Nitrous oxide (NO) intoxication is a common consequence of its inhalation with recreational purpose, which is prevalent among young people. The most severe result of such an entertainment is development of myelopolyneuropathy with polyneuropathy as the most common presentation, which may start acutely or subacutely. The underlying cause of neurological complications of NO intoxication is deficit of B12 vitamin, however its laboratory confirmation may be challenging. The key aspect of treatment of neurological symptoms in such patients is prescription of adequate dosage of B12 for a long period of time. In this paper we present the clinical case, which demonstrates challenges of vitamin B12 deficiency verification and advantages of oral cyanocobalamin prescription.

Introduction. Chronic inflammatory demyelinating polyneuropathy (CIDP) is characterized by long-term progressive or relapsing course, neurological deficit, and disability of varied severity. The course of CIDP after specific therapy and, if necessary, long-term maintenance treatment are to be studied. Objective: To evaluate CIDP clinical and history characteristics over the long-term follow-up ( 5 years), to compare long-term CIDP course in a number of clinical variants and onset types, and to determine clinical predictors of unfavorable CIDP course. Materials and methods. The study included 45 patients diagnosed with CIDP based on EAN/PNS 2021 criteria lasting for 5 or more years. Retrospective collection and analysis of medical records and clinical history were performed. Internationally accepted scales were used to assess neurological deficit (NIS, MRCss), disability (INCAT), and disease activity status (CDAS). The criteria of unfavorable course were developed to evaluate factors affecting CIDP course. Results. Among the patients with CIDP history of 5 years, each third (34%) had no neurological deficit and remained in long-term clinical remission (CDAS 1). The vast majority (90%) responded to first-line therapy in early disease, while only 53% of patients required maintenance treatment in 5 or more years of the onset. With the developed criteria (poor response to glucocorticosteroids (GCS), need for maintenance therapy, and CDAS 3–5), unfavourable CIDP course was detected in 24 (53.3%) participants. Its probability increased in later onset (47 [30; 50] years), the chronic type of onset, and delayed specific therapy. The most significant predictors included low total NIS score at onset (60 points) and multifocal CIDP. Conclusions. The course of typical CIDP is relatively favorable if timely diagnosed, and pathogenetic treatment initiated. Patients with acute and subacute onset demonstrate the best long-term status. The predictors of unfavourable disease course include mild neurological deficit at onset (NIS total score 60 points) and multifocal CIDP.

Background. A clinical application of scales and questionnaires is essential for the objective evaluation of treatment response, disease course, quality of life and the disability level in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Neuropathy Impairment Score (NIS) has become widespread in epidemiological and clinical studies of various polyneuropathies, including CIDP. However, its application in Russia is limited by the absence of its validated version for Russian-speaking patients. Aim. To develop the Russian validated version of the NIS for its application in patients with CIDP. Materials and methods. The study involved 50 patients with CIDP (25 with multifocal variant of CIDP (Lewis–Sumner syndrome) and 25 with typical CIDP). The validation process included two stages: translation and linguocultural ratification of the scale according to the standard protocol and an assessment of its psychometric properties, such as reliability, validity and sensitivity. Results. The developed Russian version of the NIS demonstrated the high level of reliability, sensitivity and validity. Conclusion. The validated Russian version of the NIS can be recommended for application in research and clinical practice.

Background. The use of rating scales and questionnaires is essential in an evaluation of disease course, treatment response, the disability level and quality of life in patients with chronic inflammatory demyelinating polyneuropathy. The Medical Research Council (MRC) scale and its modification Medical Research Council sum score (MRCss) are widely used for measurement of motor deficit in patients with neuromuscular disorders. However, its usage is limited by the absence of the validated version for Russian-speaking patients.Aim. To validate MRCss scale in patients with chronic inflammatory demyelinating polyneuropathy with development of a Russian version.Materials and methods. We enrolled 50 patients with chronic inflammatory demyelinating polyneuropathy (25 with typical chronic inflammatory demyelinating polyneuropathy and 25 with Lewis–Sumner syndrome). At the first step we conducted linguocultural ratification according to the standard protocol. At the second step the psychometric parameters were evaluated, such as reliability, validity and sensitivity.Results. The developed Russian version of MRCss scale demonstrated the high level of reliability, validity and sensitivity.Conclusion. As a result, we developed a validated Russian version of MRCss scale, recommended for clinical practice and research.

