Erythromelalgia Research Articles

A FUNÇÃO DOS CANAIS DE SÓDIO NAV1.7 NA DOR NEUROPÁTICA: GENÉTICA, MECANISMOS MOLECULARES, BIOMARCADORES E PERSPECTIVAS TERAPÊUTICAS

The deepening understanding of the molecular mechanisms underlying neuropathic pain has highlighted the importance of the sodium channel Nav1.7, encoded by the SCN9A gene, as a critical element in regulating neuronal excitability and transmitting action potentials. Nav1.7 is found in nociceptive sensory neurons, playing a vital role in conducting pain signals in the peripheral nervous system. Its activity allows the depolarization of neuronal membranes in response to painful stimuli, facilitating the rapid influx of sodium ions into the cell and generating action potentials that are sent to the brain for pain perception. Mutations in the SCN9A gene are strongly linked to various neuropathic pain conditions. Mutations that increase Nav1.7 activity, such as the p.E1113K variant, intensify the excitability of sensory neurons, leading to conditions such as primary erythromelalgia. In contrast, mutations that reduce Nav1.7 functionality, such as p.I230T, result in lower neuronal excitability, culminating in congenital insensitivity to pain. Advances in neuroimaging and molecular genetics have been fundamental in identifying biomarkers of Nav1.7 dysfunctions. These methods allow the detection of changes in pain processing within the central nervous system, facilitating the identification of specific genetic mutations that contribute to neuropathic conditions. Advanced genetic techniques, such as exome and genome sequencing, enable detailed diagnoses and personalized therapeutic approaches. Promising therapies involve specific inhibitors for Nav1.7, aiming to reduce neuronal hyperexcitability. Additionally, gene therapies, including techniques such as CRISPR-Cas9, have been explored to correct mutations in the SCN9A gene. In conclusion, scientific progress allows for precise diagnoses and personalized treatments, promoting effective management of neuropathic pain.

Studying Erythromelalgia Using Doppler Flowmetry Perfusion Signals and Wavelet Analysis-An Exploratory Study.

Erythromelalgia (EM) is a rare disease, which is still poorly characterized. In the present paper, we compared the hand perfusion of one female EM patient, under challenges, with a healthy control group. Using a laser Doppler flowmeter (LDF) with an integrated thermal probe, measurements were taken in both hands at rest (Phase I) and after two separate challenges-post-occlusive hyperemia (PORH) in one arm (A) and reduction of skin temperature (cooling) with ice in one hand (B) (Phase II). The final measurement periods corresponded to recovery (Phases III and IV). The control group involved ten healthy women (27.3 ± 7.9 years old). A second set of measurements was taken in the EM patient one month after beginning a new therapeutic approach with beta-blockers (6.25 mg carvedilol twice daily). Z-scores of the patient's LDF and temperature fluctuations compared to the control group were assessed using the Wavelet transform (WT) analysis. Here, fluctuations with |Z| > 1.96 were considered significantly different from healthy values, whereas positive or negative Z values indicated higher or lower deviations from the control mean values. Cooling elicited more measurable changes in LDF and temperature fluctuations, especially in higher frequency components (cardiac, respiratory, and myogenic), whereas PORH notably evoked changes in lower frequency components (myogenic, autonomic, and endothelial). No significant Z-score deviations were observed in the second measurement, which might signify a stabilization of the patient's distal perfusion following the new therapeutic approach. This analysis involving one EM patient, while clearly exploratory, has shown significant deviations in WT-derived physiological components' values in comparison with the healthy group, confirming the interest in using cold temperature as a challenger. The apparent agreement achieved with the clinical evaluation opens the possibility of expanding this approach to other patients and pathologies in vascular medicine.

Erythromelalgia caused by the missense mutation p.Arg220Pro in an alternatively spliced exon of SCN9A (NaV1.7).

Erythromelalgia (EM), is a familial pain syndrome characterized by episodic 'burning' pain, warmth, and erythema. EM is caused by monoallelic variants in SCN9A, which encodes the voltage-gated sodium channel (NaV) NaV1.7. Over 25 different SCN9A mutations attributed to EM have been described to date, all identified in the SCN9A transcript utilizing exon 6N. Here we report a novel SCN9A missense variant identified in seven related individuals with stereotypic episodes of bilateral lower limb pain presenting in childhood. The variant, XM_011511617.3:c.659G>C;p.(Arg220Pro), resides in the exon 6A of SCN9A, an exon previously shown to be selectively incorporated by developmentally regulated alternative splicing. The mutation is located in the voltage-sensing S4 segment of domain I, which is important for regulating channel activation. Functional analysis showed the p.Arg220Pro mutation altered voltage-dependent activation and delayed channel inactivation, consistent with a NaV1.7 gain-of-function molecular phenotype. These results demonstrate that alternatively spliced isoforms of SCN9A should be included in all genomic testing of EM.

