and in vitro. The binding effect of miR-155 and target gene PI3KCA was verified by luciferase reporter gene assay. The expressions of PI3K, p-Akt/Akt, p-mTOR/mTOR were detected by WB and the expressions of PI3KCA were detected by RT-PCR in vitro. The apoptosis was detected by flow cytometry. Meanwhile, the influence of miR-155 overexpression and knocked down on the above indicators was also detected in RSC96 cells. At last, further mechanism experiments were conducted to verify the mechanism of AST regulating the autophagy and apoptosis of RSC96 cells. ResultsAST reduced blood glucose levels, alleviated peripheral nerve myelin sheath injury, and improved neurological function in DPN rats. In addition, AST enhanced the autophagy activity and alleviated the apoptosis in RSC96 cell. Mechanism study shown that AST promote autophagy via regulating miR-155-mediated PI3K/Akt/mTOR signaling pathways. AST reduced RSC96 cells apoptosis by promoting autophagy. ConclusionAST alleviate the myelin sheath injury of DPN caused by the apoptosis of Schwann cells via enhancing autophagy, which was attributed to inhibiting the activation of the PI3K/Akt/mTOR signaling pathway by upregulating miR-155 expression.

Brainstem intraparenchymal schwannoma with genetic analysis: a case report and literature review

BackgroundSchwannomas are neoplasms that typically arise from the myelin sheath of peripheral nerves and rarely originate within the brain parenchyma. Some case reports present schwannomas arising from the brainstem, but regrowth of the tumor and the efficacy of postoperative irradiation have not been examined. In addition, the genetic background of schwannomas arising from the brainstem has not been investigated.Case presentationA 21-year-old male presented with diplopia, dysphagia, and left-sided hemiparesis, dysesthesia, and ataxia. Intracranial imaging showed a heterogeneous mass with a cystic lesion in the pontomedullary junction. Since the tumor caused obstructive hydrocephalus, the patient underwent subtotal tumor resection. A histopathologic evaluation aided a diagnosis of brainstem intraparenchymal schwannoma. Gradual postoperative mass regrowth was recognized. Three-dimensional conformal radiotherapy was performed on the residual mass and surgical cavity. No tumor regrowth was observed 4 years after surgery. To investigate the genetic background of the tumor, target sequences for 36 genes, including NF2, SMARCB1, and LZTR1, and microsatellite analysis for loss of 22q did not show any somatic variants or 22q loss.ConclusionsWe suggest that brainstem schwannomas might differ from conventional schwannomas in their genetic background.

The prion protein is not required for peripheral nerve de- and remyelination after crush injury.

The cellular prion protein (PrP) is essential to the long-term maintenance of myelin sheaths in peripheral nerves. PrP activates the adhesion G-protein coupled receptor Adgrg6 on Schwann cells and initiates a pro-myelination cascade of molecular signals. Because Adgrg6 is crucial for peripheral myelin development and regeneration after nerve injury, we investigated the role of PrP in peripheral nerve repair. We performed experimental sciatic nerve crush injuries in co-isogenic wild-type and PrP-deficient mice, and examined peripheral nerve repair processes. Generation of repair Schwann cells, macrophage recruitment and remyelination were similar in PrP-deficient and wild-type mice. We conclude that PrP is dispensable for sciatic nerve de- and remyelination after crush injury. Adgrg6 may sustain its function in peripheral nerve repair independently of its activation by PrP.

Nerve Conduction Velocity in Smokers and Gutka Chewers: A Case-control Study

Introduction: Chemicals that are present in cigarette/bidi smoke and gutka have been known to cause subclinical changes in myelin sheaths of peripheral nerves. Despite the antiquity and popularity of smoking and gutka chewing, its effect has not been investigated systematically in young adults. Aim: To investigate the chronic effects of smoking and gutka chewing on Nerve Conduction Velocity (NCV). Materials and Methods: The case-control study was conducted in the Department of Physiology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India, from November 2018 to December 2020. A 40 male smokers (age group 20-60 years), 40 gutka chewers (age group 20-60 years) along with 40 age matched healthy male controls. The nerve conduction study was performed by using fully computerised Electromyography (EMG) and NCV machine. Sensory Nerve Conduction Velocity (SNCV) and Motor Nerve Conduction Velocity (MNCV) test of median and ulnar nerves was performed on subjects. Data was analysed by using unpaired t-test. Results: In this study of comparative analysis of total 120 subjects, [40 controls and 80 cases (40 cases of smokers and tobacco chewers each)], statistically significant changes (p-value <0.05) were found in the sensory NCV of both the nerves and motor NCV of median nerve in smokers whereas no such changes were found in motor NCV of both nerves in gutka chewers. Conclusion: It can be concluded that smoking causes more reduction in NCV than gutka chewing.

