Neurocysticercosis

Neurocysticercosis is a specific form of the infectious parasitic disease cysticercosis which is caused by infection with Taenia solium, a tapeworm found in pigs. Neuro-cysticercosis occurs when cysts formed by the infection grow within the brain causing neurologic syndromes such as epileptic seizures.

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.

Essential update: The American Academy of Neurology issues a treatment guideline on parenchymal neurocysticercosis

Guidelines issued in April 2013 by the American Academy of Neurology recommend use of albendazole plus a corticosteroid for the treatment of parenchymal neurocysticercosis. The guideline, which is also endorsed by the American Epilepsy Society, recommends treatment with albendazole (400 mg twice daily for adults or weight-based dosing for either adults or children) plus either dexamethasone or prednisolone to decrease the number of active lesions on brain imaging studies and reduce long-term seizure frequency.

Signs and symptoms

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

  • Epilepsy: Most common presentation (70%)
  • Headache, dizziness
  • 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

Diagnosis

Neurocysticercosis1
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 depending on the stage of evolution of the infestation:
Neurocysticercosis2

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

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 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/┬ÁL); however, this also occurs in neurosyphilis and CNS tuberculosis
  • 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

Management

Treatment of neurocysticercosis depends upon the viability of the cyst and its complications. 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 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

    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
  • 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