Background Stroke in young person is less frequent than in older populations but has a major impact on the productive individuals and society. Objective To determining risk factors and etiological subtypes of cerebral infarctions in patients of young (20-49 years) age who were admitted to the First Central hospital in Ulaanbaatar, Mongolia. Methods This paper is based on a review of hospital-based studies of patients with cerebral infarction in age range 20-49 years which was conducted from 2009 to 2013. Data regarding onset of cerebral infarction, clinical manifestations, diagnostic test results of patients were examined during their hospital treatment and modified Rankin Scale scores at discharge. Subtyping of cerebral infarction was conducted in accordance with the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Results Out of total number of 1289 patients admitted for cerebral infarctions, 259 (20.1%) were in the 20-49 year age range and the male-to-female ratio was 1.3:1. The most common conventional risk factors were hypertension (39.8%), premature atherosclerosis (20.8%) and dyslipidemia (17.8%). From the rare specific risk factors in young patients with cerebral infarction were migraine with aura in combination with other risk factors and hypotension, and cerebral vasculopathies. The majority of subtype of cerebral infarction was undetermined (34.7%), followed by other determined etiologies (19.7%). Among the category of undetermined etiology, incomplete evaluation (71.1%) was predominant. Most of the patients demonstrated good functional outcomes, at the time of hospital discharge, 86.9% patients had Rankin Scale scores in the range of 0-2 points. Conclusions Young adults with cerebral infarction account for 20.1% of all stroke patients in tertiary referral hospital in Ulaanbaatar. Risk factors, including conventional and specific causes in combination relatively prevalent in young adults, and a high rate of the patients are categorized under conventional, other determined and undetermined etiologies. Cerebral infarction in the young requires a different approach to investigation and management than ischemic stroke in the elderly given differences in the relative frequencies of possible underlying causes. The results show the needs for persistent management of conventional risk factors and properly patient investigation to determine etiology of cerebral infarction in young patients in Mongolia.

Background Ischemic stroke or cerebral infarction in young adults (20-50 years) is relatively frequent, accounting for more than 10%-26% of all first strokes and its incidence rises steeply with age. Causes of “Young stroke” are heterogeneous and while it generally has a good prognosis, it has a significant socioeconomic impact, including functional deficits and financial costs. The most frequent causes of cerebral infarction in young adults are cardio-embolism, hypertension, premature atherosclerosis, migraine, smoking and hypercoagulable states. Objective The aim of this study was to compare characteristics of cerebral infarction between young (20-49 years) and old (50-89 years) patients undergoing investigations and treatment according to one common protocol in the tertiary hospital. Methods This Descriptive case series study was conducted in Department of Neurology of First State Central Hospital from October 2014 to July 2016. During this study, we observed 220 patients with first-onset of cerebral infarction from which 90 young patients (under 50 years) and 130 old one (above 50 years), based on prospective study. Data regarding the etiology and risk factors of the stroke, clinical manifestations, and diagnostic test results of patients were examined during their hospital treatment as well as a NIHSS, modified Rankin Scale scores, and Barthel Index at admission and discharge, also at 21 day. Stroke subtyping was conducted in accordance with the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Results In total, 220 patients with cerebral infarction were included, from which 90 (40.9%) were 20-50 years and 130 (59.1%) were 50-89 years. The proportion of males was higher among both groups: 61.1% vs. 70.0%. Common causes for cerebral infarction in the young patients were current smoking (53.3.1% vs. 37.8%), long-term alcohol consumption (51.1 vs. 12.3), cardiac embolism (36.0% vs. 16.2%), migraine with aura (25.5% vs. 12.2%), infective diseases (15.6% vs. 0.8%), and oral contraceptive use (14.4 vs. 0%). Leading causes for ischemic stroke in old patients were the conventional risk factors such as hypertension (75.4% vs. 38.9%), atherosclerosis (66.9% vs. 31.1), coronary artery disease (24.3% vs. 12%), and diabetes mellitus (26.9% vs. 6.7%). Most of the young stroke patients demonstrated good functional outcomes, at the time of discharge (71.1% vs. 60%) and three weeks (86.6% vs. 66.2%) patients had Rankin Scale scores in the range of 0-2. Conclusions There are significant differences between young and old patients with cerebral infarction regarding to risk factors, etiological subtypes and improvement of functional deficits associated with the stroke. However, severity of stroke on admittance is similar but three weeks outcome is different among young and old patients with relatively rapid improvement of functional deficit in young stroke patients than old one.

