“Masked helminth in the brain” Dr. Gercois Human Dr. Lisel Richter-Joubert

University of Cape Town – Groote Schuur Hospital

Classic imaging features (Escobar's stages):

Multiple cysts in varying stages of evolution with an identifiable scolex are the

classical diagnostic features.3

Vesicular: “Cyst with Dot sign”.3

Colloidal vesicular: Cyst fluid becomes turbid with surrounding oedema.3

Cyst wall thickens and brightly enhances.3.

Granular nodular: Oedema and enhancement decreases and the cyst retracts.3

Nodular calcified: End-stage quiescent calcified nodule with no oedema or

enhancement on CT.3 Long term enhancement may be evident on MRI and may

predict ongoing seizures.3 Cyst shrinkage and calcification can take months to years.4

Recent studies show that recurrent seizures are caused by an inflammatory

response to antigens trapped and exposed the calcium matrix.4,5

Any organ can be affected but cysticerci are classically deposited in muscle, liver and

lung.6 Prevalence of ocular/orbital cysticercosis ranges from 10-30% in endemic areas.10

Extra-ocular muscle myocysticercosis is reportedly the most common orbital form, while

posterior segment cysticercosis is the most common ocular form.11

Case examples seen at GSH:

Neurocysticercosis Subtypes: Parenchymal: Most common form.5 Solitary cysts are seen in 20-50% of cases.6 Parenchy-

mal form is difficult to distinguish from the subarachnoid form as cysts in the deep sulci may

appear intra-axial.6 Giant neurocysticercosis cyst is rare, defined as a cyst larger than 4 cm.7

Subarachnoid (3.5%5): Cysts within basal cisterns tend to agglomerate in

a racemose form.5 A scolex is typically not seen (degenerated) and there

is abnormal growth of the cystic membranes.8 Enhancement of the

surrounding leptomeninges indicates the presence of arachnoiditis.5

Other complications include hydrocephalus, vasculitis and infarction.5

Intraspinal (0.7%-5.85%7): Cysts can be in the intramedullary space

(rare with only 55 cases reported)9 or in the subarachnoid space, where

they are most commonly located in the lower thoracic spine due to

the artery of Adamkiewicz.5

Intraventricular (17 –22% 5,7):

Usually a solitary cyst, most commonly seen in the 4th ventricle (53%8),

followed by the 3rd ventricle (27%), the lateral ventricles (11%) and

cerebral aqueduct of Sylvius (9%).5 MRI is superior to CT in depicting the

wall, and scolex, which may not be present.5 The cyst may evolve like the

parenchymal cyst but calcification is rare.5

‘Masked’ intraventricular case: 40 year old male with a history of headaches, developed left hemiplegia with loss of consciousness.

Treatment:

Medical

Albendazole drug of choice, particularly for subarachnoid and ventricular cysts.4

Prolonged (1 month), higher dose or repeat treatment may be needed in large

subarachnoid or interventricular cysts.4

Surgical

Neuroendoscopic resection or aspiration for large or intraventricular cysts.

Medical management in these forms is less favoured because of poor

cysticidal CSF penetration, delay in response and, lysis of the cyst leading to

ependymitis.4

Placement of a ventriculoperitoneal shunt is indicated in cases of

intracranial hypertension before the use of antiparasitic drugs.4

Cysto-peritoneal shunt in complicated cases.4

Most centres combine surgery with medical treatment, which consists of

albendazole, steroids ad ant-epileptic treatment .12

References:

Extra-neural cysticercosis:

Don’t forget the “masked helminth”!

1. www.uptodate.com/contents/cysticercosis 2. www.pathologylearningcentre.uct.ac.za/neurocysticercosis 3. www.radiopaedia.org/articles/neurocysticercosis 4. Seddighi A, et al (2015) Neurocysticercosis: Manifestations, Diagnosis and Treat-ment. International Clinical Neuroscience Journal 2(4): 121-127 5. Zhao JL, et al (2015) Imaging spectrum of neurocysticercosis. Radiology of Infectious Diseases 1: 94-102 6. www.my.statdx.com/neurocysticercosis 7. Pant HP, Sharma S (2015) Giant Neurocysticercosis. J Clin Case Rep 5: 601 8. Mahale R, Mehta A, Rangasetty S (2015) Extraparenchymal (racemose) Neurocysti-cercosis and its Multitude Manifestations: A Compressive Review. J Clin Neurol 11(3):203-211 9. Shah S, Dalvie S (2017) Cysticercosis of the Spine: A Review. Arch Parasitol 1: 110 10. Patel D, et al (2011) Ocular cysticercosis: A Review. Bombay Hospital Journal, Vol. 53 11. Dhiman R, et al (2017) Cysticercosis of the eye. Int J Ophthalmol 10(8):1319-1324 12. Jensen TO, Post JJ (2016) Intraventricular neurocysticercosis: Presentation, diagno-sis and management. Asian Pacific Journal of Tropical Medicine 9(8): 815–818 Lifecycle: curtesy of radiopedia.org

Post-shunting CT:

Due to the renewed mass effect, the patient subsequently

underwent a cysto-peritoneal shunt.

Differential diagnosis (IV cyst):3,6

Infective:

• hydatid cyst

• giant neurocyst

• amoebic abscess

Tumour/ tumour-like:

• Arachnoid cyst

• Choroid plexus cyst

• Epidermoid cyst

• Ependymal/ neuroepithelial cyst

• Ganglioglioma

Patient was urgently taken to theatre by neurosurgery

team. On endoscopy, an intraventricular cyst was

visualised and clear fluid was aspirated.

On review of the CT, a large cyst could be seen

obstructing the temporal horn.

Few small punctate calcification in the cerebral

convexities were clues to the diagnosis.

Diagnosis: Our case was histologically proven, however

diagnosis can also be made on serum and CSF

(detecting antibodies, T. solium antigens or

DNA PCR).12

MRI 3 days later showed:

• Enlargement of the encysted

right temporal horn

• No intraventricular cyst

• No scolex

• Right occipital infarct as sequelae from the uncal herniation

At this stage neurocysticercosis was histologically confirmed.

Complications:5,6 Acute hydrocephalus

Meningitis

Vasculitis

Infarcts

Granular ependymitis

Post-endoscopy CT:

Neurocysticercosis is one of the most common parasitic central nervous system infections seen with approximately 1.9 –

6.16 million people in sub-Saharan Africa infected.¹ In South Africa the highest prevalence is in the Eastern Cape (20%),

where there were an estimated 34 500 neurocysticercosis-associated cases of epilepsy in 2004.²