What is the common presenting symptom of HSV meningitis?

Severe headache is indeed the most common presenting symptom of herpes simplex virus (HSV) meningitis. This type of viral meningitis typically manifests with signs consistent with meningeal irritation, and headache is a hallmark symptom due to inflammation of the meninges surrounding the central nervous system. The headache associated with HSV meningitis can be intense and is often described as being different in character from other types of headaches a patient may have experienced.

While confusion, rash, and severe abdominal pain can occur in various medical conditions, they are not core or defining symptoms specifically linked to HSV meningitis. Confusion may appear in some cases but is less typical as a presenting symptom. A rash could occur due to herpes infection, but it's not consistent or common in viral meningitis cases. Severe abdominal pain is more characteristic of gastrointestinal conditions rather than neurological infections like meningitis. Thus, the presence of a severe headache is a more distinct and frequent indicator of HSV meningitis compared to the other options listed.