Cognitive dysfunction, urinary retention, and a lesion in the thalamus--beware of possible toxocariasis of the central nervous system.

Toxocariasis of the central nervous system is usually characterized by an eosinophilic meningitis, encephalitis or myelitis. We here report a patient with an at least 7 years history of unexplained neurologic signs and symptoms. MRI showed a cystic lesion in the left thalamus, compatible with a parasitic infection. Blood and CSF analyses were positive for Toxocara canis IgG Western-blot, but were otherwise unremarkable. The case report raises the question whether there are chronic or late variants of this disease.