Aberrant Splicing in GJB1 and the Relevance of 5' UTR in CMTX1 Pathogenesis.

The second most common form of Charcot-Marie-Tooth disease (CMT) follows an X-linked dominant inheritance pattern (CMTX1), referring to mutations in the gap junction protein beta 1 gene (GJB1) that affect connexin 32 protein (Cx32) and its ability to form gap junctions in the myelin sheath of peripheral nerves. Despite the advances of next-generation sequencing (NGS), attention has only recently also focused on noncoding regions. We describe two unrelated families with a c.-17+1G>T transversion in the 5′ untranslated region (UTR) of GJB1 that cosegregates with typical features of CMTX1. As suggested by in silico analysis, the mutation affects the regulatory sequence that controls the proper splicing of the intron in the corresponding mRNA. The retention of the intron is also associated with reduced levels of the transcript and the loss of immunofluorescent staining for Cx32 in the nerve biopsy, thus supporting the hypothesis of mRNA instability as a pathogenic mechanism in these families. Therefore, our report corroborates the role of 5′ UTR of GJB1 in the pathogenesis of CMTX1 and emphasizes the need to include this region in routine GJB1 screening, as well as in NGS panels.

A Case Report: Rare Presentation of Intracranial Hemorrhage post Guillain Barré Syndrome

Background: Guillain Barre Syndrome (GBS) is an autoimmune disease where antibodies attack the myelin sheath of peripheral nerves. The hallmark of the disease includes symmetrical quadriparesis, respiratory distress, and failure with subsequent need for mechanical ventilation. Most cases occur after a viral or bacterial infection. Other causes, such as intracranial hemorrhage, also exist, and several case studies report an association between these two pathologies. Case Report: In this report, we present the case of an elderly male patient with intracranial (IC) bleeding post-GBS. The patient was admitted to the hospital for dyspnea and diagnosed with pneumonia. When he started complaining of progressive bilateral ascending paralysis of his lower extremities, we performed a lumbar puncture, and he was diagnosed with GBS. We started him on intravenous immune globulins (IVIGs) immediately, but his weakness progressed to include his respiratory muscles, and he required mechanical ventilatory support with Intensive Care Unit (ICU) admission. We extubated him after two weeks, but he needed to be reintubated 24 hours later for a severely decreased level of consciousness. An urgent computed tomography scan of the brain showed IC bleeding. The patient developed a septic shock due to his pneumonia, which was refractory to antibiotics and vasopressors. He passed away a few weeks after that. Conclusion: Our case represents a unique type of association between IC hemorrhages and GBS, where the bleeding occurred several days after, as opposed to before GBS. It also reinforces the correlation between GBS and Intracranial bleeding and stresses the importance of having a high index of suspicion when facing either pathology since both have similar symptoms that may overlap or mask each other.

Unusual electrophysiological findings in a Chinese ALS 4 family with SETX-L389S mutation: a three-year follow-up.

Amyotrophic lateral sclerosis type 4 (ALS4) is a familial form of ALS caused by mutations in the SETX gene. To date, there are seven unrelated ALS4 families with four missense mutations (L389S, T31I, R2136H, and M386T) in SETX. ALS4 is characterized by early onset, distal muscle weakness and atrophy, pyramidal signs, and the absence of sensory deficits. Motor conduction studies often present normality or reduced amplitudes of compound muscle action potential (CMAP). The conduction blocks (CBs) are rare and only observed in one male of an Italian ALS4 family. Our study showed that seven symptomatic patients presented the classical ALS4 phenotype with two asymptomatic females in a Chinese family spanning three generations. Sequencing analysis revealed a heterozygous c.1166T > C/p.L389S mutation in SETX that co-segregated with disease phenotype in the family. The same mutation has been identified previously in three ALS4 families from the United States and Italy, respectively. Specifically, three young males presented multiple CBs and abnormal temporal dispersions (TD) in the median, ulnar and tibial nerves over the three-year follow-up period. Moreover, for the first time, we found that senataxin was also expressed in the myelin sheath of peripheral nerves besides axons. The study indicates that CBs and abnormal TD are the characteristics in the ALS4 family, providing pivotal familial evidence of CBs and TD of motor nerves in ALS4. The unusual electrophysiological features may be associated with the expression of senataxin in peripheral nerves.

