Electroencephalographic abnormalities in aseptic meningitis and noninfectious headache. A comparative study

Area of Science:

• Neurology
• Infectious Diseases

Background:

• Electroencephalogram (EEG) abnormalities in aseptic meningitis are often presumed to indicate brain parenchymal involvement.
• This assumption persists even without clinical signs of encephalitis.

Purpose of the Study:

• To determine if aseptic nonherpetic meningitis patients with abnormal EEGs differ clinically or in cerebrospinal fluid findings from those with normal EEGs.
• To investigate the significance of EEG abnormalities in aseptic meningitis.

Main Methods:

• Reviewed EEG records of 82 patients with aseptic meningitis.
• Compared EEG findings with a control group of 41 age-matched patients with severe headaches but no meningeal inflammation.

Main Results:

• Aseptic meningitis patients showed significantly more EEG abnormalities (28%) than controls (12%).
• Patients with aseptic meningitis and abnormal EEGs did not differ in clinical or CSF findings from those with normal EEGs.
• Confusion in aseptic meningitis patients strongly correlated with EEG abnormalities (P<.00012).
• Common migraine patients also showed a trend towards more frequent EEG abnormalities.

Conclusions:

• Abnormal EEGs in aseptic meningitis patients with normal mental status and no focal neurological signs should not be considered definitive proof of encephalitis.
• The exact cause of EEG abnormalities in aseptic meningitis remains unclear, potentially indicating silent inflammation or infectious encephalopathy.