Background. Nitrous oxide abuse (“laughing gas”, N2O) is common among young people attending nightclubs. Contrary to popular belief about the safety of N2O, in some cases neurological complications develop due to a deficiency of vitamin B12, the activity of which is blocked by N2O. Purpose of the study – to determine the typology and course of neurological disorders in a group of patients who regularly use “laughing gas”. To note the key diagnostic markers that allow verification of vitamin B12 deficiency induced by nitrous oxide consumption. To describe pathogenetic therapy features and follow-up. Materials and methods. The study included 12 patients (10 men and 2 women) aged 18 to 45 years (average age 29 years) with a diagnosis of B12-deficient myelopolyneuropathy induced by regular use of nitrous oxide. Results. The most common neurological complication of nitrous oxide abuse for more than 1 month was a generalized lesion of the peripheral nerves with acute or subacute distal symmetric sensory or sensorimotor axonal polyneuropathy. In the clinical picture, sensory complaints and disorders prevailed. Paresis developed in half of the cases. A typical neuroimaging symptom characteristic of funicular myelosis was rarely detected (16.7 %). A decrease in B12 vitamin level could most reliably be diagnosed only indirectly, by the presence of hyperhomocysteinemia (91.7 % of cases). In all cases that were followed-up, prolonged therapy with cyanocobalamin led to partial (n = 5; 62.5 %) or complete (n = 3; 37.5 %) regression of neurological symptoms. Conclusion. Caution regarding the use of nitrous oxide should be in all cases of predominantly sensory polyneuropathy with acute or subacute development in young and middle-aged people. A thorough history taking (targeted survey on the fact of nitrous oxide consumption) and diagnostics (testing the level of homocysteine, if possible methylmalonic acid) allow you to not miss a deficiency of vitamin B12, the treatment of the consequences of which with timely verification and adequate correction is quite effective. It is recommended that the level of homocysteine in the blood to be regularly monitored during the treatment (in order to achieve its normalization).

Болевой синдром является важной социально-экономической проблемой. Брахиалгия занимает ведущее место среди причин обращений к врачу. В настоящем обзоре литературы представлен спектр неврологических и других органических причин брахиалгии, описаны особенности болевого синдрома при разных нозологиях.

Background. Carpal tunnel syndrome is the most common compression mononeuropathy. The choice of the preferred conservative treatment method is still relevant, especially for the patients with the moderate severity of the disease. Objective: to perform a comparative study of the effectiveness of local injection therapy and wrist splinting in idiopathic moderate carpal tunnel syndrome; to assess the duration of the clinical effect in the follow‑up period to 6 months. Materials and methods. The study included 105 cases of moderate idiopathic carpal tunnel syndrome. Patients were randomized to 2 groups depending on the treatment method: the main group (n = 54) received 1 or 2 ultrasound‑guided injections with glucocorticosteroid (betamethasone 5 mg + 2 mg/1.0 ml) and lidocaine 2 % 1.0 ml into the carpal canal; the control group (n = 51) was assigned wrist splinting at night for 1 month. The primary criterion for therapy effectiveness was evaluation by clinical scales (SSS, FSS, LANSS, Visual Analogue Scale) after 1 month from the treatment initiation. A secondary criterion for the therapy effectiveness was the assessment of changes in electrophysiological and neurosonographic parameters.Results. The scores for SSS, FSS, LANSS and Visual Analogue Scale were significantly lower at 1 month in the injection therapy group than in the splinting group (p <0.0001). A significant change in the electrophysiological parameters of the median nerve (a decrease the distal motor and sensory latency, an increase in the Mand S‑response amplitude, an increase in sensory conduction velocity on the hand) and a significant decrease in the cross‑sectional area of the median nerve at the level of the pisiform bone was noted only in the local injection therapy group. The average duration of the local injection therapy clinical effect surpassed the splinting one and reached 4 months.Conclusion. After 1 month from the start of the treatment, the local injection therapy demonstrated a higher clinical efficacy compared to the wrist splinting, the average duration of the effect reached 4 months. This conservative treatment method is preferred for the patients with moderate idiopathic carpal tunnel syndrome.