|Year : 2019 | Volume
| Issue : 2 | Page : 114-116
Suprasellar cysticercosis cyst with optic nerve compression masquerading as an arachnoid cyst
Aaron Musara1, Nyarai Soko2, Sharai Shamu3
1 Department of Surgery, Neurosurgery Unit, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
2 Harare Eye, Ear, Nose and Throat Institute, Harare, Zimbabwe
3 Harare, Eye, Ear, Nose and Throat Institute, Harare, Zimbabwe
|Date of Web Publication||26-Aug-2019|
Dr. Sharai Shamu
Harare Eye, Ear, Nose and Throat Institute, 5 Weale Road, Milton Park, Harare
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Cysticercosis is a parasitic infection caused by the larvae of the cestode Taenia solium. Ocular parasitosis in humans is well recognized; however, cysticercosis of the optic nerve is rare. Here, we report a case of an adult male who presented with right-sided headache and a gradual loss of vision in the right eye. Optical coherence tomography indicated severe loss of ganglion cells in the right eye. Magnetic resonance imaging showed a predominantly suprasellar cystic lesion thought to represent an arachnoid cyst. We performed a craniotomy to excise the cyst. Histopathological examination of the excised cyst revealed internal living larvae of T. soilum. After co-administration of praziquantel and albendazole, vision was restored, and the headaches ceased. Vision has since been restored in both eyes. A higher degree of neurocysticercosis suspicion should be maintained for patients living in endemic areas who present with ophthalmic symptoms where the brain scans show cystic lesions.
Keywords: Africa, arachnoid cyst, cysticercosis, optic nerve, Zimbabwe
|How to cite this article:|
Musara A, Soko N, Shamu S. Suprasellar cysticercosis cyst with optic nerve compression masquerading as an arachnoid cyst. Middle East Afr J Ophthalmol 2019;26:114-6
|How to cite this URL:|
Musara A, Soko N, Shamu S. Suprasellar cysticercosis cyst with optic nerve compression masquerading as an arachnoid cyst. Middle East Afr J Ophthalmol [serial online] 2019 [cited 2020 Sep 30];26:114-6. Available from: http://www.meajo.org/text.asp?2019/26/2/114/265363
| Introduction|| |
Cysticercosis is a parasitic infection caused by Cysticercus cellulosae, the larval form of the cestode Taenia solium. Infection is often asymptomatic although neurological symptoms such as seizures are common. Ocular involvement is well recognized and involves orbital, intraocular, subretinal, and optic nerve lesions. Optic nerve cysticercosis, in particular, is a rare entity. Despite ocular parasitism being endemic in African populations, the reported prevalence of T. solium taenosis and cysticercosis in African countries is neither extensive nor is up-to-date prevalence data readily available. We report a rare case of suprasellar cysticercosis with compression of the optic nerve in a male patient residing in Zimbabwe, Africa.
| Case Report|| |
A 35-year-old male was referred to our clinic with a 2-week history of right-sided headache and gradual loss of vision in the right eye. The headache was mainly right frontal, with the pain radiating into the right eye. Uncorrected visual acuity was 0.5 in the right eye and 1.0 in the left eye. Best-corrected visual acuity in the right eye was 0.8. There was no afferent pupillary defect, and color vision was normal. Visual fields (VFs) were within the normal limits. Fundoscopy showed a cup–disc ratio of 0.8 in the right eye and 0.6 in the left eye. Optical coherence tomography (OCT) indicated severe loss of ganglion cells restricted to the upper half of the ganglion cell analysis of the right eye [Figure 1].
