The mechanism of hemorrhagic complication in HSV encephalitis is unclear. The possible mechanisms include small vessel rupture due to vasculitis and transient hypertension caused by increased intracranial pressure. Gyral pattern of the hemorrhage may suggest that the hemorrhagic complication in HSV encephalitis may be due to associated vasculitis
Takeuchi, S., & Takasato, Y. (n.d.). Herpes simplex virus encephalitis complicated by intracerebral hematoma. Neurology India., 59(4), 594-596.
Herpes simplex virus (HSV) encephalitis is the most common cause of sporadic encephalitis, with a mortality of 70% if untreated. Treatment with acyclovir is associated with reduced mortality. Petechial cortical hemorrhages are common in HSV encephalitis, whereas frank hematoma is extremely rare; only 10 cases have been reported in the literature.
Intracerebral hematoma can complicate HSE even when the evolution is favorable. It should be suspected whenever neurologic deterioration appears and should be distinguished from acyclovir resistance and toxicity, since the management of these entities differs substantially.
Rodríguez-Sainz, A., Escalza-Cortina, I., Guio-Carrión, L., Matute-Nieves, A., Gómez-Beldarrain, M., Carbayo-Lozano, G., & Garcia-Monco, J. (2013). Intracerebral hematoma complicating herpes simplex encephalitis. Clinical Neurology and Neurosurgery, 115(10), 2041-2045.
Intracranial bleeding, although infrequent, can complicate the evolution of herpes simplex encephalitis and should be borne in mind since its presence may require neurosurgery. Although its presentation may overlap the encephalitic features, the lack of improvement or the worsening of initial symptoms, particularly during the second week of admission, should lead to this suspicion and to perform a neuroimaging study.
HSV enters the brain through the direct neuronal transmission from the peripheral site to the brain through the trigeminal or olfactory nerve. The usual manifestation of HSE is fever, headache, seizures, and change in mental status evolving over several days. Atypical manifestation includes intracerebral hemorrhage which has been reported mainly in infants and young children. Intracerebral hematoma in HSE in adults is rare. There are some reports of the occurrence of hematoma in HSE in the adults. The exact mechanism of hemorrhage in HSE is unclear. Vasculitis causing small vessel rupture and transient hypertension due to raised intracranial pressure has been proposed for hemorrhage in HSE.
Mahale, R., Mehta, A., Shankar, A., Miryala, A., Acharya, P., & Srinivasa, R. (2016). Bilateral Cerebral Hemorrhage in Herpes Simplex Encephalitis: Rare Occurrence. Journal of Neurosciences in Rural Practice., 7(Suppl 1), S128-S130.
The most frequent cause of sporadic encephalitis is herpes simplex encephalitis (HSE). It carries a mortality of 70% if left untreated. With the usage of acyclovir in the management of HSE and early diagnosis, the mortality rate has been reduced to 19%. Herpes simplex virus (HSV) causes hemorrhagic necrotizing encephalitis involving the frontal and medial temporal lobes. Petechial cortical hemorrhages have been reported in HSE; however, frank hematoma is rare.