In this week's clinical case, Dr. Mike Bradshaw (Chicago Medical School and Billings Clinic) walks us through the case of a young woman with HSV encephalitis. With a twist. SPOILER ALERT: If you don't want to know the answer, DON'T LOOK AT THE SHOWNOTES! Produced by James E. Siegler and Mike Bradshaw. Music courtesy of Yan Terrien, Unheard Music Concepts, Steve Combs, and Montplaisir. Sound effects by Mike Koenig and Daniel Simion. BrainWaves' podcasts and online content are intended for medical education only and should not be used for clinical decision making. Be sure to follow us on Twitter @brainwavesaudio for the latest updates to the podcast. REFERENCES Bacon TH, Boon RJ, Schultz M and Hodges-Savola C. Surveillance for antiviral-agent-resistant herpes simplex virus in the general population with recurrent herpes labialis. Antimicrob Agents Chemother. 2002;46:3042-4. Granerod J, Ambrose HE, Davies NW, Clewley JP, Walsh AL, Morgan D, Cunningham R, Zuckerman M, Mutton KJ, Solomon T, Ward KN, Lunn MP, Irani SR, Vincent A, Brown DW, Crowcroft NS and Group UKHPAAoES. Causes of encephalitis and differences in their clinical presentations in England: a multicentre, population-based prospective study. Lancet Infect Dis. 2010;10:835-44. Steiner I, Budka H, Chaudhuri A, Koskiniemi M, Sainio K, Salonen O and Kennedy PG. Viral meningoencephalitis: a review of diagnostic methods and guidelines for management. European journal of neurology : the official journal of the European Federation of Neurological Societies. 2010;17:999-e57. Gable MS, Sheriff H, Dalmau J, Tilley DH and Glaser CA. The frequency of autoimmune N-methyl-D-aspartate receptor encephalitis surpasses that of individual viral etiologies in young individuals enrolled in the California Encephalitis Project. Clin Infect Dis. 2012;54:899-904. Pruss H, Finke C, Holtje M, Hofmann J, Klingbeil C, Probst C, Borowski K, Ahnert-Hilger G, Harms L, Schwab JM, Ploner CJ, Komorowski L, Stoecker W, Dalmau J and Wandinger KP. N-methyl-D-aspartate receptor antibodies in herpes simplex encephalitis. Annals of neurology. 2012;72:902-11. Armangue T, Leypoldt F and Dalmau J. Autoimmune encephalitis as differential diagnosis of infectious encephalitis. Curr Opin Neurol. 2014;27:361-8. Armangue T, Leypoldt F, Malaga I, Raspall-Chaure M, Marti I, Nichter C, Pugh J, Vicente-Rasoamalala M, Lafuente-Hidalgo M, Macaya A, Ke M, Titulaer MJ, Hoftberger R, Sheriff H, Glaser C and Dalmau J. Herpes simplex virus encephalitis is a trigger of brain autoimmunity. Annals of neurology. 2014;75:317-23. Venkatesan A and Benavides DR. Autoimmune encephalitis and its relation to infection. Current neurology and neuroscience reports. 2015;15:3. Linnoila JJ, Binnicker MJ, Majed M, Klein CJ and McKeon A. CSF herpes virus and autoantibody profiles in the evaluation of encephalitis. Neurol Neuroimmunol Neuroinflamm. 2016;3:e245. Armangue T, Spatola M, Vlagea A, Mattozzi S, Carceles-Cordon M, Martinez-Heras E, Llufriu S, Muchart J, Erro ME, Abraira L, Moris G, Monros-Gimenez L, Corral-Corral I, Montejo C, Toledo M, Bataller L, Secondi G, Arino H, Martinez-Hernandez E, Juan M, Marcos MA, Alsina L, Saiz A, Rosenfeld MR, Graus F, Dalmau J and Spanish Herpes Simplex Encephalitis Study G. Frequency, symptoms, risk factors, and outcomes of autoimmune encephalitis after herpes simplex encephalitis: a prospective observational study and retrospective analysis. The Lancet Neurology. 2018;17:760-772. Dubey D, Pittock SJ, Kelly CR, McKeon A, Lopez-Chiriboga AS, Lennon VA, Gadoth A, Smith CY, Bryant SC, Klein CJ, Aksamit AJ, Toledano M, Boeve BF, Tillema JM and Flanagan EP. Autoimmune encephalitis epidemiology and a comparison to infectious encephalitis. Annals of neurology. 2018;83:166-177.