|Figure 1: Results for a 35-year-old male with a 2-week history of right-sided headache and gradual vision loss. Visual fields presurgery were within the normal limits. Presurgery analysis of ganglion cells shows severe loss of ganglion cells restricted to the upper half of the right eye|
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Magnetic resonance imaging (MRI) revealed a predominantly suprasellar well-circumscribed cystic lesion initially thought to represent a remnant of Rathke's pouch or an arachnoid cyst at this site [Figure 2] The cystic mass appeared to have mass effect on the optic chiasm and was more to the right side. Pituitary function tests showed normal hormonal function. The patient was taken to the operating theatre where a craniotomy was done to surgically excise the cystic mass. A cystic tissue of 21 mm in diameter was removed, and histological examination revealed an internal living C. cellulosae larva. Treatment consisted of 2400 mg praziquantel once daily for 10 days co-administered with 400 mg once-daily albendazole for 3 days and 30 mg prednisolone once daily for 14 days. On discharge from the hospital, a remarkable improvement in vision had been obtained. Uncorrected visual acuity was 1.0 in both eyes 3 months postsurgery. He now no longer has headaches.
|Figure 2: Magnetic resonance imaging scan (T1 coronal and T2 saggital) showing a well-defined suprasellar cyst|
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| Discussion|| |
In this case, we report a male patient who presented with pain accompanied by mild vision loss in the right eye. Examination revealed subtle visual findings indicating vision loss, which were more marked in the right eye. Eye function testing using VF was normal. However, OCT showed structural loss of ganglion cells in the right eye. The increased sensitivity of OCT over VF confirms earlier reports  that a substantial loss of retinal nerve fiber layer may be required before functional loss is detectable using VF. Therefore, from a clinical perspective, structural analysis of the optic nerve using methods such as OCT appears more indicative of early loss of optic nerve function. Suspecting optic nerve function loss, we performed MRI which pointed to possible arachnoid cyst or Rathke's pouch. Following excision of the cyst, histopathology revealed internal living cysticercus larvae. Hence, a diagnosis of neurocysticercosis was made.
Neurocysticercosis, which refers to the central nervous system infection by C. cellulosae, is the most frequent helminthic disease of the central nervous system. It is endemic in developing countries, and it is frequently diagnosed in immigrant populations in the developed countries. Neurocysticercosis in humans is acquired after the ingestion of T. solium ova in fecally contaminated food or water. Ingested eggs hatch into larvae. The larvae cross the intestinal mucosa and move through the bloodstream to preferred organs, which are mainly the brain and skeletal muscles. Common encystment sites include the subcutaneous tissue, the brain, and the eyes. Within the eye, 35% of the cysts are found in the subretinal space, 22% in the vitreous, 22% in the subconjunctival space, 5% in the anterior segment, and only 1% in the orbit. Although optic nerve cysticercosis has been described, it remains a rare form of cysticercosis.
Neurocysticercosis has been described almost everywhere in the central nervous system. Yet, it is rarely described in the sellar or suprasellar region. Suprasellar cysticercosis is known to cause visual loss through chiasmal involvement as it can cause inflammation and compression from the adjacent cysts. Retrochiasmal damage caused by large parenchymal cysts or vasculitis-mediated cerebral infarction also contributes to vision loss. Compression of the optic nerve led to loss of vision in our patient. Compression was more on the right side resulting in loss of vision in the right eye than the left eye. Removal of the cyst resulted in improvement in vision. However, OCT remained unchanged, and VFs appeared to worsen postsurgery. This could infer no further trauma to ganglion cells from the removal of the encapsulated lesion. This could be a case of structure–function discordance  as self-reported vision improved postsurgery.
Worldwide, neurocysticercosis is estimated to cause 50,000 deaths per annum  and has been described as an emerging yet neglected tropical disease in sub-Saharan Africa where it is estimated to have a prevalence of 10% in humans. The reported cases of T. solium cysticercosis in Africa, however, remain underreported and underinvestigated despite increased infection owing to increased pork production and subsequent consumption. It is, therefore, imperative for health-care workers in African countries to have a higher degree of suspicion of cysticercosis, accompanied by an increased output in reported cases and research of this neglected zoonotic parasitosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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