2. Introduction
Neurocysticercosis (NCC) is the infection of the CNS by the larval stage of the
pork tapeworm Taenia solium.
Infection may develop in any organ- CNS (parenchyma, subarachnoid spaces,
ventricles and spinal cord), eyes and muscles are the most commonly involved.
Most common manifestation is epilepsy but can have several other neurological
manifestations.
3. Epidemiology
NCC is endemic in most Latin American countries, sub-Saharan Africa, and large
regions of Asia (including Indian subcontinent and China).
Rare in developed countries, can occur in travelers/immigrants.
A study from North India found point prevalence of NCC - 4.5/1000. In pig farming
community it is upto 15 %.
Proportion of NCC among patient with epilepsy is estimated @ 29 %. In those with
partial seizures it was >50 %.
4. Life cycle of Taenia solium
Taenia solium requires two hosts to complete its life cycle.
Pigs (intermediate host) contain the cystecerci, primarily in muscle.
Humans (definitive host) infected by consuming undercooked pork containing live
T.solium cysticerci.
Cysticerci develop into adult tapeworm which releases eggs in human feces.
Eggs contaminate soil/vegetation, when ingested by pigs/humans eggs develop into
larvae which pass through intestinal mucosa and reach various tissues.
7. Modes of infection
Sources of infection- persons withTaeniasis (acquired from pork).
Transmission ways-
not spread from person to person directly
persons withTaeniasis will shed tapeworm eggs in their bowel movements
8. Modes of infection
Infection can happen by accidentally swallowing pork tapeworm eggs
Through-
drinking contaminated water or food
by putting contaminated fingers to mouth (external autoinfection)
by internal autoinfection
9. Disease spectrum of T.solium
Taeniasis = adult tapeworm in small intestine
• Usually asymptomatic (eggs or proglottids in feces)
• Vague abdominal symptoms
Cysticercosis = T. solium larvae in human tissues (eg, muscle)
• Usually asymptomatic
• Painless subcutaneous nodules in arms and chest
Neurocysticercosis (NCC) = cysts in the central nervous system
• Most severe manifestation
10. Etiopathogenesis
Clinical expression, management and prognosis of NCC varies depending on
the number of CNS lesions, their stage, size, location and host inflammatory
response.
Studies have identified a number of mechanisms used by the cycticercus to
modulate host’s immune response.
• Protease inhibitor-Taeniaestatin
• Sulfated polysaccharides
• Parasite paramyosin
• Prostaglandins
• Stimulate antibody production
11. Etiopathogenesis
Although, cysticerci reach mature size within a few weeks, there a period
of several years between exposure and onset of symptoms.
When parasite degenerates there is a brisk inflammatory response.
The seizures are thought to result not from the parasitic infection per se,
but from the host response.
12. Types of Neurocysticercosis
1. Intraparenchymal NCC
Most common form, seen at grey white matter junction.
Single or Multiple.
Range in size from a few mm to 1 to 2 cm.
Commonly seen in children >5 years but can occur in toddlers and infants.
13. Types of Neurocysticercosis
Intraparenchymal NCC cont…
Seizures are most common manifestation of intraparenchymal NCC.
1/3rd may have associated headache and vomiting.
Papilloedema occurs in 2 to 7 %.
Neurological deficits seen in 4 to 6 %.
Seizures respond well to monotherapy.
Cysticercal Encephalitis- results from large number of cysticeci in brain parenchyma
with diffuse inflammation and edema.
14. Types of Neurocysticercosis
The parenchymal cysts evolve through 4 stages-
The vesicular cyst
Colloidal stage
Granular nodular stage
Nodular calcified stage
16. Types of Neurocysticercosis
2. Extraparenchymal NCC
Ventricular NCC- can obstruct CSF flow causing hydrocephalus. CT may
reveal only hydrocephalus and no cysticerci.
Subarachnoid NCC- can occur in the gyri, fissures, basilar cisterns.
18. Types of Neurocysticercosis
Other forms of Cysticercosis
Spinal Cysticercosis (intramedullary/extramedullary)
Ocular Cysticercosis
In Muscles
In Subcutaneous tissue
Other organs
A single patient may have multiple types and locations of cysticercus.
20. Clinical Manifestations
Asymptomatic.
Most common manifestation is Seizure (focal, secondary generalized or
generalized). (80%)
Headache is common (unilateral/bilateral)- may reflect raised ICT or vasculitis.
