Clinical Reasoning: A 12-Month-Old Male Child With Staring Episodes, Ataxia, and Right-sided Weakness

Area of Science:

• Neurology
• Infectious Diseases
• Parasitology

Background:

• Baylisascaris procyonis (raccoon roundworm) is a rare cause of eosinophilic meningoencephalitis.
• Neural larval migrans typically present with severe neurological deficits and have historically poor outcomes.

Observation:

• A case of an infant with Baylisascaris neural larval migrans is presented, exhibiting hemiparesis, ataxia, and cortical blindness.
• Eosinophilia was initially missed due to automated cell differential misidentification of eosinophils as monocytes.
• Diagnosis was confirmed by repeated serum and CSF testing revealing eosinophilia and positive antibody testing.

Findings:

• This case highlights the potential for near-complete neurologic recovery with early recognition and treatment.
• The study emphasizes the critical importance of accurate eosinophil identification in diagnosing eosinophilic meningoencephalitis.
• Automated cell differentials may erroneously identify eosinophils as monocytes, delaying diagnosis.

Implications:

• Early diagnosis and prompt treatment of Baylisascaris infections are crucial for improving patient outcomes.
• Clinicians should be aware of potential misidentification of eosinophils by automated systems.
• This case underscores the need for careful review of peripheral blood and CSF differentials in suspected cases of eosinophilic meningoencephalitis.