Stroke is a major healthcare problem ranking as the second leading cause of death and the first cause of disability in the world. The stroke incidence in the world varied from 100 to 336 per 100.000 people per year. In different world regions the incidence of stroke ranges between 134.9 to 336.3 new cases per 100.000 inhabitants and the annual frequency of deaths within 36.7 to 136.7 per 100.000 events, while the frequency of stroke and mortality in Mongolia is within the upper limits of the above mentioned indicators. A recent report of the WHO MONICA Project documented that stroke incidence ranged between 101-285 in males and 47-198 in females per 100,000 people aged 35 to 64 years in 16 countries involved in this study. In the United States the average annual incidence rates of all strokes under the age of 55 years was 113.8 per 100,000, while that for cerebral infarction was 73.1 per 100,000. More than 10% of patients with cerebral infarction were 55 years or younger. Almost two thirds of the global burden of stroke is borne by those in developing countries. Recent study in Mongolia showed that young adults account for 21%-26% of all stroke patients as opposed to 10%-13% Western countries. In this review we sought to discuss the tissue-based definitions, epidemiological trends, risk factors, and specific causes associated with stroke in the young.

Background: Acute respiratory viral infection caused by human new coronavirus that was reported in last December of 2019, is becoming the most serious issue worldwide. During human coronavirus infection, upper and lower respiratory symptoms are common. However, other systemic symptoms, especially neurological signs were reported previously. It is further noted that sometimes the neurological manifestations can precede the typical features like fever and cough and later on typical manifestations develop in these patients. Purpose: to analyze information of neurological manifestations related to COVID-19 disease and possible way of affection of nervous system by SARS-CoV-2 virus. Material and Methods: We searched Medline, PubMed, Central and Google Scholar, Web of Science for related published articles and case reports, using keywords such as “COVID-19”, “Coronavirus”, “pandemic”, “SARS-CoV-2”, “Neurological manifestations”; “Complications”; “Clinical characteristics”. There were found and considered few articles of clinical characteristics and case series reports related to COVID-19 with neurological manifestations and complications, also articles of SARS-CoV-2 virus affection to nervous system. Results Neurological manifestations including headache, dizziness, myalgia, confusion, and hyposmia were observed during COVID-19 in 6-36.4% cases. A few cases with COVID-19 showed more severe symptoms such as stroke, polyneuropathy, encephalopathy, myelitis and acute necrotizing encephalitis. SARS-CoV-2 viral infection pathway may be two different ways, namely, a) binding ACE-2 receptor on capillary endothelium and causing inflammation where then can cross blood-brain barrier and to emerge brain tissue damage; b) entering via nasal epithelium where the bipolar cells locate, from there directs to central nervous system to cause neuronal injury through olfactory bulb.
Conclusion: neurological manifestations are relatively common in COVID-19, however, there is lack of evidence-based study. There may have two possible pathways of SARS-CoV-2 to affect nervous system, but is required necessary further elaborately study

Introduction: However MS having been diagnosed in Mongolia during the last 40-50 years, there are difficulties in its differential diagnoses from other demyelinating diseases. Therefore our main reasons are to do study the clinical characteristics of MS with comparison MRI findings.Goal. To determine the clinical characteristics of MS with correlations to MRI-findings using caseobserved methods.Materials and Methods: Used the “door-to-door” method to be find out and work with that 115 subjects, from which selected according to the diagnostics criteria 67 patients with following reexaminations for confirmation of diagnosis, during next 2 years these cases were studied with MRI and VEP to compare clinical manifestations, common forms by age and sex. 34 subjects for MRI and 6 patients for VEP examinations undergone respectively; SPSS-15.0 used to analyze collected materials; for description of the data used mean, median, standard deviation; to detect inter variable association used “t”-test, “Chi-square”, correlation coefficient; P-value for all significant cases.Results:Among sixty-seven MS patients the main clinical forms were cerebrospinal (55 patients – 82.1%), pure cerebral (4 patients–6.0%) and pure spinal–(8 patients–11.9%). Clinical course was relapsingremitting in 39 patients (58.2%); secondary-progressive in 12 patients (17.9%); progressiverelapsing in 13 patients (19.4%), and primary-progressive in 3 patients (4.5%). The most common location of first attacks was pyramid system–46,3%, visual pathway, predominantly causing damage to the optic nerve–43.3%, followed by the spinal cord - 37.3%, optic-spinal-20.9% and brainstem–10.3%. Pyramid, sensory and vision-dissociated symptoms were also reported in 77% of patients, and paroxysmal symptoms in 67% of patients. The MRI scan performed in 34 patients–50.7% determined dissemination-in-time 10(29.4%) and in-space 18(53%). On MRI scans in T2-weighted images, 16 hyperintense lesions within the periventricular white matter were found (56,3%); 3 lesions in area pons and cerebella (5,95%); 13 lesions in spinal cord white matter (30,4%) and 2 lesions in nervous opticus tract (7,45%). Conclusions: The main clinical forms were cerebrospinal (82%) and opticospinal, which formed more than half of the cases, in which relapsing-remitting (58%) and progressive-relapsing courses (19%) predominated. The relapsing and progressing course of the disease was directly determined by clinical symptoms and MRI scan findings of dissemination-in-time and in-space of existing lesions. As MS can be asymptomatic, it was found that MRI-findings were positive (11.8%) even when clinical manifestations disappeared.

