| What is a herpes infection ? Herpes infections are very frequent in the world population. It is usually benign but it can also manifest themselves in a serious or even fatal form exceptionally (Rozenberg, 2012). More exactly, the role of the Herpes simplex virus in central nervous system infections was established in 1941 (Rozenberg, 2012). This virus has been classified into two sub-groups : Herpes simplex virus 1 (HSV-1) which usually infects the mouth or lips but also Herpes simplex virus 2 (HSV-2) which is sexually transmitted and usually infects the genital region (Rozenberg, 2012). The virus is most often asymptomatic, which results in people who have the virus being unaware of their infection. When the virus manifests, it causes small, painful, fluid-filled blisters on the skin, mouth, lips or genitals, depending on the type of virus. And it is at this time, when the vesicles are present, that the contagiousness is the greatest. It is important to know that HSV-1 and HSV-2 infections are lifelong and are characterized by the establishment of a viral latency maintained throughout the life of the infected person. What is herpes encephalitis ? Herpes encephalitis is a rare but potentially complication of herpes infections. It is characterized by a brain infection most commonly by the Herpes simplex virus 1 (HSV-1) (Rozenberg, 2012). It is possible that Herpes simplex virus 2 (HSV-2) causes herpes encephalitis in rare cases. It has an annual incidence of 2 to 4 cases per million inhabitants in the world and this incidence is higher in children under 3 years of age or in adults over 50 years of age (Esposito et al., 2022). Generally, herpes encephalitis presents as a necrotizing encephalitis occurring in particular in the frontal and temporal lobes but also in the insular cortex of cerebral hemispheres (Esposito et al., 2022). The clinical manifestations occur within 48 hours and the onset of these symptoms is similar to any other form of acute encephalitis. During the prodromal phase, it is characterized by fever, headache, otolaryngologist and digestive signs. Then, it is possible that behavioral, memory and language disorders occur during the state phase. The patient may also suffer from disorders of consciousness leading to an obnubilation which may precede the coma (Rozenberg, 2012). How to diagnose herpes encephalitis ? In addition to clinical manifestations, imaging studies and analysis of the cerebrospinal fluid are important for diagnosis (Patoulias et al., 2017). In the first place, a lumbar puncture is executed to look for a potential increase in lymphocytes in the cerebrospinal fluid and to confirm the presence of Herpes virus simplex (Rozenberg, 2012). The PCR HSV is also executed to look for fragments of viral DNA. However, it is possible to obtain false-negative results after the onset of clinical manifestations (Patoulias et al., 2017). Finally, MRI scan is executed because it is considered as the best way to demonstrate brain damage caused by Herpes simplex virus : the results generally show an asymmetry in the temporal and frontal lobes (Rozenberg, 2012). What are the cognitive disorders caused by herpes encephalitis ? A neuropsychological assessment allows us to refine the diagnosis and to specify the cognitive domains affected, in other words, to evaluate the deficiencies. A study was conducted by Harris et al. (2020) to identify cognitive impairment that may follow herpes encephalitis. Concerning the memory functions, patients with herpes encephalitis show impaired anterograde memory regarding visual and verbal recall and recognition. They also show impairment in retrograde memory (episodic and semantic), which varies between patients. According to a subjective assessment of the patients, they themselves reported significantly higher perceived fatigue, slower mental speed, and complaints of memory, concentration, and language impairment. Thus, there are also language difficulties and more specifically denomination disorders. On the executive level, there is an impairment of verbal fluency. In addition to cognitive problems, behavioral problems may also be present. First, patients may suffer from eating disorders such as anorexia and bulimia. There may also be mood disorders, apathy which corresponds to a loss of motivation, interest, desires and emotions ; a decrease in emotional reactions ; irritability and hyperemotivity. Patients may suffer from anxiety and depression too. There may also be disorders of vigilance and consciousness as well as comital