Traveling Cysticercosis from Orbital Extraocular Muscle to Subconjunctival location and the final Extrusion

1. Traveling Cysticercosis � from Orbital (Extraocular Muscle) to Subconjunctival location and the final Extrusion/ Surgical Removal Shishir Agrawal MS DNB FRCS MRCOphth FRF Jaya Agrawal MS DNB MNAMS FRCS Trilok P Agrawal MS �T P Agrawal Institute of Ophthalmology 61 Shivaji Road, Meerut, U.P., INDIA Tel: +91-121-2640646/ 2650642, Email: dr_shishir@vsnl.com

3. Man can also act as an intermediate host and harbor the cyst. Cysticercosis is the infestation of humans by Cysticercus cellulosae, the larval form of Taenia solium. The terminal gravid segments are passed into the feces and eaten by pig, the usual intermediate host. On reaching its alimentary canal, these hatch, penetrate the gut wall to gain entrance into the systemic circulation and the naked oncospheres are ultimately filtered out into the striated muscles and various tissues, where they undergo development, encyst and expand into fluid-filled bladders to form cysticerci. These are ellipsoid bodies with an opalescent transparency measuring 0.1 to 2 cm with a dense milky white spot at the side where the scolex remains invaginated.

4. In humans, ingestion of ova via improperly cooked pork, or food (vegetables)/ water contaminated with eggs, or by autoinfection either from contaminated hands or by reverse peristaltic movements leads to cysticercosis. It is to be noted that infection can occur even in those who don�t eat pork via food prepared by an infected individual from endemic region. Cysticerci can be found in subcutaneous tissue, skeletal muscles, central nervous system, viscerae and eyes. Although only a mild tissue reaction occurs with a few viable cysticerci, heavy infestation can cause more marked generalized symptoms. Symptoms in cysticercosis occur mainly from invasion of the central nervous system. Cysticerci can remain alive for 3 to 5 years. Subcutaneous nodules may be palpable.

5. OCULAR In and around the eye, the cyst can invade almost any ocular, orbital or adnexal tissue. It could present in retina (subretinal or intraretinal), vitreous, orbit (extraocular muscle or retro-orbital space), conjunctiva (subconjunctival), eyelid, optic nerve, anterior chamber, lens, iris, cornea or lacrimal gland.

6. Extraocular muscle and subconjunctival tissue are the two commonest sites of presentation of extraocular/ adnexal cysticercosis, involvement occurring probably through anterior ciliary arteries. These have been more common in reports from India.

7. Extraocular muscle cysticercosis, the commonest form of orbital cysticercosis, typically presents with signs of orbital inflammation � a red eye, restricted ocular motility and/ or proptosis.

8. A painful inflammatory proptosis with restricted ocular motility when present in an individual with a history of exposure to an endemic area is diagnostic of myocysticercosis. Though it occurs at any age, the majority of patients are usually children and young adults in their first two or three decades. The lesion excites a recurrent severe inflammatory reaction resulting in considerable pain accompanied by edema and chemosis. There is a decreased ocular motility in the direction of action of the involved muscle and a restriction of the opposite movement (diplopia).

10. We have seen it in a large number of orbital cysticerci cases (49 patients) that myocysticerci are precursors of subconjunctival cysticerci, which finally extrude out spontaneously (Agrawal S, unpublished work, 2003).

11. Severe uveitis in a case of orbital cysticercosis Involvement of levator palpebrae superioris results in ptosis. Superior oblique muscle cysticercosis may present as Brown syndrome.

12. Pseudo-retinal detachment At times, fundus appearance of a solid-looking retinal detachment caused by orbital cysticercosis mechanically indenting the eyeball can be seen, all the three coats of the eyeball pushed in from outside (very well supported by ultrasonography (USG) and computed tomography (CT) scan). The term pseudo-retinal detachment has been coined for it because it is not a true retinal detachment, there being no subretinal fluid. Retinal striae support the mechanical nature of the lesion.

13. Orbital/ adnexal cysticercosis is conclusively diagnosed by aids such as USG, CT scan or magnetic resonance imaging (MRI) besides clinical presentation, USG being most economical. Finding a cyst with an eccentric shadow of the scolex is pathognomonic.

14. The segments/ eggs can be found in the faecal sample; perianal swabbing is important in diagnosis of taeniasis. An adult patient presenting with epilepsy for the first time should be suspected of having neurocysticercosis, especially with history of exposure to a hyperendemic area. Contrast-enhanced CT scan and MRI are required for brain lesions. These patients may have subcutaneous nodules (in 50%). Radiologic examination of the limbs and skull may show calcified cysts. Skin/ subcutaneous nodule biopsy is diagnostic. Eosinophilia may be found in blood. Serological tests like indirect hemagglutination (IHA) (positive in 85% of patients and titers of 1:64 considered diagnostic) and complement fixation may be used; however, these cross-react with hydatid antigen, etc., and also give false positives to patients having the adult worms only. Cerebrospinal fluid complement fixation test is more specific. ELISA (enzyme-linked immunosorbent assay) for anticysticercus IgG is more sensitive but again cross-reacts with Taenia saginata/ echinococcus/ coenurus. Enzyme-linked immunoelectro transfer blot (EITB) assay is highly sensitive and specific (98%).

15. Differential Diagnosis Diagnosis of ocular cases may be difficult in the presence of media haze from inflammation; in children different causes of leukocoria have to be ruled out. Orbital cases may present as cellulitis, pseudotumor or subconjunctival abscess. Epilepsy, brain tumours, and other types of neurologic and psychiatric disorders may be simulated in neurocysticercosis. Prophylaxis Infection is prevented by eating thoroughly cooked pork (56?C for 5 minutes), properly washed and boiled vegetables, drinking clean water, and by maintaining personal hygiene.

16. Treatment � Medical & Surgical Praziquantel (50 mg/ kg/ day) had been the drug of choice for taeniasis and cysticercosis. Albendazole (15 mg/ kg/ day) has been found to be more effective (penetrates better and achieves larvicidal concentrations) and cheap, and is fast replacing other drugs. Stools should be rechecked in 3 months. For cysticercosis, systemic removal of the cyst is recommended whenever possible. Destruction of the cysts in cerebral cysticercosis by anticysticercals may induce severe side effects from an inflammatory response. Corticosteroids (1.5 mg/ kg/ day) are used in these cases. Niclosamide (2 g) is another drug used. Old dead cysts are left as such. Asymptomatic subcutaneous nodules do not require treatment.

17. The best course is the removal of the cyst by surgery. As with intraocular cysticercosis, it would be better that the orbital cysts are removed/ extrude out than be killed inside. However, surgery for orbital myocysticercosis is fraught with complications as it may damage important orbital structures because the cyst is adherent to the surrounding structures from inflammatory reaction, and is best avoided. Corticosteroids and anti-inflammatory drugs are given to suppress the inflammation. Recently, cysticidal drugs such as albendazole (200-400 mg twice daily for one month) and praziquantel have been given to kill the parasite with good results, confirmed by USG. We have noticed that the cysticerci of the extraocular muscles travel forward, come to lie in a subconjunctival location and then extrude out spontaneously. We have adopted a policy to wait and watch in these cases. We avoid giving steroids and antihelminthics as these suppress inflammation and delay the movement of the cyst outward, and hence, its extrusion.

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