Clinical Challenges in Primary Erythromelalgia: a Real-Life Experience from a Single Center and a Diagnostic-Therapeutic Flow-Chart Proposal.

Primary erythromelalgia (EM) is a rare clinical syndrome characterized by recurrent erythema, burning pain and warmth of the extremities. The symptoms greatly compromise the patients' quality of life leading to severe disability. SCN9A mutations can be the cause of the disease. Dermatologists are often the specialists these patients turn to for assistance. To describe the demographic and clinical characteristics of patients with primary EM, to assess the presence and mutation types in the SCN9A gene, to evaluate the effectiveness of several therapeutic approaches, and to propose a diagnostic algorithm with therapeutic implications. A monocentric retrospective study using the database of patients with a discharge diagnosis of primary EM of our Center. Demographic, clinical, instrumental and laboratory data of patients were reviewed. Eleven female patients (age range 16 to 57) were selected. All patients were affected in both the lower and upper extremities. Follow-up ranged from 2 to 9 years. Four patients had four different heterozygous variants of the SCN9A gene. Two patients, although genetically negative, had a suggestive family history. A variety of medications were tried in all our patients to alleviate symptoms, but their efficacy was variable, partial and/or transitory. The most effective therapies were antihistamines, venlafaxine, and mexiletine. The diagnosis and treatment of EM remain challenging. Patients with this condition display a wide spectrum of clinical manifestations and severity, as well as a paucity of resources and structures to support them. Mutations in the SCN9A gene are not always detected.

Primary erythromelalgia mainly manifested by hypertensive crisis: A case report and literature review.

BackgroundPrimary erythrocytic (PEM) is a rare autosomal dominant single gene disease. Most of the changes of gene loci can be found by whole exon gene sequencing, and the clinical symptoms and patient survival can be improved by specific site-to-site drug treatment. The other manifestations of this patient population are not remarkable. After the application of common drugs, the toxicity and side effects can be limiting. In addition to other common clinical manifestations, we found that the only unique manifestation of this patient was hypertensive crisis. Following multidisciplinary diagnosis and treatment (MDT), we decided to first control hypertension to alleviate the acute and critical patients. However, after controlling the hypertensive crisis, we unexpectedly found that the clinical symptoms of the patients had been significantly improved. Therefore, we concluded that the use of antihypertensive drugs can treat erythematous limb pain with the clinical manifestation of hypertensive crisis. Here, we describe a typical PEM disease, primary clinical features, diagnosis and treatment.MethodsMedical records of an 8-year-old boy with PEM were analyzed retrospectively, which included clinical characteristics, follow-up information, and SCN9A (Sodium Voltage-Gated Channel Alpha Subunit 9) gene analysis.ResultsThe 8-year-old boy had complained of abnormal paresthesia in his feet and ankles with burning sensation and pain for 2 years. The skin of both lower legs was red and underwent ichthyosis and lichenification. Genetic analysis confirmed the existence of a SCN9A gene mutation. The symptoms were gradually improved by treating with intravenous drip and oral administration of nitroglycerin to slow his heart rhythm.ConclusionPrimary erythrocytic is characterized by skin ulceration, redness, elevated temperature, and severe burning pain primarily in both lower extremities. PEM can be diagnosed by genetic analysis. As this case demonstrates, treating with nitroglycerin as the drug of choice to control the hypertensive crisis significantly improved the symptoms of PEM and hypertension in this patient.

A stepwise approach for the management of primary erythromelalgia: A prospective single-arm study

A stepwise approach for the management of primary erythromelalgia: A prospective single-arm study

A reappraisal of the presence of small or large fiber neuropathy in patients with erythromelalgia