Cryo-EM, X-ray diffraction, and atomistic simulations reveal determinants for the formation of a supramolecular myelin-like proteolipid lattice

Myelin protein P2 is a peripheral membrane protein of the fatty acid-binding protein family that functions in the formation and maintenance of the peripheral nerve myelin sheath. Several P2 gene mutations cause human Charcot-Marie-Tooth neuropathy, but the mature myelin sheath assembly mechanism is unclear. Here, cryo-EM of myelin-like proteolipid multilayers revealed an ordered three-dimensional (3D) lattice of P2 molecules between stacked lipid bilayers, visualizing supramolecular assembly at the myelin major dense line. The data disclosed that a single P2 layer is inserted between two bilayers in a tight intermembrane space of ∼3 nm, implying direct interactions between P2 and two membrane surfaces. X-ray diffraction from P2-stacked bicelle multilayers revealed lateral protein organization, and surface mutagenesis of P2 coupled with structure-function experiments revealed a role for both the portal region of P2 and its opposite face in membrane interactions. Atomistic molecular dynamics simulations of P2 on model membrane surfaces suggested that Arg-88 is critical for P2-membrane interactions, in addition to the helical lid domain. Negatively charged lipid headgroups stably anchored P2 on the myelin-like bilayer surface. Membrane binding may be accompanied by opening of the P2 β-barrel structure and ligand exchange with the apposing bilayer. Our results provide an unprecedented view into an ordered, multilayered biomolecular membrane system induced by the presence of a peripheral membrane protein from human myelin. This is an important step toward deciphering the 3D assembly of a mature myelin sheath at the molecular level.

Malignant peripheral nerve sheath tumor - a case report and review

This case report aims to contribute to the understanding and to present a new look on the treatment of a rare, aggressive and poorly understood pathology, known as malignant tumor of the peripheral nerve myelin sheath. The objective of this research is to help building a better understanding of this pathology and to evaluate what is new in diagnosis and treatment. We used PubMed’s articles with the descriptors: malignant peripheral nerve sheath tumor, Ki67, and malignant tumor immunohistochemistry of the peripheral nerve sheath. 17 articles were selected. We also used the descriptor “sarcoma staging” for the visualization of a book chapter and a journal. Malignant neoplasm of the peripheral nerve myelin sheath is a disease that mainly affects neurofibromatosis-1 or patients with prior radiotherapy, but may occur randomly, as with the patient in question. Due to illness multiple incidence locations, the symptoms may be late and staging is difficult. The staging is performed taking into account the size of the primary tumor, its location, lymph node involvement, presence of distant metastases and degree of cell differentiation. The diagnosis is made after resection of the piece with anatomopathological and immunohistochemical analysis, which may delay the treatment. Therefore, it has been seen that the most common treatment continues to be complete surgery with free margins, but there are promising studies in the genetics field for the treatment and better understanding of this pathology

