Approach
Treatment varies depending on the location and number of parasites and the host's response. Antiparasitic therapy is the mainstay of therapy in most patients; however, additional interventions including corticosteroids, anticonvulsants, and surgical intervention may be required in extra-intestinal disease. Patients with neurocysticercosis may present with elevated intracranial pressure, which is a medical emergency.[44]
Intestinal infection
When stool examination reveals evidence of tapeworm infection (e.g., Hymenolepis nana, Diphyllobothrium latum, Taenia saginata, and T solium), the treatment of choice is the broad-spectrum antiparasitic drug praziquantel. Praziquantel has excellent activity against all tapeworms. It is given as a single dose in both children and adults.[45] Infections with H nana require higher doses. Other antiparasitic drugs, such as niclosamide, exist.
Central nervous system (CNS) manifestations
CNS manifestations include disease with T solium (neurocysticercosis) or Echinococcus species. In patients with neurocysticercosis, specific treatment depends on the location of the cysts.
Increased intracranial pressure can be life threatening and should be managed immediately. Antiparasitic therapy is not recommended until intracranial pressure is stabilised. Use of antiparasitic therapy in patients with elevated intracranial pressure can lead to fatal adverse events (e.g., herniation).[33] Once the patient is stabilised, management depends on the type of neurocysticercosis.
Active parenchymal disease:
Patients with untreated hydrocephalus or diffuse cerebral oedema (cysticercal encephalitis) require urgent management of elevated intracranial pressure with corticosteroids for diffuse cerebral oedema, or a surgical approach for hydrocephalus.[33]
Antiparasitic therapy (i.e., albendazole or praziquantel) is then started. The addition of corticosteroids is recommended to suppress the inflammatory effect of antiparasitic therapy, and may reduce the risk of generalised seizures in patients with active parenchymal cysts.[33][39][40][46]
Inactive parenchymal disease:
Inactive parenchymal disease (with calcified lesions) does not usually require treatment with antiparasitic therapy as there are no viable cysts.
Calcified lesions can be associated with symptomatic perilesional oedema. Guidelines recommend against the routine use of corticosteroids in these patients, as there are a few case reports that suggest rebound perilesional oedema can occur when corticosteroids are tapered or stopped.[33]
Surgical removal of seizure foci can be considered in select patients.[33]
Intraventricular disease:
Patients with active ventricular disease may present with obstructive hydrocephalus. Management of these patients is focused on relieving the intracranial hypertension with ventriculoperitoneal shunting.
Once intracranial pressure is stabilised, neuroendoscopic removal of cysticerci in the lateral and third ventricles is performed, while surgical removal of cysticerci in the fourth ventricle is recommended.[33] Patients with magnetic resonance imaging (MRI) findings of significant ependymal enhancement (secondary to adherence of lesions to the ependyma) may not be suitable for this surgery.[31]
Some experts do not recommend antiparasitic therapy before surgical removal as it may disrupt the integrity of the parasite and cause an inflammatory response that could prevent cyst removal.[46]
Corticosteroids are recommended in the perioperative period, or in combination with antiparasitic therapy after shunt placement.[33]
Subarachnoid disease:
Evidence regarding treatment of subarachnoid disease is limited as the condition is relatively rare and prognosis is very poor. There have been no controlled trials of subarachnoid disease management; however, case series in which patients were treated with antiparasitic drugs, corticosteroids, and shunting for hydrocephalus demonstrated improved prognosis.[47]
It is recommended that raised intracranial pressure is initially treated with shunting, and prolonged antiparasitic therapy (i.e., several months to more than 1 year), with slow tapering of corticosteroids.[47] Methotrexate may also be used as a corticosteroid-sparing agent in order to reduce the adverse effects associated with long-term corticosteroid use.[47][48] Some patients may also benefit from surgical debulking.[33]
Spinal/ocular disease:
Case-specific, individualised surgery is the mainstay of treatment for spinal cord disease. Antiparasitic therapy plus corticosteroids (especially in cases with spinal cord dysfunction) are also recommended. Intra-ocular cysticerci should be treated by surgical removal.[33]
General principles of treatment:
Antiparasitic therapy: monotherapy with albendazole is generally recommended. However, patients with greater disease burden (i.e., >2 viable cysts) may benefit from combination antiparasitic therapy (i.e., albendazole plus praziquantel). This recommendation is derived from studies done in patients with parenchymal disease.[33]