Focal neurological deficits (16%)
Symptoms/signs of raised ICT-nausea, vomiting, altered mental status, visual
changes, dizziness, cerebral edema. (12%)
Neurocognitive defects- leaning disability, psychosis, depression. (5%)
21. Imaging
CT
Parenchymal cysts- usually appear as single, small (<20mm) with ring/disk
enhancement and eccentric hyper dense scolex. Multiple lesions give ‘starry
sky’ appearance. (colloidal stage).
Enhancement indicates inflammation. Live vesicular cysts are non-enhancing.
Extra-parenchymal cysts- may show hydrocephalus, enhancement of
tenctorium and basal cisterns and occasionally infarcts.
22. Imaging
MRI
Superior to CT in detecting cysts in ventricles, posterior fossa, brainstem,
small cysts.
Small calcified lesions may be missed.
Magnetization transfer images (MT) and magnetization transfer ratio (MTR),
recovery (FLAIR) and fast imaging employing steady-state acquisition
(FIESTA) sequences for lesions not visible on routine MRI.
23. SerologicalTests
Seropositivity depends on parasite load and endemicity. False positive and false
negative results can occur.
False-negative result:
Single lesions
Calcification
False-positive:
Other parasitic infections
High percentage of false positive for patients from endemic area
24. SerologicalTests
EITB assay- uses lentil lectin purified glycoprotein antigens (LLGP) to detect
antibodies to T soliumin in serum. Sensitivity 98% (multiple parasites), 50-70 %
(solitary cysticercus).
Detection of anticysticercal antibodies in the CSF by ELISA.
Detection of circulating parasitic antigens in serum by ELISA with monoclonal
antibodies is experimental.
In patients with reliable diagnosis of NCC by imaging studies, immunological test is not
required, since a negative test will not discard a NCC.
25. Other lab tests…
Eosinophilia may occur.
CSF-
Usually done to rule out other causes.
Can be normal in inactive disease.
Moderate pleocytosis (mostly mononuclear cells; upto 300/mm3), increased
protein (50-300 mg/dl). Correlate with disease activity and whether or not the
parasites are located in sub-arachnoid space.
26. Other lab tests…
Biopsy of subcutaneous nodules.
Radiographs of skeletal muscles.
Specific coproantigen detection by ELISA for screening forT solium carriers.
Stool examination forT.solium eggs has poor sensitivity.
27. Diagnosticcriteria Definitive diagnosis- one
absolute criterion or two major
plus one minor and one
epidemiologic criteria
Probable diagnosis- one major
plus two minor criteria, one major
plus one minor and one
epidemiologic criteria, three
minor plus one epidemiologic
criteria.
28. Differential diagnosis
Tuberculoma
(presence of raised ICT, progressive
focal neurodeficit, size >20mm,
lobulated irregular shape, midline shift
& marked edema, lesions at base of
brain)
Special MRI sequences – diffusion
weighted MRI and proton magnetic
resonance spectroscopy (MRS) are
being tried.
Case discussion- A two month old child was referred for
evaluation of fever associated with fits. Plain CT brain showed
a 1.1.x 1.0 cms. round hypodense lesion in the right frontal
lobe. There was dilatation of all the ventricles, basal cisterns.
The anterior fontanalle was bulging. On contrast study there
was dense enhancement of basal meninges, dense ring
enhancement ( 4 mm thick ) of the the right frontal lobe
lesion.
30. Management
Emergency care
Manage seizure activity
Supportive care (A-B-C)
Monitor, and correct metabolic abnormalities
Anticonvulsants are effective.
Evidence of increased ICP- Steroids, osmotic agents, and/or diuretics
Initiate proper diagnostic procedures
Blood work and imaging
31. Management
Intraparenchymal NCC- Symptomatic treatment, anti-parasite treatment or
surgery ?
Calcified cysts only- antiepileptic, analgesic, and anti-inflammatory drugs; for
seizures relapses, repeat imaging looking for peri-calcification oedema. AED for at least
2yrs since last seizure. No anti-parasite drugs.
*One or more cystic or degenerating lesions- antiepileptic, analgesic, and anti-
inflammatory drugs; antiparasitic treatment under hospital conditions with steroid
treatment. DiscontinueAED in single lesions after they resolve (without calcification).
*Level 1 evidence
Cysticercal encephalitis- Manage intracranial hypertension; do not use antiparasitic
drugs.
32. Management
Asymptomatic parenchymal lesions
• Prophylactic AED not justified in calcified lesions without seizures.
• Viable cysts- Give prophylactic AED when antiparasite treatment is also
planned.