Background: Migraine is a chronic and recurrent vascular headache, and is one of the most common diseases in the general population. Evidence suggests that migraine is associated with an increased risk of silent infarct lesions and high signal intensities observed at the time of performing magnetic resonance imaging (MRI). Objectives: To determine the frequency of hyperintense foci in migraine patients and the relationship with migraine headache characteristics and cerebrovascular risk factors. Material and Methods: Eighty patients with migraine headache (31 with aura and 49 without aura) were enrolled and interviewed. Twenty headache-free individuals of the same age range were used as controls. Information of patients with migraine, on their headache characteristics (severity, frequency, and mean disease duration) and other related data was obtained by completing a clinical checklist. Subsequently, brain magnetic resonance imaging (MRI) was performed in the study and control groups, and each patient was then evaluated for hyperintense lesions. Results: Of the 80 patients with migraine, 26 (32.5%) had silent hyperintense infarct lesions on MRI scan while the age-matched control group (n=20) did not found such abnormalities (32.5% vs 0%). The mean age of the patients with hyperintense foci was 38.9 years while those with no lesions was 31.3 years (p<0.001). Amongst the 65 hyperintense lesions detected in this study, both side supratentorial foci represented in 61.5% patients (n=40) in the whole brain, while 38.5% of the lesions (n=25) were found in subtentorial white matter. Cerebrovascular risk factors such as serum cholesterol, oral contraceptive use, and body mass index (BMI) were not significantly different in these two age groups (p>0.05). The lesions were found significantly more frequently in the female patients who experienced chronic migraine with aura and smoking (p=0.05). Conclusion Our study shows that disease duration has a key role in the formation of hyperintense brain lesions. Certain cerebrovascular risk factors such as serum cholesterol, oral contraceptive use and BMI, do not affect the presence or absence of such lesions, suggesting that the relationship between migraine and these lesions may be directly due to the effects of migraine itself.

Background: The frequency of cerebral infarction and stenosis of intra- and extracranial arteries may be vary with age-group and gender. Objective: This study was conducted to clarify the risk factors and characteristics of cerebral infarction and stenosis of vessels in Mongolian young adults. Methods: This was a prospective study, from October 2015 to July 2020, of 100 patients below 50 years diagnosed with acute cerebral infarction. Patient characteristics were compared according to sex (61 males and 39 females) and age group (29 patients were below 34 years and 71 patients were 35–49 years). Characteristics of acute cerebral infarction were studied by DWI-diffusion weighted MRI imaging. Stenosis of intra- and extracranial arteries was diagnosed by duplex sonography, head and cervical magnetic resonance angiography (MRA). Results: Leading causes for cerebral infarction in the young patients were hypertension (71%), smoking (57%), dyslipidemia (45%), diabetes (33%), and migraine with aura (25%). Lacunar Infarction was most common in our patients (33%). Partial anterior circulation infarction was predominant in males (45.9% vs 38.5%; P<0.05) and posterior circulation infarction in females (23.1% vs 11.5 %; P<0.05). Small artery atherosclerosis was found in 33% cases, with higher prevalence in patients of the 35–49 years age-group. Intracranial stenosis was more common than extracranial stenosis, and middle cerebral artery stenosis was most prevalent (38.9%). Stenosis in the anterior circulation was more frequent than in the posterior circulation (P<0.001). Conclusions In these young patients, hypertension, smoking, dyslipidemia, diabetes, and migraine with aura were common risk factors. Intracranial stenosis was most common, particularly in the middle cerebral artery.

