Current article provides an overview of the results of epidemiological studies of chronic inflammatory demyelinating polyneuropathy (CIDP) in Russia and abroad. It is shown that the prevalence of CIDP is different in countries, due to the use of different diagnostic criteria. It should be noted that the reliability of epidemiological prevalence and incidence is affected by difficulties of diagnosis of atypical forms of the disease.

Analysis of motor unit potentials (MUPs) parameters registered by needle EMG electrodes is the key for understanding changes of the motor units in different neuromuscular disorders. The classification of MUPs changes known as electromyographic stages (EMGS) of the denervation/reinnervation process (DRP) is based on the analysis of myogenic, synaptic neurogenic and neuronal disorders. Current article focuses on pathogenesis of typical and atypical MUPs of low duration, decreased and increased amplitude, additionally muscle biopsy data and neurophysiological assessment of muscle fiber density, and мacro-EMG. The absence of primary neurogenic disturbances in inflammatory and non-inflammatory muscle diseases, as well as in neuro-muscular junction disorders, confirmed by single fiber EMG and мacro-EMG makes it impossible to discuss the concept of EMG stages in patients with these levels of pathology. The EMG stages concept can be applied for peripheral nerve and motor neuron disturbances only, reflecting the volume but not the efficiency of reinnervation.

The stimulator of tissue regeneration Actovegin is used in many diseases associated with blood circulation. It’s given to patients with neurological, endocrinological, cardiac and even ophthalmic diseases. Its efficacy is observed in disorders of the brain with the metabolic and vascular nature. It improves the trophism of tissues with injuries, burns and ulcers of the different etiology. It prevents the development of adverse effects as a result of peripheral vascular disorders. Actovegin has received the active application in patients with the long-standing diabetes as a prevention and the treatment of complications, particularly the vascular dementia and the diabetic distal polyneuropathy. The basis for these diseases is the hypoxic nature of the tissue damage. It’s mechanisms direct to the reduction of the influence pathological factors and the recovery of the antioxidant activity of cells.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized with lesions of both upper and lower motor neurons. In accordance with modern diagnostics criteria, only clinical symptoms are used for revealing lesions of the upper motor neuron with the ALS, which often causes serious difficulties. Absence of the pyramidal syndrome does not allow diagnosing ALS, and the diagnosis of progressive muscular atrophy should be set in these cases. We describe a case of an isolated generalized lesion of the lower motor neuron with the signs of cortical motor neurons lesion revealed in the course of navigational transcranial magnetic stimulation. Possible reasons for difficulties in detecting pyramidal syndrome are discussed together with the necessity of working out the criteria of instrumental diagnostics of lesions of the upper motor neuron in ALS.

The case of stiff-person syndrome with benign course in 16-years old patient is presented. The initial clinical signs of the disease were observed in infancy with retarded development of motor functions and skeleton muscle lumps. The diagnosis was made using generally accepted clinical and electromyographical criteria. Aspects of differential diagnosis, pathogenesis and clinical course polymorphism in early-onset cases of the disease are discussed.

Mitochondrial neurogastrointestinal encephalomyopathy syndrome (MNGIE) is a rare autosomal recessive progressive multisystem disorder. Most of MNGIE is caused by mutations in the gene encoding thymidine phosphorylase (TYMP), locus 22q13. Mitochondrial dysfunction represents multiple deletions and depletion of mtDNA. We present a case of MNGIE with a novel mutation in the position c.1001T>G of TYMP gene, hypergonadotropic hypogonadism, decrement of compound muscle action potential following repetitive nerve stimulation on EMG which was not previously described in literature and differential diagnoses MNGIE with other conditions.