Encephalitis Diagnosis and Treatment in the Elderly

Epidemiology and Risk Factors

The American Academy of Neurology suggests that herpes simplex virus (HSV) encephalitis is the most common cause of encephalitis in women over 80 years, with a higher risk of mortality and requiring urgent treatment with aciclovir 1, 2
The Infectious Diseases Society of America notes that HSV shows a bimodal distribution with peaks of incidence in young children and the elderly, especially those over 60 years, with HSV-1 responsible for 90-98% of cases in adults 1, 2, 3
The Centers for Disease Control and Prevention (CDC) indicates that encephalitis due to HSV is more common in the elderly than in young adults, with a significantly higher risk of mortality in patients over 63 years 1, 2, 3

The American College of Physicians recommends that the diagnosis of encephalitis in the elderly is especially challenging because they are more likely to present with other causes of neurological disorders, such as stroke, and systemic causes of brain dysfunction, such as sepsis 1, 2
The European Society of Clinical Microbiology and Infectious Diseases suggests that the reactivation of varicella-zoster virus (VZV) can cause encephalitis, especially in the elderly, with a typically insidious onset 1, 2
The National Institute of Neurological Disorders and Stroke (NINDS) notes that autoimmune encephalitis mediated by antibodies has a median age of presentation of 65 years, with a male predominance of 2:1 4

The Infectious Diseases Society of America recommends that a lumbar puncture should be performed as soon as possible after hospital admission, unless there is a clinical contraindication 1, 2
The American Academy of Neurology suggests that if there is a contraindication due to suspected increased intracranial pressure, an urgent CT scan should be performed before the lumbar puncture 1, 2
The Centers for Disease Control and Prevention (CDC) indicates that empirical aciclovir treatment should be initiated immediately without waiting for test results, as delayed treatment is associated with a worse prognosis 3

The American College of Physicians recommends that aciclovir should be started immediately in cases of suspected HSV encephalitis, as mortality without treatment is 70% but is reduced to 25-28% with early treatment 3
The European Society of Clinical Microbiology and Infectious Diseases suggests that immunotherapy should be initiated as soon as possible in cases of autoimmune encephalitis, without waiting for confirmation of antibodies 5
The National Institute of Neurological Disorders and Stroke (NINDS) notes that delayed treatment more than 48 hours after hospital admission is associated with a worse prognosis 3