Repeat neuroimaging after 3-6 m to document lesion resolution. Repeat
course of cysticidal therapy if persistent lesion.
33. Management
Drugs:
• Albendazole- 15mg/kg/day in 2-3 divided doses for 2-4 weeks. Shorter
courses of 3 to 14 days tried in single lesions.
• Praziquintal- 50mg/kg/day, less effective than albendazole.
• Combinations of two antiparasitic drugs- increased cyst clearance in
multiple lesions.
• Steroids-
Dexamethasone- 0.1 mg/kg/day i.v starting one day before antiparasite
drugs, give for 1 to 2 weeks then taper.
Prednisolone- 1 to 2 mg/kg/day.
36. Management
Other forms of NCC
Spinal- Intramedullary cysts are treated with surgery, albendazole with
steroids is being tried. Subarachnoid cysts can migrate so imaging is done
just before surgery.
Ocular- Surgical management is the standard of care.
37. Prognosis
Single lesions- good prognosis, disappears in >60% at 6m.
Seizure recurrence is 10-20% with single lesions, multiple lesions have
more frequent seizures.
Prognosis is poorer in cysticercal encephalitis and extraparenchymal
NCC.
38. Prevention
T solium infection is one of a few diseases targeted for focal
elimination and eventual eradication by the International Task Force
for Disease Eradication.
Public education, proper hygiene, provision for toilets.
Safe handling of meat, strict animal husbandry and meet inspections
procedures.
39. Prevention
Mass deworming of population with Niclosamide or Praziquintal.
Mass vaccination of pigs and treatment of pigs with Oxfendazole.
Community interventions reduce rate of epilepsy in hyper-endemic areas.
40. Conclusion
NCC is a common cause of seizures and other neurological manifestations
and needs to be considered in D/D of many neurological conditions.
Treatment with cycticidal therapy leads to reduction in seizure frequency
and faster resolution of lesions.
Children with a single or few lesions have a good outcome.
Prevention of NCC is important and feasible.
Prevalence in low in Islamic countries due to lack of pork consumption.
In endemic areas the prevalence of antibodies to T.solium antigens is upto 10% and 10-20% of the general population showing residual intraparenchymal brain calcification.
1.Ingestion of cyst-infected pork causes taeniasis and ingestion of T.solium eggs excreted by a tapeworm carrier leads to Cysticercosis.
2.So NCC can occur even in those who don’t consume pork.
3.Open field defecation and food handlers are a major source of infection.
Vesicular cyst- has a thin semitransparent wall, is filled with clear fluid, and has eccentric opaque 4-5mm scolex. There is no inflammation around it and it is usually asymptomatic. Imaging hallmark is clear fluid filled cyst with eccentric scolex without contrast enhancement.
Colloidal stage- After an inflammatory response is elicited, the larva undergoes hyaline degeneration and the cyst fluid becomes opaque and gelatinous. The membrane becomes leaky. This is the most symptomatic stage.
Granular nodular stage- The cyst contracts and the walls are replace by focal lymphoid nodules and necrosis. Enhancement persists.
Nodular calcified stage-end-stage quiescent calcified cyst remnant; no oedema.
Ventricular and subarachnoid NCC are often accompanied by parenchymal NCC.
NCC over gyri behave similar to parenchymal NCC. NCC in fissures esp. Sylvian fissure can enlarge massively and cause midline shift.
NCC in basilar cisterns is difficult to visualize, causes communicating hydrocephalus and has poor prognosis.
Seizures- are associated with active parenchymal cysts thought to be provoked by inflammation. Some inactive calcified lesions also present with seizures and they are more likely to have seizure recurrence on withdrawal of anticonvulsants.
NCC can cause any neurological deficit of central origin. Mechanism- parenchymal brain cyst, edema, subarachnoid cyst, cranial nerve entrapment, vasculitis and infarcts.
EITB- Enzyme linked immunoelectro transfer blot
EITB- Enzyme linked immunoelectro transfer blot
Albendazole is less expensive, fewer side effects, better penetration into subarachnoid space, co-administration with phenytoin/carbamazepine does not decrease its bioavailability.
Simultaneous administration of albendazole with praziquintal increases serum albendazole concentrations by 50%.
Several factors make eradication possible- human beings
are the only defi nitive host; the intermediate host is a
domestic animal whose exposure to ova can be controlled;
sensitive diagnostic tests for taeniasis and cysticercosis
allow identification of infected people and pigs; good
treatment regimens are available for taeniasis and
porcine cysticercosis; and pig vaccines were highly
efficacious under controlled and field conditions.