Breast schwannoma – a rare entity

Introduction: Schwannoma is a benign tumor originating from Schwann cells present in the myelin sheath of peripheral nerves. Breast presentation is rare, and its clinical manifestation can mimic that of breast carcinoma. Objectives: To report the case of a patient with breast Schwannoma. Method/Case report: T.S.L., 14 years old, presented a nodule in the left breast (LB) with local growth for 2 months. Ultrasound (US) revealed a cystic formation in the lower outer quadrant of 1.8x1.3 cm, BI-RADS 2. Physical examination indicated a nodular skin lesion next to the LB fold, with 2 cm at 5 h, 7 cm from the nipple. After the surgical excision of the nodule, anatomopathological examination showed a spindle cell neoplasm without nodular-pattern atypia or malignancy characteristics. Immunohistochemistry (IHC) confirmed the Schwannoma diagnosis. Considering this scenario, annual control was started, and the patient has no evidence of the disease after 5 years of diagnosis. Results/Discussion: Schwannoma is a typically benign tumor originating from Schwann cells in the myelin sheath of the nerves. It may result from the parasympathetic or sympathetic division of the autonomic nervous system of the organ. It is one of the few truly encapsulated tumors of the human body and almost always solitary. It is usually located in the trunk, flexor surfaces, retroperitoneum, and rarely in the breast, representing approximately 2.6% of Schwannoma cases. It affects individuals aged 30 to 50 years, with equal incidence in both men and women. The skin lesion presents as a sessile, asymptomatic nodule of 1–3 cm and slow growth. Pain and sensitivity may be present when tumor growth causes nerve compression. Mammography (MMG) shows well-circumscribed opacity, with a density similar to that of soft tissue. US usually reveals well-defined, hypoechoic, solid lesions and can include the target sign, posterior acoustic enhancement, and continuity with peripheral nerves. The definitive diagnosis is made histologically, and the differential diagnosis involves other spindle cell neoplasms, such as fibroadenoma, phyllodes tumor, leiomyoma, fibromatosis, and, rarely, metaplastic carcinoma. Fine-needle aspiration biopsy (FNAB) showed palisading fibrillar cells with non-atypical spindle-shaped nuclei forming Verocay bodies. IHC indicates intense and uniform expression of S-100 protein. Malignant transformation occurs in 3–10% of cases, with high cellular proliferation, atypical mitotic activity, cellular and nuclear pleomorphism, and foci of necrosis. The treatment of choice is surgical excision of the lesion. Tumor recurrence is low and associated with the mitotic index. Conclusion: The case reported and publications found bring to light the discussion on diagnosis and treatment of breast Schwannoma, a rare and benign neoplasm in this location.

Schwann cells and trigeminal neuralgia.

Schwann cells are components of the peripheral nerve myelin sheath, which supports and nourishes axons. Upon injury of the trigeminal nerve, Schwann cells are activated and cause trigeminal neuralgia by engulfing the myelin sheath and secreting various neurotrophic factors. Further, Schwann cells can repair the damaged nerve and thus alleviate trigeminal neuralgia. Here, we briefly describe the development and activation of Schwann cells after nerve injury. Moreover, we expound on the occurrence, regulation, and treatment of trigeminal neuralgia; further, we point out the current research deficiencies and future research directions.

Occurrence of Guillain-Barr\xe9 syndrome and Myasthenia Gravis in an elderly male

IntroductionThe occurrence of both Guillain-Barré syndrome(GBS) and myasthenia gravis (MG) in the same individual is rare. The underlying pathophysiology was assumed to be autoimmune humoral mechanisms and molecular mimicry with a cross-reaction between autoantibodies and myelin sheath of peripheral nerves and acetylcholine receptors of the neuromuscular junction (NMJ).Case descriptionA 68-year-old male known diabetic and hypertensive with good drug compliance presented with acute onset quadriparesis with bulbar involvement for 1 day. On examination, he had mild neck flexion weakness and bulbar weakness. He had flaccid quadriparesis with absent deep tendon reflexes and negative Babinski. The rest of the neurological examination was normal.Discussion and evaluationBlood and electrophysiological studies showed evidence of demyelinating polyradiculoneuropathy with temporal dispersion suggestive of Guillain-Barré syndrome. He was treated with intravenous immunoglobin and complete resolution of symptoms. Two months later, he presented with new-onset asymmetrical ptosis and bulbar symptoms for 3 days. On further evaluation, repetitive nerve stimulation showed postsynaptic neuromuscular disorder pattern typical of myasthenia gravis, which was further confirmed by positive acetylcholinesterase receptor antibodies (AChR). Thymoma was ruled out by imaging. He was treated with anticholinesterases, low dose steroids, and immunosuppressants (azathioprine) following which he had improvement of symptoms.ConclusionOur patient, who was initially diagnosed with Guillain-Barré syndrome and recovered, presented 2 months later with a new-onset illness suggestive of myasthenia gravis. This existence of two different neurological entities in the same individual is a rarity, and early recognition is essential for treatment decision and prognostic strategies.

