Parasitoses with central nervous system involvement.

Most of the parasitoses manifest systemically, including the central nervous system (CNS). Among the most prevalent parasitoses in Central Europe (cysticercosis, toxocarosis, echinococcosis, and toxoplasmosis), cerebral involvement is well recognized and part of the clinical presentation, which cannot be neglected. CNS involvement results from invasion of larvae of these parasites via the blood stream or by direct migration into the CNS. Most frequently larvae reside within the cerebral parenchyma, but sometimes also within the ventricles, in the meningeas within cerebral aneurysms, or in the parenchyma of the spinal cord. Depending on the stage of their development, they cause a local defect or more widespread damage, such as encephalitis, ventriculitis, ependymitis, arachnoiditis, meningitis, myelitis, polyradiculitis, mechanical obstruction of the arterial or cerebrospinal fluid (CSF) flow, or vasculitis with appropriate clinical presentations. These include epilepsy, headache, impaired consciousness, orientation, cognition, focal neurological motor, sensory, or vegetative deficits, or visual impairment. CNS involvement is diagnosed on the clinical presentation, the epidemiological background, blood and CSF investigations, imaging studies, and sometimes biopsy. Treatment is based on various antihelminthic agents and, occasionally, surgery.