ObjectiveTo assess the contribution of large and small nerve fiber alteration in erythromelalgia (EM). MethodsThirty-three EM patients were included and underwent clinical evaluation based on EM severity score, DN4, and Utah Early Neuropathy Scale (UENS) score. Neurophysiological evaluation consisted in nerve conduction studies (NCS) for large nerve fibers and specific tests for small nerve fibers: electrochemical skin conductance, cold and warm detection thresholds, and laser evoked potentials. Finally, the evaluation of vascular changes was based on the presence of clinical feature of microvascular disorders and the measurement of the Toe Pressure Index (TPI). ResultsWhile 28 patients (85%) had vascular alteration on TPI or clinical features, 23 patients (70%) had small-fiber neuropathy on neurophysiological tests, and only 10 patients (30%) had large fiber neuropathy on NCS. Regarding clinical scores, there was no difference between groups (presence or absence of large- or small-fiber neuropathy or microvascular disorder) except for a higher UENS score in patients with large fiber neuropathy. ConclusionPeripheral neuropathy, mostly involving small nerve fibers, is almost as common as microvascular changes in EM, but remains inconstant and not related to a specific neuropathic pattern or higher clinical severity. SignificanceThe association of neuropathic and vascular factors is not systematic in EM, this syndrome being characterized by different pathophysiological mechanisms leading to a common clinical phenotype.

Assessing the impact of pain-linked Nav1.7 variants: An example of two variants with no biophysical effect

ABSTRACT Mutations in the voltage-gated sodium channel Nav1.7 are linked to human pain. The Nav1.7/N1245S variant was described before in several patients suffering from primary erythromelalgia and/or olfactory hypersensitivity. We have identified this variant in a pain patient and a patient suffering from severe and life-threatening orthostatic hypotension. In addition, we report a female patient suffering from muscle pain and carrying the Nav1.7/E1139K variant. We tested both Nav1.7 variants by whole-cell voltage-clamp recordings in HEK293 cells, revealing a slightly enhanced current density for the N1245S variant when co-expressed with the β1 subunit. This effect was counteracted by an enhanced slow inactivation. Both variants showed similar voltage dependence of activation and steady-state fast inactivation, as well as kinetics of fast inactivation, deactivation, and use-dependency compared to WT Nav1.7. Finally, homology modeling revealed that the N1245S substitution results in different intramolecular interaction partners. Taken together, these experiments do not point to a clear pathogenic effect of either the N1245S or E1139K variant and suggest they may not be solely responsible for the patients’ pain symptoms. As discussed previously for other variants, investigations in heterologous expression systems may not sufficiently mimic the pathophysiological situation in pain patients, and single nucleotide variants in other genes or modulatory proteins are necessary for these specific variants to show their effect. Our findings stress that biophysical investigations of ion channel mutations need to be evaluated with care and should preferably be supplemented with studies investigating the mutations in their context, ideally in human sensory neurons.

Erythromelalgie primitive, une nouvelle observation

Erythromelalgia is a vascular acrosyndrome first described by Mitchell in 1878. It is rare, affecting the feet more than the hands, and the symptoms are triggered by heat and calmed by cold. There are two types: the primary form (exceptional hereditary form and non-familial idiopathic form), the secondary form (associated with hematological disorders and systemic diseases). The exact mechanism is the subject of controversy. It has an important functional impact. We report a new observation. It was a 39-year-old woman, multiparous, in a polygamous marriage, residing in Gao, referred to the emergency room on February 12, 2018 for severe hand pain. She had presented with the same episode in March 2011 relieved by hand immersion in cold water associated with an unidentified analgesic. No similar conditions were found in her family. On examination, the general condition was good, we noted a large placard of both hands, red with a salmon appearance, taking the eminences in a V shape, sparing the back of the hands. The lesion was warm and painful to the touch, without any portal of entry (A, B, C). Blood count, sedimentation rate, blood glucose and antinuclear antibodies were normal. 500mg/day acetylsalicylic acid treatment was instituted. The evolution under this treatment was favorable with complete remission after two weeks (D). The diagnosis of primary idiopathic erythromelalgia was evoked in view of the patient's age, the clinical and biological signs and the response to treatment.

Novel treatment modality in a case of resistant erythromelalgia

<p>Erythromelalgia presents with redness, pain and warmth of the extremities, which is exacerbated by warming and relieved by cooling. Treatment of pain in erythromelalgia can be difficult, and often polypharmacy is utilized. No single therapy has been found to provide complete relief for any patient. Therefore, a multidisciplinary approach is required to treat pain and its significant negative impact across many domains of functioning. A 21 year old male diagnosed case of primary erythromelalgia since 5 years, presented multiple times with recurrent pain and erythema in bilateral lower limbs. Patient was treated initially with oral antibiotics, tramadol and prednisolone, without relief. Aspirin, amitriptyline, pregabalin, carbamazepine, atenolol were later added which gave him partial relief. Epidural caudal catheter with daily infusion of anesthesia was added along with topical buprenorphine patch when conservative polypharmacy failed to provide complete relief and later unilateral lumbar sympathectomy was done as a last resort. Adding pentoxifylline and compression therapy improved the patient’s condition drastically and complete remission is in progress. The patient required a multidisciplinary approach for pain management and surgical intervention was required due to his refractory nature. However, this also does not give complete relief and thus a combination of both medical and surgical methods is required for best control of symptoms.</p>

