Fever is sometimes absent, and meningismus occurs in 50% of patients.

We bend their necks, looking for meningismus, the tell-tale rigidity.

Headache and meningismus are often signs of inflammation relayed via trigeminal sensory nerve fibers within the pia mater.

Young infants commonly require lumbar puncture as a part of the routine workup for fever without a source, as they have a much higher risk of meningitis than older persons and do not reliably show signs of meningeal irritation (meningismus).