Differential Diagnosis for a 2-year-old girl with lethargy and confusion
- Single most likely diagnosis
- Reye's syndrome: This condition is characterized by acute non-inflammatory encephalopathy and fatty degenerative liver disease, often associated with the use of aspirin during a viral infection. The patient's symptoms, such as lethargy, confusion, and liver dysfunction (elevated liver enzymes and ammonia), along with the recent history of a viral illness (fever and nasal discharge), make Reye's syndrome a strong consideration. The presence of diffuse cerebral edema on the CT scan also supports this diagnosis.
- Other Likely diagnoses
- Acute viral encephalitis: Given the patient's recent viral illness and the presence of cerebral edema, viral encephalitis is a possible diagnosis. The fact that the patient's older sister had a cold sore (likely caused by herpes simplex virus) increases the suspicion for herpes simplex encephalitis, although the absence of specific symptoms such as seizures or focal neurologic deficits makes this less likely.
- Metabolic disorders: The patient's low glucose level, elevated ammonia, and liver dysfunction could suggest a metabolic disorder, such as a urea cycle defect or organic acidemia. However, these conditions are less likely given the patient's age and the absence of other specific symptoms.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Herpes simplex encephalitis: Although less likely than Reye's syndrome, herpes simplex encephalitis is a medical emergency that requires prompt treatment with antiviral medication. The patient's exposure to a family member with a cold sore increases the risk, and missing this diagnosis could be fatal.
- Bacterial meningitis: Although the patient's neck is supple and there are no other specific symptoms of meningitis, this condition is a medical emergency that requires prompt treatment with antibiotics. The presence of cerebral edema and the patient's altered mental status make it essential to consider and rule out bacterial meningitis.
- Rare diagnoses
- Wilson's disease: This rare genetic disorder can cause liver dysfunction, neurologic symptoms, and psychiatric abnormalities. Although the patient's age and symptoms make this diagnosis less likely, it is essential to consider Wilson's disease in the differential diagnosis of liver dysfunction and neurologic abnormalities.
- Mitochondrial disorders: These rare genetic disorders can cause a range of symptoms, including liver dysfunction, neurologic abnormalities, and metabolic disturbances. Although less likely, mitochondrial disorders should be considered in the differential diagnosis, especially if other causes are ruled out.