Primary Erythromelalgia Complicated by Cellulitis: A Case Report and Review of Literature

Erythromelalgia is a rare disease with increasing incidence. It manifests as episodic painful red extremities triggered by heat. External cooling provides temporary symptomatic relief but may lead to complications such as cellulitis. Management includes trigger control, behavioral therapy and pain management. A 47-year-old African American male presented to the hospital with worsening bilateral lower extremity pain for three months. It was episodic, triggered by running and associated with erythema and swelling. Patient used cold water immersion and air conditioning for pain relief. One week prior to presentation, he developed painful blisters on his feet. On presentation, vital signs were stable, patient was afebrile. Acute infection was ruled out and he was discharged with outpatient rheumatology follow up for erythromelalgia. He returned one week later with worsening symptoms. CT scan of lower extremities indicated bilateral cellulitis. Patient was managed by medicine, dermatology, rheumatology, and podiatry for cellulitis, fungal infection, trench foot and primary erythromelalgia with antibiotics, antifungals, gabapentinoids and behavioral therapy. His infection resolved and pain improved. He was discharged with outpatient rheumatology follow up. Erythromelalgia is a highly debilitating disease with episodes of burning erythematous extremities triggered by increase in skin temperature. Patients seek pain relief by excessive external cooling. Pathophysiology involves gain of function mutation in voltage gated sodium channels causing autoregulatory dysfunction of skin. Underlying disease mechanisms are ambiguous and may involve unidentified genetic components and unknown triggers. It is a clinical diagnosis. Therapy requires a multidisciplinary approach. Complications should be promptly addressed given attention next to symptomatic relief. There is a lack of disease specific treatment and complete remission is unlikely. Our patient responded well to gabapentinoids and behavioral therapy.

Vascular acrosyndromes in young adult population. Definition of clinical symptoms and connections to joint hypermobility.

Clinical recognition of vascular acrosyndromes is often challenging. The term Raynaud's phenomenon (RP) is commonly overused to describe any form of cold-related disorder. This study aims to formally evaluate peripheral vascular symptoms affecting the population, aged ≤ 40years, and identify any correlations to joint hypermobility (JH). Fifty patients (31 males, 19 females) with vasomotor symptoms enrolled in this five-year prospective observational study. Clinical examination by a rheumatologist and a vascular surgeon was performed along with cardiology, echocardiographic and Doppler evaluation. Patients underwent blood cell count, biochemistry, thyroid and selectively immunologic testing. Twenty-four (48%) of them performed nailfold capillaroscopy. The SPSS for Windows, v.17.0, Chicago, USA, was used for the statistical analyses. Twenty-eight patients (56%) presented with erythromelalgia (EM), 6 (12%) with acrocyanosis (AC) and 9 (18%) as a combination of the above disorder. RP diagnosed in five (10%) while two patients (4%) presented as a mix of EM-RP. There was no correlation with abnormal laboratory tests. Increased incidence of JH was found in EM and AC patients. Among those who were tested with nailfold capillaroscopy, 75% had abnormalities ranged from mild to autoimmune-like diseases. Erythromelalgia is the commonest functional vasculopathy in young population followed by acrocyanosis and a combination of these conditions. Joint hypermobility is markedly increased, indicating that dysautonomy may be considered the causative factor following a trigger event. Overall, RP was observed in 14% of patients. Clinical recognition of these disorders avoids unnecessary investigation. Key Points • Vascular acrosyndromes in young adults are commonly functional disorders resembling vascular algodystrophy induced by thermic stress. • Dysautonomy of joint hypermobility is the co-factor influencing the appearance of the vascular disorders. • Raynaud's phenomenon accounts to approximately 14% of vascular acrosyndromes presented in the young adult population.

Primary erythromelalgia – case report

Primary erythromelalgia – case report

Erythromelalgia and Peripheral Nerve Block: A Case Report

A 79-year-old woman with primary erythromelalgia underwent a left reverse total shoulder arthroplasty with a left interscalene nerve block, a superficial cervical plexus block, and a general endotracheal anesthetic, with no residual neurological deficits. Herein, we discuss the classification and pathophysiology of erythromelalgia along with the anesthetic considerations of peripheral nerve blockade in patients with primary erythromelalgia.

