ABSTRACT: Importance:Preventing delayed neurological sequelae is a major goal of treating acute carbon monoxide poisoning, but to our knowledge there are no reliable tools for assessing the probability of these sequelae. Objectives:To determine whether acute brain lesions on diffusion-weighted imaging are related to subsequent development of delayed neurological sequelae after acute carbon monoxide poisoning. Design, Setting, and Participants:This registry-based observational study was conducted at a university hospital in Seoul, Korea, between April 1, 2011, and December 31, 2015. Of 700 patients (aged ?18 years) with acute carbon monoxide poisoning, 433 patients (61.9%) who underwent diffusion-weighted imaging at an emergency department were considered for the study. Patients who developed cardiac arrest before diffusion-weighted imaging (n?=?3), had persistent neurological symptoms at discharge (n?=?8), committed suicide soon after discharge (n?=?1), and were lost to follow-up (n?=?34) were excluded. Exposure:The presence of unambiguous, high-signal-intensity, acute brain lesions on diffusion-weighted imaging (b?=?1000 s/mm2). Main Outcomes and Measures:Development of delayed neurological sequelae defined as any neurological symptoms or signs that newly developed within 6 weeks of discharge. Results:Of the 387 included patients (143 women [37.0%]; median age, 42.0 years [interquartile range, 32.0-56.0 years]), acute brain lesions on diffusion-weighted imaging were observed in 104 patients (26.9%). Among these, 77 patients (19.9%) had globus pallidus lesions, 13 (3.4%) had diffuse lesions, and 57 (14.7%) had focal lesions (37 patients [9.6%] had >1 pattern concurrently). Lesions were supratentorial and infratentorial in 101 and 23 patients, respectively. Delayed neurological sequelae occurred in 101 patients (26.1%). Multivariable logistic regression analysis indicated that the presence of acute brain lesions was independently associated with development of delayed neurological sequelae (adjusted odds ratio, 13.93; 95% CI, 7.16-27.11; P?
