Ischemic stroke (IS) in young adults is reported as uncommon, comprising less than 10% of all stroke patients 1 . However, In our clinical practice, we are faced not infrequently with patients aged less than 45 years who suffered a stroke, many of them with no risk factors for atherosclerosis and no ultimate clear etiological diagnosis even after a thorough investigation. This diagnostic challenge is one of the main scopes of studying and researching mechanisms of brain ischemia in young adults in addition to the dramatic personal, familial, and socio-economic consequences by affecting individuals at the top of their productive age.Although cardioembolism and cervicocephalic arterial dissection have been established as principal etiological factors of IS in young adults 2 , a systematic diagnostic approach must be applied to all patients, regarding the great number of potential causes in this group and the multifactorial nature in many of these patients.Despite more accurate diagnostic tools recently acquired in vascular imaging, hematological and genetic studies, currently, the number of young patients with cryptogenic IS remains high, performing 30-40% 3,4 . Considered an unusual cause of IS in the young two decades ago 5 , atherosclerosis has gaining projection by recent reports of significant raise in traditional risk factors as hypertension, diabetes, obesity, dyslipidemia and tabagism among hospitalized adolescents and young adults 6. Table 1 shows the main categorizations of etiologic subtypes of IS in young adults that must be considered in every young patient with IS.
NoNAthERoSclERotIc ANgIopAthIES
AbStRActStroke affects mainly people aged over 65 years, and atherosclerosis predominates as the main etiopathogenic factor in ischemic stroke (IS). On the other hand, cardiac embolism and arterial dissection are the most frequent causes of IS in patients aged less than 45 years. However, inappropriate control of traditional vascular risk factors in young people may be causing a significant increase of atherosclerosis-related IS in this population. Furthermore, a variety of etiologies, many of them uncommon, must be investigated. In endemic regions, neurocysticercosis and Chagas' disease deserve consideration. Undetermined cause has been still reported in as many as one third of young stroke patients.Key words: stroke, brain ischemia, young adult.
RESumoA doença aterosclerótica é o fator etiopatogênico mais importante no acidente vascular cerebral isquêmico (AVCI), afecção que acomete predominantemente pessoas acima da sétima década de vida. Entretanto, nos adultos jovens a aterosclerose exibe frequência menor, sendo a embolia de origem cardíaca e as dissecções arteriais as causas mais comuns de AVCI em pacientes com até 45 anos de idade. Porém, o controle inadequado dos fatores de risco vascular nas faixas mais jovens da população pode estar levando à elevação significativa no nú-mero de infartos cerebrais associados à aterosclerose nessa faixa etária.Uma ampla gama de fatores etiológicos, muitos deles rar...