Review of primary and secondary erythromelalgia.

Erythromelalgia is a condition characterized by episodic pain, erythema and temperature of the extremities, which is relieved by cooling and aggravated by warming. It is useful to review this topic in light of recent discoveries of the genetic mutations that now define primary erythromelalgia, as opposed to secondary erythromelalgia, which is often associated with underlying medical disorders.

A patient with primary erythromelalgia successfully treated with misoprostol

A patient with primary erythromelalgia successfully treated with misoprostol

Current pain management strategies for patients with erythromelalgia: a critical review.

Erythromelalgia (EM) is a rare disorder characterized by erythematous, warm, painful extremities, which is often precipitated by cold conditions. The pathophysiology of EM is incompletely understood. Recent investigations have identified sodium channelopathy as a genetic cause for this pain condition, classified as primary inherited EM. Other subtypes are idiopathic EM and secondary EM. The management of pain in EM is challenging as no single therapy has been found to be effective. There is varying response to pharmacotherapy and significant variability within this clinical population, resulting in a stepwise trial and error approach. Consequently, EM is often associated with poorer health-related quality of life with higher morbidity. There is currently no consensus or guidelines on management of pain in EM. This is a review of the literature on management of pain using pharmacologic, procedural intervention and nonpharmacologic treatment in children and adults with EM.

Mutation in Nav1.7 causes high olfactory sensitivity

Mutations in the sodium-channel Nav 1.7, encoded by the gene SCN9A, are known to cause pain disorders. In particular, gain-of-function missense mutations in Nav 1.7 have been shown to be causal in primary erythromelalgia. We present a patient with erythromelalgia, pain attacks and hyperosmia with a mutation within the sodium-channel gene SCN9A. A 50-year-old woman presented with burning pain in both feet and abdominal pain attacks developed over the course of 10years. Furthermore, this patient experienced a hypersensitivity for odours. Clinical investigation as well as serum/cerebrospinal fluid laboratory findings and electrophysiological testing were unremarkable. Olfactory testing showed high olfactory acuity for all screened modalities and good intranasal sensitivity. Furthermore, quantitative sensory testing within the trigeminal area revealed very low thresholds for thermal, tactile and pain detection. In addition, quantitative sensory testing at the lower legs showed hyperalgesia and, as the disease progresses, thermal sensory function loss. Skin biopsies of the proximal and distal lower limbs revealed reduced epidermal nerve fibre density indicating small fibre neuropathy. Genetic analysis of the SCN9A gene demonstrated a heterozygous mutation in Exon 20 - c.3734A>G (p.N1245S). Treatment with clinically available sodium-channel inhibitors did not result in significant pain relief. Local application of the sodium-channel blocker ambroxol however, reduced pain intensity. Continuous odour exposure stabilised mood and induced a short-term pain relief. This clinical note illustrates the course of middle-age onset erythromelalgia and points to clinical findings related to a likely pathogenic missense mutation affecting the sodium-channel Nav 1.7. SIGNIFICANCE: This case report illustrates the course of middle-age onset erythromelalgia with presumed gain-of-function in olfactory and pain sensation associated with a Nav1.7 channel mutation.

Erythromelalgia.

Erythromelalgia is a rare syndrome characterized by the intermittent or, less commonly, by the permanent occurrence of extremely painful hyperperfused skin areas mainly located in the distal extremities. Primary erythromelalgia is nowadays considered to be a genetically determined neuropathic disorder affecting SCN9A, SCN10A, and SCN11A coding for NaV1.7, NaV1.8, and NaV1.9 neuronal sodium channels. Secondary forms might be associated with myeloproliferative disorders, connective tissue disease, cancer, infections, and poisoning. Between the pain episodes, the affected skin areas are usually asymptomatic, but there are patients with typical features of acrocyanosis and/or Raynaud's phenomenon preceding or occurring in between the episodes of erythromelalgia. Diagnosis is made by ascertaining the typical clinical features. Thereafter, the differentiation between primary and secondary forms should be made. Genetic testing is recommended, especially in premature cases and in cases of family clustering in specialized genetic institutions after genetic counselling. Multimodal therapeutic intervention aims toward attenuation of pain and improvement of the patient's quality of life. For this purpose, a wide variety of nonpharmacological approaches and pharmacological substances for topical and systemic use have been proposed, which are usually applied individually in a step-by-step approach. Prognosis mainly depends on the underlying condition and the ability of the patients and their relatives to cope with the disease.

An Atypical Erythromelalgia on the Chest.

An Atypical Erythromelalgia on the Chest.