Differential Diagnosis
The patient's presentation with fever, headache, and a history of a mechanical aortic valve suggests an infectious or thromboembolic complication. The presence of a systolic ejection murmur and mild left hemiparesis with Babinski's sign indicates possible involvement of the central nervous system (CNS) or the valve itself.
Single most likely diagnosis
- Infective Endocarditis: This is the most likely diagnosis given the patient's history of a mechanical aortic valve, fever, and new neurological findings. Infective endocarditis can lead to embolic events, which could explain the hemiparesis and Babinski's sign.
Other Likely diagnoses
- Septic Embolism: A possible complication of infective endocarditis, where septic emboli could cause CNS symptoms, including the observed hemiparesis.
- Cerebral Embolism: Given the mechanical valve and the presence of a murmur, there's a risk of thromboembolic events leading to cerebral embolism, which could cause the neurological deficits.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Brain Abscess (A): Although less common, brain abscesses can occur as a complication of infective endocarditis, especially if the infection is caused by certain bacteria. The absence of nuchal rigidity does not rule out this diagnosis.
- Venous Sinus Thrombosis (E): This could be a complication of the hypercoagulable state sometimes associated with infections or the mechanical valve itself, though it's less directly related to the valve infection.
Rare diagnoses
- Carotid Artery Occlusion (B): While possible, this would be less directly related to the patient's valve and more related to atherosclerotic disease or other causes of carotid occlusion.
- Encephalitis (C): Direct infection of the brain tissue could present with fever and neurological signs, but it's less likely given the context of a mechanical valve and the specific neurological findings.
- Hydrocephalus (D): This could be a complication of various CNS infections or hemorrhages but is less directly linked to the patient's presentation and history of a mechanical valve.