Arthrocentesis, 1362 , 1364 –1365 Arthroscopic surgery, 1375 Artificial pulmonary surfactant, 67 Ascending reticular activating system (ARAS), 117 Asenapine, for schizophrenia, 1442 Askin tumor, 910 Ask Suicide Screening Questions (ASQ), 1446 Asparaginase, 926 Aspergillus infection, 444 , 998 Asphyxia, traumatic, 1287 Aspiration pneumonia, 943 –944 Aspirin (acetylsalicylic acid), 215 , 311 Assisted ventilation, 49 Asteatotic eczema, 433 , 433 f Asthma, 480 , 572 , 940 –942 Asymmetric chest wall movement/expansion, 486 Asymptomatic neutropenia, 786 Ataxia, 119 , 301 , 891 , 896 acute disseminated encephalomyelitis (ADEM) and, 107 acute postinfectious cerebellar, 107 appendicular, 107 common causes of, 107 , 108 t definition, 107 diagnosis of, 107 diagnostic pathway, 109 f differential diagnosis, 107 –108 , 108 t gait, 107 Guillain–Barré syndrome and, 108 , 108 t imaging and laboratory tests, 107 –108 ipsilateral limb, 107 from lesions outside of cerebellum, 107 management of, 109 stroke and, 108 symptoms and signs related to, 107 from toxic ingestions, 108 , 108 t truncal, 107 Atlantoaxial dislocations, 557