How are your meninges?

Today in morning report we discussed a case of a patient with fever, headache, and focal neurological signs. Those in the room were appropriately concerned about a CNS cause.
Could this patient have meningitis or something else (such as blood in subarachnoid hemorrhage) irritating his meninges?

Symptoms suggestive of meningeal irritation are: headache, neck stiffness, photophobia, cranial nerve palsies. These, in addition to fever/chills and other infectious symptoms can suggest a diagnosis of meningitis.

In meningitis, clinical history does a poor job of leading us to the diagnosis. Neck stiffness on history has a sensitivity of only 28%.

For physical exam, Kernig's and Brudzinski's signs have poor sensitivity and specificity (based on little data) for meningitis.

Jolt accentuation of headache is quite sensitive (97%) based on one study of 54 patients with fever and headache, making it a good ruling-out test if it is negative. To perform the test, ask the patient to shake their head from side-to-side at about 2-3Hz and ask them if their headache is better, the same or worse. If it is not worse, this significantly decreases the likelihood of meningitis.

It generates a positive likelihood ratio of 2.4 and negative likelihood ratio of 0.05 for CSF pleiocytosis (increased cell count). In order to use a likelihood ratio, you multiply the pre-test probability by the LR to get the post-test probability. See the image below for a visual of this calculation:

You can read more about this in the JAMA Rational Clinical Exam Article "Does This Patient Have Acute Meningitis" follow link here http://jama.jamanetwork.com/article.aspx?articleid=774331#JRC80004T4