Molecular test using Polymerase Chain Reaction (PCR) technique to detect genetic material (DNA) of Herpes Simplex Virus type I (HSV-1) and/or type II (HSV-2) in Cerebrospinal Fluid (CSF). Considered the gold standard for diagnosing central nervous system herpes infections, such as herpes encephalitis or myelitis, due to its high sensitivity and specificity compared to culture.