Background:Hypokalemic periodic paralysis (HypoKPP) is a rare neuromuscular genetic disorder causing recurrent episodes of flaccid paralysis. Most cases are associated with CACNA1S mutation, causing defect of calcium channel and subsequent impairment of muscle functions. Due to defined management approaches early diagnosis is crucial for promptly treatment and prevention new attacks.Materials and methods:We report a case of HypoKPP associated with previously unreported mutation in CACNA1S gene (p.R900M). Molecular modeling of CaV1.1 was applied to evaluate its pathogenicity.Results:As a patient referred between attacks neurological status, laboratory and neurophysiological examination were unremarkable. Molecular modeling predicted that the p.R900M mutation affects the process of calcium channels activation.Conclusion:Novel CACNA1S mutation, associated with HypoKPP was identified. Monte-Carlo energy minimization of the CaV1.1 model supported the association of this mutation with this disease.

Introduction. Despite the improving diagnostic criteria for the chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), its verification is still an issue. Objective: to study the rate and the causes of CIDP misdiagnosis. Materials and methods. We prospectively and retrospectively analyzed the clinical and paraclinical data of 223 patients admitted to the Research Center of Neurology from 2018 to 2022 with a CIDP referral. Results. We revised the CIDP diagnosis in 150/223 patients (67%; median age 55.5 [43; 63] years; 75 males and 75 females; 3-year follow-up history [1.75; 5.25].) Once the definitive diagnosis was clarified, we divided the patients into the following groups: polyneuropathy of other etiology (n = 94; 63%), other neuromuscular disorders (n = 39; 27%), CNS disorders (n = 10; 7%), no structural NS disease (n = 7; 5%). Patients did not meet the 2021 EAN/PNS diagnostic criteria at the history-taking stage in 65% of cases, at the neurological examination stage in 39% of cases, and at the electroneuromyography stage in 92% of cases. Conclusions. The rate of CIDP misdiagnosis in Russia is 67%, and most often this refers to patients with polyneuropathy of other etiologies. The main cause for the CIDP misdiagnosis was inaccurate electroneuromyography. We should bear in mind that CIDP is a rare disorder with an extensive differential diagnosis, so it should be verified according to the current 2021 EAN/PNS diagnostic criteria.

Background. Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common immune‑mediated polyneuropathy. CIDP is characterized by a long‑term progressive or recurrent course of the disease and the development of neurological deficits and disability, it is important to assess the quality of life of patients. The paper presents the results of the first and second steps of validation of the Chronic acquired polyneuropathy – Patient Reported Index (CAP‑PRI) questionnaire designed to assess quality of life in patients with immune‑mediated polyneuropathy.Aim. To develop the Russian version of the CAP‑PRI questionnaire.Materials and methods. 85 patients with CIDP (according to EAN / PNS 2021 criteria) were enrolled. At the first step we conducted linguocultural validation according to the standard protocol. Two Russian‑speaking professional translators in the field of medicine performed direct translation of the original English‑language questionnaire, and the back translation was performed by native speakers with a medical background. At the second step the psychometric parameters were evaluated.Results. The developed Russian version of the CAP‑PRI questionnaire demonstrated a high level of reliability, validity and sensitivity.Conclusion. The Russian version of the CAP‑PRI questionnaire is recommended for clinical practice and research. In addition, the relationship between improved quality of life and the reduction of neurological deficits, disability and fatigue (as assessed by the IRODS, NIS and FSS scales) has been shown.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a heterogeneous treatable dysimmune neuropathy. The variety of clinical forms and course of the disease can be challenging for proper diagnosis and early treatment. In a quarter of cases CIDP starts acutely, mimicking GuillainBarr syndrome. The early diagnosis is especially important regarding differences in treatment and prognosis of these conditions. In this article, we present a clinical case of acute onset CIDP with a detailed analysis of the differential diagnosis between acute and chronic immune-mediated neuropathies.

Background. Chronic inflammatory demyelinating polyneuropathy (CIDP) is a treatable dysimmune polyneuropathy. An objective response for pathogenic therapy is essential in diagnosis and management of CIDP. For proper assessment of patient’s complaints and evaluation of disease progression, it is recommended to use validated scales and questionnaires. The paper presents the results of the first step of Inflammatory Neuropathy Cause and Treatment (INCAT) validation in patients with CIDP.Objective: the development of the Russian version of the INCAT scale and its linguocultural ratification.Materials and methods. 15 patients with definite CIDP (according to EFNS/PNS criteria) were enrolled. Linguocultural ratification was conducted according to the standard protocol.Results. The Russian version of the INCAT scale was developed.Conclusion. We conducted the first stage of INCAT scale validation in patients with CIDP.