Brain Dysfunction
After a Hard Hike?
The initial assessment at Dr. Miller’s office reveals that Mercedes has a fever (101°F), tremor in the right hand, and weakness in both legs and that she is disoriented. A sample of cerebrospinal fluid (CSF) is collected; white blood cell count is elevated, glucose is normal, and protein is elevated. Bacterial and viral analysis of the CSF is negative. Upon his initial assessment, Dr. Miller admits Mercedes to the hospital for monitoring. Her condition has continued to worsen. An electroencephalogram (a test of brain activity) reveals mild encephalopathy (disease or disorder of the brain). Eight days after her admission to the hospital, serological analysis of CSF from Mercedes indicates a positive result for West Nile Virus (WNV)–specific IgM. There is no specif ic treatment for WNV. Mercedes remains in the hospital, where she receives supportive care and careful monitoring for intracranial pressure and seizures. Three weeks later, Mercedes is released from the hospital with some residual weakness in her right leg and no remaining mental alterations.
1. Why was Mercedes’s initial CSF sample negative for WNV–specific IgM?
2. Why must Mercedes be monitored for changes in intracranial pressure and seizure?
1. Mercedes's initial CSF sample was negative for WNV-specific IgM because it takes time for the body to produce antibodies in response to the infection. In the early stages of the infection, the body may not have produced sufficient levels of WNV-specific IgM antibodies to be detected in the CSF sample.
2. Mercedes must be monitored for changes in intracranial pressure and seizures because West Nile Virus can cause inflammation and damage to the brain. Increased intracranial pressure can be a result of inflammation and swelling in the brain, which can lead to detrimental effects if not managed properly. Seizures can also occur as a result of the infection's impact on the brain, and monitoring for them allows for prompt medical intervention if necessary.
1. Mercedes's initial CSF sample was negative for WNV-specific IgM because it takes time for the body to produce detectable levels of antibodies against the virus. IgM antibodies are typically detected in the blood or CSF around 8-10 days after infection. Therefore, her initial sample may have been collected before the antibodies had reached detectable levels.
2. Mercedes must be monitored for changes in intracranial pressure and seizures because these are potential complications of West Nile Virus (WNV) infection affecting the central nervous system. WNV can cause inflammation in the brain (encephalitis) or the lining surrounding the brain and spinal cord (meningitis), leading to increased pressure within the skull (intracranial pressure). Monitoring intracranial pressure helps to ensure that immediate intervention can be taken if pressure levels become dangerously high.
Seizures can also occur as a result of brain dysfunction and inflammation caused by the viral infection. Monitoring for seizures allows for timely recognition and appropriate management to prevent further complications.