Objective To investigate the correlation between vitamin B

12

levels and short-term prognosis of patients with acute lacunar cerebral infarction.Methods Fifty-six patients with acute lacunar cerebral infarction treated in a hospital in Chongqing from June 2020 to February 2021 were selected and studied in a retrospective cohort study.Using the median vitamin B

12

level(median serum vitamin B

12

of 227 pg/mL) as the cut-off point

all patients were equally divided into 2 groups:the high vitamin B

12

group(vitamin B

12

level 229-1 047 pg/mL)and the low vitamin B

12

group(vitamin B

12

level 81—227 pg/mL)

with 28 cases in each group.The age

gender

chronic disease status（hypertension

diabetes mellitus）

smoking history

modified Rankin Scale（mRS）score（to assess patient prognosis;poor prognosis was defined as mRS

>

2）

and relevant examination indexes were analyzed univariately in the 2 groups.Factors with P

<

0.30 in the univariate analysis were subjected to binary logistic regression analysis.Results There was no statistically significant difference between the 2 groups when comparing general information such as age

gender composition

whether they had hypertension

whether they had diabetes mellitus

and Fazekas score（P

>

0.05）.The proportion of patients with mRS

>

2 at discharge was lower in the high vitamin B

12

group than in the low vitamin B

12

group

and the difference was statistically significant（P

<

0.05）.The results of binary logistic regression analysis suggested that low vitamin B

12

level was an independent risk factor for poor prognosis in patients with lacunar cerebral infarction（OR=7.668;95% CI:1.201-48.974;P=0.031）.Conclusion Lowserum vitamin B

12

level is an independent risk factor for poor prognosis in acute lacunar cerebral infarction

probably because hypovitaminosis B

12

leads to subclinical abnormalities in cerebral white matter structures beyond the infarct sitewhich in turn leads to dysregulation of brain network compensation.Therefore

vitamin B

12

supplementation for patients with acute lacunar cerebral infarction has the potential to improve patient outcomes.However

this needs to be confirmed by increasing the sample size of the study and doing brain network studies at a later stage.