Background: Data from yearly statistical reports on morbidity and mortality in Mongolia show that young adults account for approximately 20-26% of all stroke patients as opposed to 10-13% in Western countries. Objectives: The aim of this study was to compare characteristics of ischemic stroke between young (20-49 years) and old (50-79 years) patients undergoing investigations and treatment according to one common protocol in a tertiary hospital. Material and Methods: This hospital based prospective study included 110 young and 130 old patients with acute ischemic stroke. Data regarding the etiology of the stroke, diagnostic neuroimaging test results and degree of functional improvement of patients were examined during their observation. Results: The frequency of ischemic stroke at the age of 20-49 years grows from 9.6% to 24.2% and is predominant in the male sex (17.1%), which indicates a young stroke in mongolians is not uncommon. Young adults with ischemic stroke frequently bear both traditional and specific vascular risk factorsthan elderly people (p<0.05). The most common TOAST subtype in the young and old groups was undetermined (26.4% vs.12.3%; p=0.004), other determined cause (22.7% vs. 6.9%; p<0.001), and cardioembolism (20.0% vs. 22.3%) followed by Large-artery atherosclerosis (17.3% vs. 26.2%) and small vessel occlusion (15.6% vs. 33.8%; p<0.001). Partial anterior circulation infarcts were more common among young patients (p<0.001), than in posterior circulation infarcts. Silent brain infarcts and leukoaraiosis are not uncommon brain imaging findings (<0.05) in hypertensive and migraineur patients and should not be overlooked due to their potential prognostic relevance. Outcomes in young adults with hemispheric ischemic stroke can safely be improved with Low- molecular-weight-heparin therapy (OR 1.58; 95% CI, 0.99-2.51; p=0.001).
There were large differences between two groups concerning the 6-month outcome which showed beneficial effect for young stroke patients (mRS:89.1% vs. 66.9%, p=0.002; BI: 84.2% vs.73.1%). Conclusion There are significant differences between young and old patients with ischemic stroke regarding to risk factors, etiological subtypes and improvement of functional deficits associated with the stroke. However, severity of stroke on admittance is similar but six weeks outcome is different among young and old patients with relatively rapid improvement of functional deficit in young stroke patients than old one (mRS: 89.1% vs. 66.9%, p=0.002; BI: 84.2% vs.73.1%).

BACKGROUND. Sensorineural hearing impairment (SNHI) is the most common inherited sensory defect, affecting about 3 per 1000 children. More than 50% of these patients have a genetic cause (i.e. hereditary hearing impairment; HHI). Mutations in certain genes were noted to be extraordinarily popular in the deaf patients across different populations, making molecular screening feasible for these common deafness genes. One of the most important characteristics that we have learned concerning hereditary hearing loss is that common deafness genes and their mutations are usually different according to the ethnic background. As demonstrated in our previous studies performed in Taiwanese patients, the mutation spectrums of common deafness genes, such as the GJB2 gene and the SLC26A4 gene, are different from those in the Caucasian or even other Asian populations. These findings further underscore the indispensability of the collection of local data in terms of genetic counseling. In the collaborative project, we have successfully established a cohort of >100 hearing-impaired families, and clarified the genetic epidemiology of deafness in the Mongolian population. We identified several special deafness mutations such as GJB2 c.23+1G>A, c.559_604dup, and SLC26A4 c.919-2A>G, and our results revealed that Mongolian patients demonstrate a unique genetic profile in deafness as compared to other East Asian populations (paper in preparation). Meanwhile, by organizing a seminar at National Taiwan University Hospital in March 2017, we have transferred crucial concepts and techniques regarding how to perform genetic testing for deafness to the Mongolian colleagues. In the future, we plan to strengthen the mutual collaboration by expanding the clinical cohort and upgrading the genetic examination platform using the NGS techniques.

BACKGROUND. Sensorineural hearing impairment (SNHI) is the most common inherited sensory defect, affecting about 3 per 1000 children. More than 50% of these patients have a genetic cause (i.e. hereditary hearing impairment; HHI). Mutations in certain genes were noted to be extraordinarily popular in the deaf patients across different populations, making molecular screening feasible for these common deafness genes. One of the most important characteristics that we have learned concerning hereditary hearing loss is that common deafness genes and their mutations are usually different according to the ethnic background. As demonstrated in our previous studies performed in Taiwanese patients, the mutation spectrums of common deafness genes, such as the GJB2 gene and the SLC26A4 gene, are different from those in the Caucasian or even other Asian populations. These findings further underscore the indispensability of the collection of local data in terms of genetic counseling. In the collaborative project, we have successfully established a cohort of >100 hearingimpaired families, and clarified the genetic epidemiology of deafness in the Mongolian population. We identified several special deafness mutations such as GJB2 c.23+1G>A, c.559_604dup, and SLC26A4 c.919-2A>G, and our results revealed that Mongolian patients demonstrate a unique genetic profile in deafness as compared to other East Asian populations (paper in preparation). Meanwhile, by organizing a seminar at National Taiwan University Hospital in March 2017, we have transferred crucial concepts and techniques regarding how to perform genetic testing for deafness to the Mongolian colleagues. In the future, we plan to strengthen the mutual collaboration by expanding the clinical cohort and upgrading the genetic examination platform using the NGS techniques.