Neurocysticercosis is the result of accidental ingestion of eggs of Taenia solium (ie, pork tapeworm), usually due to contamination of food by people with taeniasis. In developing countries, neurocysticercosis is the most common parasitic disease of the nervous system and is the main cause of acquired epilepsy. In the United States, neurocysticercosis is mainly a disease of immigrants.

Signs and symptoms

Clinical manifestations of neurocysticercosis vary with the locations of the lesions, the number of parasites, and the host's immune response. [3] Many patients are asymptomatic. Possible symptomatic presentations include the following:

Epilepsy: Most common presentation (70%)

Headache, dizziness

Stroke

Neuropsychiatric dysfunction

Onset of most symptoms is usually subacute to chronic, but seizures present acutely

Abnormal physical findings, which occur in 20% or less of patients with neurocysticercosis, depend on where the cyst is located in the nervous system and include the following:

Cognitive decline

Dysarthria

Extraocular movement palsy or paresis

Hemiparesis or hemiplegia, which may be related to stroke, or Todd paralysis

Hemisensory loss

Movement disorders

Hyper/hyporeflexia

Gait disturbances

Meningeal signs

See Clinical Presentation for more detail.

Diagnosis

Neurocysticercosis is commonly diagnosed with the routine use of diagnostic methods such as computed tomography (CT) and magnetic resonance imaging (MRI) of the brain.

Imaging studies

CT findings vary as follows, depending on the stage of evolution of the infestation:

Vesicular stage (viable larva): Hypodense, nonenhancing lesions

Colloidal stage (larval degeneration): Hypodense/isodense lesions with peripheral enhancement and perilesional edema

Nodular-granular stage: Nodular-enhancing lesions

Cysticercotic encephalitis: Diffuse edema, collapsed ventricles, and multiple enhancing parenchymal lesions

Active parenchymal stage: The scolex within a cyst may appear as a hyperdense dot

Calcified stage: When the parasite dies, nodular parenchymal calcifications are seen (see the image below) Computed tomographic (CT) scan of the brain in a patient who presented with an episode of generalized tonic-clonic seizure. Note the calcified lesion in the left parieto-occipital region. Subsequent evaluation confirmed the diagnosis of neurocysticercosis. View Media Gallery

MRI is the imaging modality of choice for neurocysticercosis, especially for evaluation of intraventricular and cisternal/subarachnoidal cysts. Findings on MRI include the following:

Vesicular stage: Cysts follow the CSF signal; T2 hyperintense scolex may be seen, with no edema and usually no enhancement

Colloidal stage: Cysts are hyperintense to the CSF; there is surrounding edema, and the cyst wall enhances

Nodular-granular stage: The cyst wall thickens and retracts, there is a decrease in edema, and nodular or ring enhancement is present

Lab studies

CSF analysis for neurocysticercosis is indicated in every patient presenting with new-onset seizures or neurologic deficit in whom neuroimaging shows a solitary lesion but does not offer a definitive diagnosis. CSF is contraindicated in cases of large cysts causing severe edema and displacement of brain structures, as well as in lesions causing obstructive hydrocephalus.

CSF findings include the following:

Mononuclear pleocytosis

Normal or low glucose levels

Elevated protein levels

High IgG index

Oligoclonal bands, in some cases

Eosinophilia (5-500 cells/µL); however, this also occurs in neurosyphilis and CNS tuberculosis [4]

CSF ELISA for neurocysticercosis has a sensitivity of 50% and a specificity of 65%

Other tests are as follows:

Stool examination: 10-15% of neurocysticercosis patients have taeniasis

Brain biopsy: Necessary only in extreme cases

See Workup for more detail.

Management

Treatment of neurocysticercosis depends upon the viability of the cyst and its complications. [5] If the parasite is dead, the approach is as follows:

Treatment is directed primarily against the symptoms

Anticonvulsants are used for management of seizures; monotherapy is usually sufficient

Duration of the treatment remains undefined

If the parasite is viable or active, treatment varies as follows:

Patients with vasculitis, arachnoiditis, or encephalitis: A course of steroids or immunosuppressants is recommended before the use of anticysticercal drugs

Antiparasitic treatment [6] with albendazole is also useful in cysticercosis of the racemose type (ie, multiple cysts in the basal cisterns)

Patients with parenchymal, subarachnoid, or spinal cysts and without complications (eg, chronic epilepsy, headaches, neurologic deficits related to strokes, and hydrocephalus): anticysticercal treatment can be considered, with the concomitant use of steroids

Multiple trials with anticysticercal treatment may be required for giant subarachnoid cysts

Patients with seizures due to viable parenchymal cysts: antiparasitic therapy [7]

Indications for surgical intervention and recommended procedures are as follows:

Hydrocephalus due to an intraventricular cyst: Placement of a ventricular shunt, followed by surgical extirpation of the cyst and subsequent medical treatment [8]

Multiple cysts in the subarachnoid space (ie, the racemose form): Urgent surgical extirpation

Obstruction due to arachnoiditis: Placement of a ventricular shunt followed by administration of steroids and subsequent medical therapy

See Treatment and Medication for more detail.