Schwannoma of the Common Peroneal Nerve – A Rare Incidence

Schwannomas are benign tumours arising from neurilemmal cells which forms the myelin sheath of peripheral nerves. It usually occurs in the head, but may be found in the brachial plexus and sciatic nerve. Common peroneal nerve schwannoma are rare. We report a case of a middle age gentleman who presented with pain and swelling over the right popliteal fossa with associated right radicular pain of the anterolateral leg and weakness of ankle dorsiflexion. Examination revealed a 3x2 cm lump behind the posterolateral aspect of the right knee with positiveTinel’s sign upon tapping of the lump, sensory deficit over the anterolateral aspect of the leg and the ankle dorsiflexors had a muscle power of grade 3. Magnetic resonance imaging (MRI) of the right leg revealed a well circumscribed, oval lesion located along the pathway of the common peroneal nerve homogenously hypointense on T1-weighted images and heterogeneously hyperintense on T2 weighted images compared to the muscles. The lesion was not surpressed on fat suppression sequences. Intra-operatively, we noted that the schwannoma was in continuity with the common peroneal nerve. The patient underwent excision of the schwannoma. Post operatively, the pain reduced remarkably but patient suffers from numbness and right foot drop as a complication of the tumour. This case highlights the rarity of common peroneal nerve schwannoma which presents with neuropathic symptoms complicated with right foot drop.

Schwannoma of the hypoglossal nerve: Review of the literature based on an illustrative case

Schwannomas are benign tumours that originate from the myelin sheath of peripheral nerves. They are characterised by a slow growth tendency. Benign schwannomas represent 35% of the head and neck district tumours. Hypoglossal schwannomas account for 5% of non-vestibular schwannomas, and malignant schwannomas occur very rarely. In the present case report, the case of a 49-year-old man who presented with paraesthesias in the left parotid and submandibular region, associated with sensation of foreign bodies and dysphagia for solids, is described. A clinical examination revealed the presence of an ovoid palpable mass in the lateral-cervical region of the neck. The patient subsequently underwent excisional surgery, and neuropathological evaluation of the specimen confirmed the diagnosis of benign schwannoma with Antoni areas A and B. Despite the rarity of schwannomas, this condition should be considered in differential diagnoses for masses localised in the neck, as in cases where they reach considerable sizes (>3 cm in diameter). Surgery therefore represents the first-choice treatment.

Clinical and biophysical characterization of 19 GJB1 mutations.

ObjectiveCharcot–Marie–Tooth disease type X1 (CMTX1), which is caused by mutations in the gap junction (GJ) protein beta‐1 gene (GJB1), is the second most common form of Charcot–Marie–Tooth disease (CMT). GJB1 encodes the GJ beta‐1 protein (GJB1), which forms GJs within the myelin sheaths of peripheral nerves. The process by which GJB1 mutants cause neuropathy has not been fully elucidated. This study evaluated the biophysical characteristics of GJB1 mutants and their correlations with the clinical features of CMTX1 patients.MethodsAll patients with a validated GJB1 mutation were assessed using the Charcot–Marie–Tooth disease neuropathy score version 2 (CMTNS). The impacts of the mutations on the biophysical functions of GJB1 were characterized by assessing intracellular localization, expression patterns, and GJ Ca2+ permeability.ResultNineteen GJB1 mutations were identified in 24 patients with a clinical diagnosis of CMT. Six are novel mutations: p.L6S, p.I20F, p.I101Rfs*8, p.F153L, p.R215P, and p.D278V. Diverse pathological effects of the mutations were demonstrated, including reduced GJB1 expression, intracellular mislocalization, and altered GJ functions. GJB1 mutations that caused a complete loss of GJ Ca2+ permeability appeared to be associated with an earlier disease onset, whereas those resulting in preservation of GJ permeability and with predominant cell membrane expression tended to have a later onset and a milder phenotype.InterpretationThis study demonstrated that the degree of loss of GJ function caused by the GJB1 mutations might contribute to the onset and severity of neuropathic symptoms in CMTX1.