RT Book, Section A1 Hay, Jr, William W. A1 Levin, Myron J. A1 Deterding, Robin R. A1 Abzug, Mark J. SR Print(0) ID 1145456210 T1 Horner Syndrome T2 Quick Medical Diagnosis & Treatment Pediatrics YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9781264257614 LK accesspediatrics.mhmedical.com/content.aspx?aid=1145456210 RD 2024/09/08 AB Caused by an abnormality or lesion to the sympathetic chainCongenital variety is most commonly the result of birth traumaAcquired cases may occur in children who have had cardiothoracic surgery, trauma, neoplasm, or brainstem vascular malformationMost worrisome cause is neuroblastoma of the sympathetic chain in the apical lung region