The limbic system is a complex set of brain structures that support a variety of functions, including sense of smell, instinctive behavior, emotions, memory, sleep, wakefulness and many others. It includes the olfactory bulb, olfactory tract, olfactory trigone, anterior perforated substance, cingulate gyrus, parahippocampal gyrus, dentate gyrus, hippocampus, amygdala, hypothalamus, mammillary body and midbrain reticular formation. The term "limbic encephalitis" means that the main area affected by inflammation or swelling appeared to be the part of limbic system. The core symptoms are subacute development of cognitive disorders, seizures, impairment of consciousness, sleep disturbances, some psychiatric symptoms (such as depression, irritability, hallucinations) and subacute development of short-term memory deficits. The main causes of limbic encephalitis are autoimmune process (paraneoplastic or non-paraneoplastic) and infections. The paper presents the full etiology-based classification of limbic encephalitis with the description of laboratory and radiologic findings specific for different forms of the disease.

Arnold-Chiari malformation (ACM) is a group of congenital hindbrain malformations affecting the structural relationships between the cerebellum, brain stem, top cervical spinal cord, and bones of the skull base. In clinical practice, ACM types 0 and 1 are more common and types 2, 3, and 4 belong to rare severe (often fatal) congenital malformations.Objective: to study gender differences in the incidence of ACM types 0 and 1 in outpatient neurological practice.Patients and methods. A total 2039 case records of outpatients who had visited a neurologist of the Krasnoyarsk University clinic in 2008–2014 were analyzed. Neurological and neuroradiological (1.5 Tesla brain magnetic resonance imaging, phase-contrast spinal cerebral fluid flow imaging) diagnostic techniques were used. 3.4% (70/2039) of cases were randomized according to the criteria of inclusion and exception. An entire sample included 70 ACM patients (median age, 25 [17; 34] years) (30 (42.8–7.1%) men and 40 (57.2–7.1%) women).Results. There was an increase in the incidence of ACM type 1 in the women than in the men. Conclusion. It is necessary to develop a new strategy for the prophylactic medical examination of patients with ACM to improve primary and specialized outpatient health care.

A clinical case of the development of therapeutic side effects in an epileptic woman of childbearing age is presented. The development of therapeutic side effects occurred on the background of an intermediate therapeutic dose of a valproic acid formulation and was associated with primary (idiopathic) and secondary (valproate-induced) impairments to the folate cycle on the background of a combination of a polymorphism in the CYP2C9*3 gene and a mutation in the MTHFR gene.

A clinical case of the development of undesirable pharmacological phenomena in a woman of childbearing age with epilepsy is described. The development of undesirable pharmacological phenomena at reception of average therapeutic doses of valproic acid has been caused by the primary (idiopathic) and secondary (valproate-induced) infringement of a folic cycle against a combination of CYP2C9*3 gene polymorphism and a mutation in the MTHFR gene.