Types of neuro involvement
- Giant cysts: definition: cyst with diameter > 50mm.
- Spinal cord and peripheral nerve involvement is rare
- Two types of cysts tend to develop in the brain
- Regular, round or oval thin-walled cyst,
- Ranging in size from ≈ 3 to 20 mm
- Cyst located in the parenchyma or narrow subarachnoid spaces.
- This cyst contains a scolex (head), is usually static
- Produces only mild inflammation during the active phase
- Larger (4–12 cm),
- Cyst grows actively producing grape-like clusters
- Cyst located in the basal subarachnoid spaces
- May lack a scolex
- Cyst produces intense inflammation.
- There are no larvae in these cysts.
- These cysts usually degenerate in 2–5 years, during which the capsule thickens and the clear cyst contents are replaced by a whitish gel which undergoes calcium deposition with concomitant shrinkage of the cyst
Cysticercus cellulosae
Cysticercus racemosus
Images
Clinical presentation
- Seizures
- Most common symptom
- Most common cause of seizures in young adults in endemic areas
- Raised ICP
- Due to
- Hydrocephalus
- Giant cysts
- Present as
- Headaches
- Altered mental status
- Immunologic reaction to the infestation
- Cysticercotic encephalitis
- Neurological deficits
- Cranial nerve deficits
- Basal arachnoiditis
- Bruns syndrome
- A sudden onset of severe headaches and vomiting associated to a vestibular syndrome provoked by abrupt change in head position.
- It is related to an episodic obstructive hydrocephalous caused by an intraventricular mass that acts like a ball-valve mechanism.
- Caused by cysticerci cysts of the third and fourth ventricle
- Subcutaneous nodules
- Symptoms associated with neurocysticercosis in 271 patients with neurocysticercosis evaluated at Ben Taub general hospital, Houston, Texas
- ᵃSymptoms of hydrocephalus includes nausea, vomiting and headache.
Symptom | Number of patients (%) |
Seizures | 186 (69) |
Headache | 125 (46) |
Visual problems | 34 (13) |
Altered mental status | 36 (11) |
Symptoms of hydrocephalusᵃ | 31 (11) |
Location
- Tends to fall into 1 of 4 groups
- Found in 27–56% of cases with neural involvement.
- Larger, attaining a diameter of up to 60 mm.
- Round or lobulated.
- Cysts are adherent or free-floating and are located either in
- Dorsolateral subarachnoid space
- C. cellulosae type,
- Causing minimal symptoms
- Basal subarachnoid space
- Usually the expanding
- C. racemosus type
- Causes
- Arachnoiditis + fibrosis → chronic meningitis with hypoglycorrhachia (an abnormally low glucose concentration within the cerebrospinal fluid).
- Obstruct foramina of Luschka and Magendie → hydrocephalus,
- Entrapment of basal cisterns → cranial neuropathies (including visual disturbance).
- Extremely high mortality with this form
- Found in 30–63% of cases with neural involvement.
- Focal or generalized seizures occurs in ≈ 50% of cases (up to 92% in some series)
- Typically round and 5 to 20 mm in diameter
- Found in 12–18% of cases with neural involvement.
- Possibly gaining access via the choroid plexus.
- Pedunculated or free floating cysts occur → blocking CSF flow and cause hydrocephalus with intermittent intracranial hypertension (Brun syndrome).
- There may be adjacent ependymal enhancement (ependymitis)
- Found in ≈ 23% of cases with neural involvement.
Subarachnoid
Parenchymal
Ventricular
Mixed lesions
Evaluation
Diagnosis
- Imaging studies and confirmatory serologic tests
Laboratory evaluation
- Peripheral eosinophilia
- Mild elevation
- Inconsistent and thus unreliable.
- CSF
- May be normal.
- Eosinophils are seen in 12–60% of cases and suggests parasitic infection.
- Protein may be elevated.
- Stool
- <33% of cases have T. solium ova in the stool.
Serology
- From serum or CSF
- Enzyme-linked immunoelectrotransfer blot (EITB)
- Against anticysticercal antibodies
- 100% specific and 98% sensitive,
- Sensitivity is less (70%) in cases with a solitary cyst.
- EIBT has effectively superseded ELISA where titer is considered significant at 1:64 in serum, and 1:8 in the CSF;
- Checking for titer exceeding these thresholds in the serum produces a test that is more sensitive and in the CSF is more specific for cysticercosis.
- False negative rates are higher in cases without meningitis.
Radiographic
General
- A cystic lesion with an associated scolex (demonstrated as a 1- to 3-mm mural nodule) is diagnostic
- Neuroimaging studies that do not reveal a scolex, although suggestive of NCC, is not diagnostic
Soft-tissue X-rays may show calcifications in subcutaneous nodules,
- Thigh muscles
- Shoulder muscles.
Skull X-rays
- Show calcifications in 13–15% of cases with neurocysticercosis.
- May be single or multiple.
- Usually circular or oval in shape.
CT modified
- Good at detecting intracerebral calcifications
- Ring-enhancing cysts of various sizes representing living cysticerci.
- Little inflammatory response (edema) occurs as long as larva is alive.
- Characteristic finding
- Small (< 2.5 cm) low density cysts
- With eccentric punctate high density that may represent the scolex
- Low density with ring enhancement seen as an intermediate stage between living cyst and calcified remnant representing intermediate stage in granuloma formation.
- Resultant inflammatory reaction can cause edema, and basal arachnoiditis in cysts located in basal subarachnoid space.
- Often ring-enhancing
- Intraparenchymal punctate calcifications (granuloma)
- But usually without surrounding enhancement;
- Seen with dead parasites
- Hydrocephalus.
