Diagnosis of Meningitis
A diagnosis of meningitis depends primarily on a thorough physical examination and cerebrospinal fluid (CSF) analysis.
In the physical examination stiff neck, severe headache, and fever indicate meningitis. It may be extremely painful to move the neck forward. The neck may be so stiff that attempting to move it causes the entire body to move. Other signs the physician may look for include swelling in the eyes, which indicates elevated intracranial pressure, and skin rash.
Computed tomography (CT scan) or magnetic resonance imaging (MRI scan) of the brain may be used to evaluate possible swelling (edema) and bleeding (hemorrhage) and to rule out other neurological disorders.
Laboratory tests that may be performed include complete blood count (CBC), blood culture, and spinal tap. CBC will show elevated levels of white blood cells if there is an active infection in the body. Blood is cultured to identify bacteria in the blood.
Spinal tap, or lumbar puncture, is essential in diagnosing and selecting appropriate treatment for meningitis. About 2 tablespoons of cerebrospinal fluid is drawn into a needle inserted between two lumbar vertebrae. Lab analysis looks for elevated levels of white blood cells and blood. The fluid also is cultured to identify the organism causing meningitis.