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Is EEG useful in assessing patients with acute encephalitis treated with acyclovir?
J Sirén1, A M Seppäläinen, J Launes
1Department of Neurology, Helsinki University Hospital, Finland. jan.siren@pp.fimnet.fi
Electroencephalography and Clinical Neurophysiology
|January 1, 1999
Summary
Electroencephalography (EEG) can predict outcomes in encephalitis patients. Periodic complexes in acute EEG predict poor prognosis, while diffuse slowing at follow-up indicates a less favorable outcome.
Area of Science:
- Neurology
- Neurophysiology
Background:
- Electroencephalography (EEG) is crucial for diagnosing encephalitis, particularly herpes simplex virus encephalitis (HSVE).
- Previous understanding of EEG prognostic value in encephalitis may be influenced by the pre-acyclovir era.
Purpose of the Study:
- To analyze the prognostic value of EEG findings in acyclovir-treated patients with acute encephalitis.
- To determine the correlation between specific EEG abnormalities and patient outcomes.
Main Methods:
- Analysis of 204 EEG recordings from 98 acyclovir-treated acute encephalitis patients (1984-1994).
- Evaluation of periodic complexes and diffuse slowing of background activity as prognostic indicators.
- Correlation of EEG findings with clinical variables and patient outcomes.
Main Results:
- Periodic complexes during the acute phase significantly predicted a poor outcome (Kendall tau 0.40, P < 0.001).
- Diffuse slowing of background activity in the acute phase did not predict outcome (Kendall tau -0.6, P = 0.35).
- Emergence of diffuse slow background activity at follow-up was associated with a less favorable outcome (Kendall tau 0.33, P = 0.0016).
- Early epileptic seizures were the only clinical variable significantly correlating with outcome.
Conclusions:
- EEG is a valuable prognostic tool in acute encephalitis, especially in the context of acyclovir treatment.
- The significance of acute-phase diffuse slowing and irritative EEG features for prognosis appears less critical than previously assumed.
- Prognostic interpretation of EEG in encephalitis requires consideration of treatment era and specific EEG patterns like periodic complexes and later-emerging diffuse slowing.