disorders (related to epilepsy). Finally, spatial and temporal disorientation and hallucinations may occur. Treatments and care The evolution of herpetic encephalitis is serious: there is a 20 % mortality rate for those who are treated, and 90 % of surviving patients present with serious neurological sequelae. And if the encephalitis is not treated, the mortality is about 70 %, hence the importance and urgency of carrying out the care as soon as possible (McGrath et al., 1997). To reduce the mortality rate, pharmacological care has been introduced. This consists of an antiviral treatment, named Aciclovir, which inhibits viral replication and prevents the spread of the disease in the brain. There may also be psychological care to help patients if they suffer from depression and/or anxiety. It can permit them to have support after this ordeal. Furthermore, for language disorders, patients can have sessions with speech therapists. Generally, it is important to encourage a multidisciplinary approach that also includes the patient’s well-being and needs. Regarding neuropsychological remediation, cognitive compensation and rehabilitation are maybe the more adapted care knowing that the long-term consequences of cognitive complications are important. In fact, the resumption of pre-encephalitis activities can be very difficult: “Only a third or even half of patients are able to resume their previous professional or occupational activities” (Oerthel, 2019). In this case, cognitive compensation could be interesting because it focuses on the preserved functions that can be used to compensate for the cognitive deficit. For example, in cases of verbal episodic memory deficits, strategic techniques for generating mental images during encoding can be proposed to help build a more valuable memory trace. Then, accommodations can be made, knowing that “more than 10% of patients are recognized as disabled” (Oerthel, 2019). Thus, rehabilitation can be proposed in order to modify and adapt the patient’s environment in order to minimize the impact of his disorders. In practice, it is often done in collaboration with occupational therapists. For example, there may be the use of colored signs, or an agenda for patients with memory problems. Words we have learned : > contagiousness (contagiosité) > otolaryngologist (oto-rhino-laryngologique = ORL) > resumption (reprise) > spread (expansion/diffusion/propagation) > herpetic encephalitis (encéphalite herpétique) Bibliography : Esposito, S., Autore, G., Argentiero, A., Ramundo, G., & Principi, N. (2022). Autoimmune encephalitis after herpes simplex encephalitis : A still undefined condition. Autoimmunity Reviews, 21(12), 103187. https://doi.org/10.1016/j.autrev.2022.103187 Harris, L., Griem, J., Gummery, A., Marsh, L., Defres, S., Bhojak, M., Das, K., Easton, A., Solomon, T., & Kopelman, M. (2020). Neuropsychological and psychiatric outcomes in encephalitis : A multi-centre case-control study. PLoS ONE, 15(3), 1-24. https://doi.org/10.1371/journal.pone.0230436. Hasni Bouraoui, I., Hmila, L., Arifa, N., Hassaoun, S., Gamaoun, W., Jemni, H., Harbi, A., & Tlili Graiess, K. (2011). Méningo-encéphalite herpétique et encéphalomyélite aiguë disséminée : séquence en imagerie par résonance magnétique. Archives de Pédiatrie, 18(1), 58‑61. https://doi.org/10.1016/j.arcped.2010.10.009. McGrath, N., Anderson, N. E., Croxson, M. C., & Powell, K. F. (1997). Herpes simplex encephalitis treated with acyclovir : diagnosis and long term outcome. Journal of Neurology, Neurosurgery & ; Psychiatry, 63(3), 321‑326. https://doi.org/10.1136/jnnp.63.3.32. Oerthel, A. (2019). Description de l’évolution cognitive au décours d’une encéphalite infectieuse ou non infectieuse. [Thèse de doctorat, Université de Grenoble]. dumas.ccsd.cnrs.fr. Patoulias, D., Gavriiloglou, G., Kontotasios, K., Tzakri, M., Keryttopoulos, P., & Koutras, C. (2017). HSV-1 Encephalitis: High Index of Clinical Suspicion, Prompt Diagnosis, and Early Therapeutic Intervention Are the Triptych of Success – Report of Two Cases and Comprehensive Review of the Literature. Case Reports in Medecine, 1-6. doi: 10.1155/2017/5320839 Rozenberg, F. (2012). Données actuelles sur l’encéphalite herpétique. Revue Francophone des Laboratoires, 2012(447), 27‑31. https://doi.org/10.1016/s1773-035x(12)71776-8. Segondy, M. (2017). Atteintes du système nerveux central d’origine virale. Revue Francophone des Laboratoires, 2017(495), 47‑56. https://doi.org/10.1016/s1773-035x(17)30322-2. by Margot De Vergie, Carla Vantighem and Clotilde Sorin |