The classic presentation of acute bacterial meningitis is headache, fever, neck stiffness and altered mental status, although only 44-66% of patients will present with each of these symptoms.
However, virtually all patients (99 to 100 percent) have at least one of the tetrad of symptoms (Attia et al., 1999) and nearly all patients have at least two symptoms. Complete absence of fever, stiff neck, altered mental status, and headache makes a diagnosis of bacterial meningitis very unlikely (van de Beek et al, 2004).
In three large trials of adults with meningitis, fever was present in 77 to 85 percent, neck stiffness in 83 to 94 percent, headache in 79 to 94 percent, and altered mental status in 83 percent, including coma in 14 to 16 percent (de Gans and van de Beek, 2002; van de Beek et al, 2004; Aronin et al, 1998).
However, no isolated finding is diagnostic, and the most accurate combination of signs and symptoms to aid diagnosis is unclear (Curtis et al, 2010)