If a patient has signs and symptoms of encephalitis, or if other test results suggest encephalitis, encephalitis cannot be ruled out even if the cerebrospinal fluid test is normal.
Encephalitis is an inflammatory lesion of the brain caused by viral, bacterial, fungal, or parasitic infections, often accompanied by headache and fever. Cerebrospinal fluid (CSF) testing is the most common test used to determine encephalitis infection. In most cases, encephalitis is accompanied by abnormal CSF tests, but this does not mean that normal CSF can rule out encephalitis.
In the early stages of encephalitis and in some cases of viral encephalitis, the cerebrospinal fluid may not always be abnormal. If the patient’s symptoms and signs, as well as the results of other tests such as cerebral magnetic resonance imaging (MRI), still give rise to a high suspicion of encephalitis, further investigations are needed to make a definitive diagnosis.
It is recommended that the patient go to a regular hospital for a clear diagnosis and active treatment under the guidance of a doctor.