Differential Diagnosis for Dizziness in a Patient with Bacterial Endocarditis

• Single most likely diagnosis
  • Gentamicin ototoxicity: Although the patient's hearing is not affected, gentamicin ototoxicity can also cause vestibular toxicity, leading to dizziness and unsteadiness without affecting hearing. The patient's symptoms of persistent dizziness and unsteadiness, even in the absence of hearing loss, make this a likely cause, especially given the use of gentamicin.
• Other Likely diagnoses
  • Cerebral embolism: Bacterial endocarditis increases the risk of embolic events, including cerebral embolism, which can cause a variety of neurological symptoms, including dizziness. However, the absence of specific neurological signs makes this less likely than gentamicin ototoxicity.
• Do Not Miss diagnoses
  • Mycotic aneurysm: Although less common, mycotic aneurysms are a serious complication of bacterial endocarditis and can cause a range of symptoms, including dizziness, due to their potential to rupture or cause embolic events. Missing this diagnosis could be catastrophic.
  • Meningitis: While the patient does not have typical symptoms of meningitis (such as fever, headache, or stiff neck), bacterial endocarditis can lead to meningitis, especially if the causative organism is virulent. This diagnosis should not be missed due to its severity.
• Rare diagnoses
  • Brain abscess: This is a rare but serious complication of bacterial endocarditis. Brain abscesses can cause a wide range of neurological symptoms, including dizziness, but are less likely given the absence of other focal neurological signs or symptoms suggestive of an abscess, such as headache or seizures.