Are electroencephalogram (EEG) results helpful in assessing brain function in a patient with Herpes Simplex Virus type 1 (HSV-1) Encephalitis?

From the Guidelines

EEG results are helpful in assessing brain function in patients with Herpes Simplex Virus type 1 (HSV-1) Encephalitis, as they can detect abnormal electrical activity, including periodic lateralized epileptiform discharges (PLEDs) and focal slowing, particularly in the temporal lobes. The use of EEG in evaluating brain function in patients with HSV-1 encephalitis is supported by several studies, including a 2012 guideline by the Association of British Neurologists and British Infection Association, which states that EEG is abnormal in most patients with encephalopathy, including more than 80% of those with acute viral encephalitis 1. Some key points to consider when using EEG in patients with HSV-1 encephalitis include:

• EEG can be helpful in distinguishing whether abnormal behavior is due to a primary psychiatric disease or acute encephalitis 1
• EEG is useful for identifying non-convulsive or subtle motor seizures, which occur in both HSV encephalitis and other encephalopathies 1
• EEG abnormalities in HSV encephalitis include non-specific diffuse high amplitude slow waves, sometimes with temporal lobe spike-and-wave activity and periodic lateralized epileptiform discharges (PLEDs) 1
• EEG findings should be interpreted alongside clinical presentation, CSF analysis, and neuroimaging, as they are not specific to HSV encephalitis alone 1
• Serial EEGs can help track treatment response and disease progression, and EEG remains an important tool in the diagnostic workup and management of patients with suspected HSV-1 encephalitis, particularly when seizures are a concern or when other diagnostic modalities are unavailable or inconclusive 1

From the Research

EEG Results in Assessing Brain Function

• EEG results can be helpful in assessing brain function in patients with Herpes Simplex Virus type 1 (HSV-1) Encephalitis, as they can detect subtle or subclinical disturbances of cerebral function and allow monitoring of cerebral activity over time 2.
• Certain EEG phenotypes, such as lateralised periodic discharges, may indicate a specific pathophysiology, including HSV-1 encephalitis 2, 3, 4.
• EEG can be used to monitor the progression of the disease in patients with treatment refractory HSE, and may prompt escalation in therapy 4.

Prognostic Value of EEG

• EEG findings, such as absence of reactivity to auditory/noxious stimuli, can be associated with poor functional outcome in adult patients with severe herpes simplex encephalitis 5.
• Lateralized periodic discharges, seizures, and status epilepticus can be recorded in patients with HSV-1 encephalitis, but their presence may not always be associated with poor outcome 3, 6, 5.
• The prognostic value of EEG can be influenced by various factors, including the timing of the EEG recording, the presence of sedation, and the clinical context of the patient 5.

Clinical Applications of EEG

• EEG can be used to confirm or exclude non-convulsive seizures or status epilepticus, particularly in critically ill patients 2.
• EEG can be included in specialist guidelines for disease assessment, monitoring, and prognostication of various types of encephalitis, including viral and autoimmune encephalitis 2.
• Continuous EEG monitoring can provide valuable information on the progression of the disease and the response to treatment in patients with HSE 4.