- Sometimes with intraventricular cysts, which may be isointense with CSF on plain CT50 and may require contrast CT ventriculography51 or MRI to be demonstrated
MRI
- MRI is much better at detecting cysticerci in the CSF
- MRI may also reveal the scolex, which is usually not visible on CT scans
- Early findings
- Nonenhancing cystic structure(s) with eccentric T1WI hyperintensity (scolex) with no inflammatory response. Lesions may be seen in parenchyma, ventricle, and subarachnoid space.
- The cyst collapses in later stages of parasitic evolution, with initial edema that gradually resolves with time.
- 4 Escobar's pathological stages
- Vesicular
- Viable parasite with intact membrane → no host reaction.
- Imaging
- Cyst with dot sign
- Colloidal vesicular
- Parasite dies within 4-5 years untreated, or earlier with treatment and the cyst fluid becomes turbid.
- As the membrane becomes leaky oedema surrounds the cyst.
- Most symptomatic stage.
- Granular nodular
- Oedema decreases as the cyst retract further;
- Enhancement persists.
- Nodular calcified
- End-stage quiescent calcified cyst remnant;
- No oedema.
TlWI | Vesicular stage | Colloidal vesicular stage | Granular nodular stage | Nodular calcified stage |
T1 Useful to detect intraventricularcysts | Cystic lesion isointense to CSF. May see discrete, eccentric scolex (hyperintense) | Cyst is mildly hyperintense to CSF | Thickened, retracted cyst wall; edema decreases | Shrunken, Ca++ lesion |
T2WI | Cystic lesion isointense to CSF. May see discrete, eccentric scolex. No surrounding edema. | Cyst is hyperintense to CSF. Surrounding edema, mild to marked. | Thickened, retracted cyst wall; edema decreases | Shrunken, Ca++ lesion |
FLAIR | Cystic lesion isointense to CSF. May see discrete, eccentric scolex (hyperintense to CSF); no edema. | Cyst is hyperintense to CSF. Surrounding edema, mild to marked. Useful to detect intraventricular cysts (hyperintense). | ||
T2*GRI Useful to demonstrate calcified scolex | ||||
DWI: Cystic lesion typically isointense to CSF | ||||
TI+C | No enhancement typical, may see mild enhancement. May see discrete, eccentric scolex enhancement. | Thick cyst wall enhances. Enhancing marginal nodule (scolex) | Thickened, retracted cyst wall; may have nodular or ring-enhancement | Small calcified lesion, rare minimal enhancement |
Treatment
Anthelmintic medication: antiparasitic and/or cysticidal regimens
- General
- Since many lesions resolve on their own, and there are significant side effects to these drugs, their use is controversial.
- The anthelmintic slightly increases the likelihood of radiological resolution of the cyst
- Reduces the likelihood of seizures
- In patients with symptoms of intracranial hypertension
- Anthelmintic treatment is started after symptoms subside (usually after 3 doses).
- ❌ Any cysticercocidal drug may cause irreversible damage when used to treat ocular or spinal cysts, even with corticosteroid use.
- Praziquantel
- Is an anthelmintic with activity against all known species of schistosomas.
- Several regimens have been published
- 50 mg/kg/d divided in 3 doses (same dose for pediatrics) for 15 days (doses of100mg/kg/d have been recommended because steroids reduce serum concentration by 50%).
- Produces a significant reduction in symptoms and in number of cysts seen on CT
- 10–100mg/kg/d×3–21 days
- High dose single day regimen: 25–30mg/kg q 2 hrs × 3 doses
- For intestinal infestation: single oral dose of 5–10mg/kg
- Side effects
- Due to dying of the paracite causing increased inflammation
- Worsening neurologic function (e.g., headaches, dizziness, seizures, and increased ICP)
- Albendazole
- 15mg/kg per day divided in 2–3 doses, taken with a fatty meal to enhance absorption (same dose for paediatrics),
- May be given for 3 months,
- Can be stopped sooner if imaging shows resolution.
- More parasiticidal than praziquantel and may have fewer side effects.
- Niclosamide (Niclocide® and others) may be given orally to treat adult tapeworms in the GI tract.
- ℞ 1 gm (2 tablets) chewed PO, repeated in 1 hour (total = 2 g).
- Intraventricular disease
- There is no consensus on the efficacy of medical treatment for intraventricular cysts.
Antiepileptics
- Seizures usually respond to a single AED.
- However, the risk of seizures may be lifelong.
- Risk factors for recurrent seizures
- Calcified brain lesions,
- Multiple seizures,
- Multiple brain cysts.
Steroids
- Corticosteroids should be used in all patients.
- Aim
- May temporarily relieve symptoms
- May help decrease edema that tends to occur initially during treatment with anthelmintic drugs.
- If possible, start 2–3 d before anthelmintics (e.g. dexamethasone 8mg q 8 hours), on day 3 decrease to 4mg q 8 hours, and on day 6 change to prednisone 0.4 mg/kg per day divided TID.
- Taper steroids after anthelmintics are discontinued.
Surgery
- Aim
- CSF diversion
- Necessary for patients with symptomatic hydrocephalus,
- Tubing may become obstructed by granulomatous inflammatory debris.
- To establish the diagnosis.
- Stereotactic biopsy may be well suited for some cases, especially with deep lesions.
- For lesion that do not respond well with anthelmintics
- Spinal cysts42 and for intraventricular cysts,
- Giant cysts causing HCP
- Anthelmintics may be required even after complete surgical removal because of possibility of relapse.
Made with Bullet