A randomised, double-blind, placebo-controlled phase II trial found much greater cysticidal activity (cyst resolution 95% versus 30%; complete cyst clearance 75% versus 25%) of albendazole plus praziquantel compared with albendazole alone.[49]
These findings were confirmed in a phase III study (double-blind, placebo-controlled) that also found that patients with viable intraparenchymal neurocysticercosis have increased parasiticidal effect with combination therapy of albendazole plus praziquantel compared with albendazole alone. The benefit was largely driven by the sub-group of patients with three or more viable cysts. No increased side effects were seen in the combination antiparasitic therapy arm.[50]
A Cochrane review found that albendazole monotherapy reduced the risk of seizure recurrence in patients with a single cyst who presented with seizures compared with placebo or no antiparasitic therapy (moderate-certainty evidence). Evidence for albendazole in patients with more than one cyst is lacking but suggests potential harm (very low-certainty evidence).[51]
Anticonvulsants: seizures may be controlled with the use of an anticonvulsant, regardless of the type of neurocysticercosis. Anticonvulsants can be tapered and stopped after resolution of cysts on MRI and if the patient is seizure-free for a certain period of time (dependent on the location of cysts), provided they have no risk factors for seizure recurrence. Evidence for the optimal duration of anticonvulsant treatment in patients with neurocysticercosis is limited.[52] The World Health Organization recommends considering discontinuation 6 months after the last seizure in patients with a single enhancing lesion and a low risk of seizure recurrence; treatment should be continued for at least 2 years in patients with calcified neurocysticercosis and epilepsy.[39] Choice of anticonvulsant is guided by availability, drug interactions, adverse effects, and cost. Many anticonvulsants should not be used in pregnant women due to their teratogenic effects.[33]
Corticosteroids: the optimal dose, duration, and formulation of adjunctive corticosteroid to administer with antiparasitic therapy have not been established. An open-label randomised trial compared conventional dexamethasone dosing with enhanced dexamethasone dosing in patients with viable parenchymal neurocysticercosis with recent (within 6 months) seizure activity. Although the study did not meet its primary end point of reducing seizure days or individuals with seizures, the study had two important findings. First, this study found that seizure activity was heightened during days 1 to 21 and decreased after day 21; second, that enhanced dexamethasone dosing reduced seizure activity from days 1 to 21. Adverse effects were not different between the two groups. These data suggest that patients with intraparenchymal viable neurocysticercosis at risk for seizure during the first 21 days of treatment may benefit from an enhanced corticosteroid regimen.[53] Corticosteroids are generally started prior to antiparasitic treatment.
Hepatic or thoracic manifestations
Hepatic or thoracic manifestations include echinococcosis (disease with Echinococcus species) and cysticercosis (infection with T solium). Surgical removal is the mainstay of treatment of hepatic echinococcal disease. Wide surgical resection for operable cases (e.g., hepatic lobectomy or liver transplantation) ensures total removal of cysts. Antiparasitic therapy is administered concurrently at least 2 weeks prior to the surgery and at least 1 month postoperatively. In pulmonary hydatid disease, prolonging combination therapy of albendazole and praziquantel from 2 weeks to 4 or 8 weeks prior to surgery may lead to an increased scolicidal response. Prolonging pre-treatment antiparasitic therapy may be considered if the patient is at high risk for intraoperative rupture.[54]
Medical therapy alone may result in cure for a small subset of patients, but disease often recurs without surgical intervention. Some success with the PAIR (puncture, aspiration, injection, and re-aspiration) procedure has been reported in appropriate patients. PAIR is performed with concurrent albendazole therapy to reduce the risk of cyst dissemination. The hydatid cyst is aspirated under computed tomography guidance, and a scolicidal agent is instilled into the cyst cavity. Fluid is then re-aspirated.[55][56]
Special patient groups
Pregnant women are treated in the same way as non-pregnant people, with the following considerations: antiparasitic therapy should be delayed until after delivery; corticosteroids may be used safely when necessary; and teratogenic effects should be taken into account when deciding on a suitable anticonvulsant. Children are generally treated the same as adults.[33]
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