Diagnosis starts by examining the patient's symptoms. Symptoms can vary. Symptoms can include headache, sensitivity to light, neck stiffness, nausea, and vomiting. In some patients, fever is absent. Neurological examination and MRI can be normal.<unk>  is suspected based on symptoms, and can be confirmed by HSV 1 or HSV 2 on PCR of Cerebrospinal fluid (CSF), although not all cases test positive on PCR. PCR is performed on spinal fluid or blood, however, the viruses do not need to enter the spinal fluid or blood to spread within the body: they can spread by moving through the axons and dendrites of the nerves. During the first 24 h of the disease the spinal fluid will show predominant polymorphonuclear neutrophils and large cells that have been called endothelial<unk> 's) cells. A study performed on patients who had diffuse symptoms, such as persistent or intermittent headaches, concluded that although PCR is a highly sensitive method for detection, it may not always be sensitive enough for identification of viral DNA in CSF, due to the fact that viral shedding from latent infection may be very low. The concentration of viruses in CSF during subclinical infection might be very low. Investigations include blood tests (electrolytes, liver and kidney function, inflammatory markers and a complete blood count) and usually X-ray examination of the chest. The most important test in identifying or ruling out meningitis is analysis of the cerebrospinal fluid (fluid that envelops the brain and the spinal cord) through lumbar puncture (LP). However, if the patient is at risk for a cerebral mass lesion or elevated intracranial pressure (recent head injury, a known immune system problem, localizing neurological signs, or evidence on examination of a raised ICP), a lumbar puncture may be contraindicated because of the possibility of fatal brain herniation. In such cases, a CT or MRI scan is generally performed prior to the lumbar puncture to exclude this possibility. Otherwise, the CT or MRI should be performed after the LP, with MRI preferred over CT due to its superiority in demonstrating areas of cerebral edema, ischemia, and meningeal inflammation. During the lumbar puncture procedure, the opening pressure is measured. A pressure of over 180 mm H2O is suggestive of bacterial meningitis. It is likely that<unk>  meningitis is underrecognized by physicians, and improved recognition may limit unwarranted antibiotic use and shorten or eliminate unnecessary hospital admission. This shows the results of polymerase chain reaction tests on a chronic<unk>  patient, along with symptoms. PCR testing has advanced the state of the art in research, but PCR can be negative in individuals with<unk> 's, even during episodes with severe symptoms. For example, Kojima et al. published a case study for an individual who was hospitalized repeatedly, and who had clinical symptoms including genital herpes lesions. However, the patient was sometimes negative for HSV-2 by PCR, even though his meningitis symptoms were severe. Treatment with acyclovir was successful, indicating that a herpes virus was the cause of his symptoms.
Mollaret's meningitis
Rasmussen's encephalitis
La Crosse encephalitis
Fungal meningitis
Brain fever
Japanese encephalitis
Eastern equine encephalitis
Sappinia amoebic encephalitis