title: Long-term outcome of severe herpes simplex encephalitis: a population-based observational study.
abstract: BACKGROUND
  Herpes simplex encephalitis (HSE) is a rare disease with a poor prognosis. No recent evaluation of hospital incidence, acute mortality and morbidity is available. In particular, decompressive craniectomy has rarely been proposed in cases of life-threatening HSE with temporal herniation, in the absence of evidence. This study aimed to assess the hospital incidence and mortality of HSE, and to evaluate the characteristics, management, the potential value of decompressive craniectomy and the outcome of patients with HSE admitted to intensive care units (ICUs).
  
  
  METHODS
  Epidemiological study: we used the hospital medical and administrative discharge database to identify hospital stays, deaths and ICU admissions relating to HSE in 39 hospitals, from 2010 to 2013. Retrospective monocentric cohort: all patients with HSE admitted to the ICU of the university hospital during the study were included. The use of decompressive craniectomy and long-term outcome were analyzed. The initial brain images were analyzed blind to outcome.
  
  
  RESULTS
  The hospital incidence of HSE was 1.2/100,000 inhabitants per year, 32 % of the patients were admitted to ICUs and 17 % were mechanically ventilated. Hospital mortality was 5.5 % overall, but was as high as 11.9 % in ICUs. In the monocentric cohort, 87 % of the patients were still alive after one year but half of them had moderate to severe disability. Three patients had a high intracranial pressure (ICP) with brain herniation and eventually underwent decompressive hemicraniectomy. The one-year outcome of these patients did not seem to be different from that of the other patients. It was not possible to predict brain herniation reliably from the initial brain images.
  
  
  CONCLUSIONS
  HSE appears to be more frequent than historically reported. The high incidence we observed probably reflects improvements in diagnostic performance (routine use of PCR). Mortality during the acute phase and long-term disability appear to be stable. High ICP and brain herniation are rare, but must be monitored carefully, as initial brain imaging is not useful for identifying high-risk patients. Decompressive craniectomy may be a useful salvage procedure in cases of intractable high ICP.
authors.affiliation: Service de Réanimation Polyvalente, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. youenn.jouan@gmail.com.|Faculté de médecine, Université François Rabelais, 10 boulevard Tonnellé, 37032, Tours, France. youenn.jouan@gmail.com.
authors.forename: Youenn
authors.initials: Y
authors.lastname: Jouan
authors.affiliation: Service d'information médicale, d'épidémiologie et d'économie de la santé, UREH, EE EES, Hôpital Bretonneau, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. leslie.guillon@univ-tours.fr.|Faculté de médecine, Université François Rabelais, 10 boulevard Tonnellé, 37032, Tours, France. leslie.guillon@univ-tours.fr.
authors.forename: Leslie
authors.initials: L
authors.lastname: Grammatico-Guillon
authors.affiliation: Faculté de médecine, Université François Rabelais, 10 boulevard Tonnellé, 37032, Tours, France. fabien.espitalier@univ-tours.fr.|Département d'Anesthésie & Réanimation, Hôpital Trousseau, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. fabien.espitalier@univ-tours.fr.
authors.forename: Fabien
authors.initials: F
authors.lastname: Espitalier
authors.affiliation: Service de Neuroradiologie, Hôpital Bretonneau, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. cazalsxavier@hotmail.com.
authors.forename: Xavier
authors.initials: X
authors.lastname: Cazals
authors.affiliation: Faculté de médecine, Université François Rabelais, 10 boulevard Tonnellé, 37032, Tours, France. patrick.francois@univ-tours.fr.|Service de Neurochirurgie, Hôpital Bretonneau, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. patrick.francois@univ-tours.fr.
authors.forename: Patrick
authors.initials: P
authors.lastname: François
authors.affiliation: Service de Réanimation Polyvalente, CHRU Tours, 2 boulevard Tonnellé, 37000, Tours, France. antoine.guillon@univ-tours.fr.|Faculté de médecine, Université François Rabelais, 10 boulevard Tonnellé, 37032, Tours, France. antoine.guillon@univ-tours.fr.
authors.forename: Antoine
authors.initials: A
authors.lastname: Guillon
mesh_terms: D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000150:complications / Q000209:etiology / Q000401:mortality; D020803:Encephalitis, Herpes Simplex / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D015601:Injury Severity Score; D019586:Intracranial Hypertension / Q000209:etiology / Q000401:mortality; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D011379:Prognosis; D012189:Retrospective Studies; D016896:Treatment Outcome