Additional testing, such as serology for various arboviruses and HIV testing, may also be performed based on the individuals history and symptoms. Brain biopsy and body fluid specimen cultures and PCR may also be useful in some cases. Electroencephalography (EEG) is abnormal in more than 80% of viral encephalitis cases, including those who are experiencing seizures, and may need to be monitored continuously to identify non-convulsive status. Lack of testing resources may prevent accurate diagnosis.Test results specific to certain viruses include:
For herpes simplex virus encephalitis, a CT scan may show low-density lesions in the temporal lobe. These lesions usually appear 3 to 5 days after the start of the infection. Japanese encephalitis often has distinct EEG patterns, including diffuse delta activity with spikes, diffuse continuous delta activity, and alpha coma activity. Differential diagnosis
A broad differential diagnosis can be performed that looks at many potential causes of the encephalitis, infectious and noninfectious. Potential alternatives to viral encephalitis include malignancy, autoimmune or paraneoplastic diseases such as anti-NMDA receptor encephalitis, a brain abscess, tuberculosis or drug-induced delirium, exposure to certain drugs or toxins, neurosyphilis, vascular disease, metabolic disease, or encephalitis from infection caused by a bacterium, fungus, protozoan, or parasitic worm. In children, differential diagnosis may not be able to distinguish between viral encephalitis and immune-mediated inflammatory CNS diseases, such as acute disseminated encephalomyelitis, as well as immune-mediated encephalitis, so other diagnostic methods may need to be used.
However, genetic and family studies have demonstrated that the presence of Darwins tubercle may be more likely to be influenced by ones environment or developmental accidents than it is by genetics alone. There is no clear argument for whether the trait has significance in sexual dimorphism studies or age related studies. In some studies, there is clear data that Darwins tubercle is not associated with sex. In contrast, others indicate that there is a correlation with sexual dimorphism between men and women, where men tend to have the tubercle more than women in some populations. Two studies indicate that older men tend to have greater expression of Darwins tubercle than do older women. See also
Human vestigiality

References


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