Which combination best defines typical diagnosis and main treatment of herpes simplex encephalitis?

Which combination best defines typical diagnosis and main treatment of herpes simplex encephalitis?

• A. MRI normal; CSF culture positive; treated with broad-spectrum antibiotics.
• B. MRI shows temporal lobe involvement; CSF PCR positive for HSV DNA; treated with acyclovir promptly.
• C. MRI shows occipital involvement; CSF HSV PCR negative; treated with steroids.
• D. MRI shows frontal involvement; CSF positive for HSV culture; treated with valganciclovir.

Answer: (B)

The key idea is that herpes simplex encephalitis is best identified by a classic pattern on imaging, a sensitive CSF test, and urgent antiviral treatment. Temporal lobe involvement on MRI is characteristic because HSV-1 preferentially affects the limbic system, producing focal neurologic signs and seizures. Detecting HSV DNA in CSF by PCR is the most reliable test and confirms the diagnosis, guiding targeted therapy. Because delays worsen outcomes, acyclovir is started promptly as soon as HSV encephalitis is suspected, even before PCR results are back. Broad-spectrum antibiotics won’t treat a viral infection, steroids aren’t the standard initial therapy, and HSV culture is far less sensitive than PCR; together, these facts explain why the combination of temporal lobe MRI findings, CSF HSV DNA by PCR, and immediate acyclovir treatment is the best answer.

The key idea is that herpes simplex encephalitis is best identified by a classic pattern on imaging, a sensitive CSF test, and urgent antiviral treatment. Temporal lobe involvement on MRI is characteristic because HSV-1 preferentially affects the limbic system, producing focal neurologic signs and seizures. Detecting HSV DNA in CSF by PCR is the most reliable test and confirms the diagnosis, guiding targeted therapy. Because delays worsen outcomes, acyclovir is started promptly as soon as HSV encephalitis is suspected, even before PCR results are back. Broad-spectrum antibiotics won’t treat a viral infection, steroids aren’t the standard initial therapy, and HSV culture is far less sensitive than PCR; together, these facts explain why the combination of temporal lobe MRI findings, CSF HSV DNA by PCR, and immediate acyclovir treatment is the best answer.