Differential Diagnosis
- Single most likely diagnosis
- Viral infection (G): The patient's presentation with fever, emotional lability, and an episode of arm shaking, followed by somnolence and disorientation, suggests a viral encephalitis. The cerebrospinal fluid (CSF) analysis showing a lymphocytic predominance, elevated protein, and normal glucose levels further supports this diagnosis.
- Other Likely diagnoses
- Bacterial infection (A): Although less likely given the CSF lymphocytic predominance, bacterial meningitis cannot be entirely ruled out, especially with the presence of fever and altered mental status. However, the absence of a significantly elevated neutrophil count in the CSF makes this less probable.
- Hemorrhage (D): The presence of erythrocytes in the CSF could suggest a hemorrhagic component, possibly indicating a hemorrhagic stroke or a traumatic injury. However, the clinical context and the rest of the CSF analysis do not strongly support this as the primary diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Bacterial infection (A): Despite being less likely based on the CSF profile, bacterial meningitis is a medical emergency that requires prompt treatment. Missing this diagnosis could be fatal.
- Hemorrhage (D): Given the potential for rapid deterioration and the need for immediate intervention, hemorrhage must be considered and ruled out with appropriate imaging studies.
- Rare diagnoses
- Fungal infection (C): Fungal infections of the central nervous system are rare in immunocompetent hosts and would be an unusual cause of this patient's presentation.
- Parasitic infection (F): Parasitic infections affecting the CNS, such as neurocysticercosis or cerebral malaria, are rare in this clinical context and geographic location (assuming a typical Western setting).
- Congenital malformation (B): While congenital malformations can present with seizures or neurological deficits, they are less likely to present acutely with fever and the specific CSF findings described.
- Immune-mediated demyelination (E): Conditions like acute disseminated encephalomyelitis (ADEM) could present with altered mental status and neurological findings, but the presence of fever and the specific CSF profile makes this less likely in this acute setting.