Visual field defects in neurocysticercosis: A rare presentation

INTRODUCTION

Neurocysticercosis is one of the commonest helminthic infections which affects central nervous system in humans and is caused by a tapeworm, Taenia solium. It is endemic in developing countries where poverty, unhealthy living conditions, and illiteracy are predominant.^[1] Ocular manifestations of neurocysticercosis include proptosis, extraocular movement restrictions, internuclear ophthalmoplegia, orbital cellulitis, strabismus, ptosis, intraocular cyst, optic disc edema, retinal detachment, and vitreous hemorrhages.^[2-6] Here, we report a rare case of neurocysticercosis presenting with visual field defects and its management.

CASE REPORT

A 46-year-old male patient reported with complaint of restricted visual field in the left eye for one week. His best-corrected visual acuity was 6/6p, N6 in both eyes, and color vision was normal. Intraocular pressure was 16 mm Hg in both eyes. Extraocular movements were full, free, and painless in all positions of gaze. The anterior segment revealed posterior polar cataract in both eyes. Pupils were round, regular, and reacting to light. Fundus examination showed attached retina with lasered lattice degeneration in both eyes. Optical coherence tomography of the macula was normal in both eyes [Figure 1]. On confrontation test, restriction in the outer limits of the visual field in the left side was noted. Perimetry confirmed left homonymous hemianopia [Figure 2].

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Figure 1:

Fundus photo (Left) and optical coherence tomography (Right) of right (Top) and left (Bottom) eye.

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Figure 2:

Perimetry report showing left homonymous hemianopia in both eyes.

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The patient was advised magnetic resonance imaging (MRI) brain + orbit where MRI brain revealed a few peripheral enhancing nodular lesions in the right occipital lobe (11 mm), largest measuring 13 × 12 × 7 mm and appearing as hypointense in T1 and isointense on fluid-attenuated inversion recovery with moderate perilesional edema [Figure 3a]. MRI orbit revealed prominence of peri-optic cerebrospinal fluid sleeves on both sides with partially empty sella. The patient was referred to neurophysician for further management where fluorodeoxyglucose positron emission tomography scan was done which revealed low-grade ring enhancing lesion (8 mm) with mild perilesional edema [Figure 3b]. A diagnosis of neurocysticercosis was made. Stool examination was normal with no larva seen. The patient was started on tablet Prednisolone 50 mg for 5 days and was gradually tapered over one month, tablet Albendazole 400 mg thrice a day for 21 days, and tablet Brivaracetam 50 mg twice a day for 60 days.

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Figure 3:

(a) Magnetic resonance imaging brain and (b) fluorodeoxyglucose positron emission tomography scan illustrating neurocysticercosis. The black arrow shows cystic lesion.

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At one month, MRI brain was repeated which showed resolving nodular lesion (3 mm) and reduced edema. Perimetry revealed significant improvement in the visual field defect [Figure 4]. The patient was continued on tablet Brivaracetam 50 mg twice a day by the neurophysician.

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Figure 4:

Perimetry report showing improvement in visual field defect in both eyes.

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DISCUSSION

Neurocysticercosis is a rare condition with an incidence ranging from 0.1% to 6% in Asian countries.^[7] It is caused by a tapeworm , T. solium. Cysticercus, the larval form houses in humans and pigs who are the intermediate hosts whereas humans are definitive host for the adult tapeworm. When humans ingest uncooked infected pork, cysticerci get released by digestive enzymes and their scolices evaginate the intestinal wall where they multiply to form adult tapeworm.^[1]

Seizure is the most common initial presentation seen in patients with neurocysticercosis.^[8] In chronic cases, focal neurological signs can also be seen which are similar to brain tumor or tuberculomas with focal granulomatous etiology.^[9] Acute stroke syndrome is also noted in few cases of neurocysticercosis.^[10] The most common ocular symptoms include diplopia, decreased vision, redness, pain, and photophobia.^[11] Lesion involving the optic nerve pathway in parietal, temporal, or occipital lobe can cause visual field defects or diminution of vision.^[12]

The treatment modalities for neurocysticercosis include antiepileptics, corticosteroid, anthelmintic, and surgical interventions.^[13] To the best of our knowledge, there is limited literature reporting visual field defects in cases of neurocysticercosis.^[14-16] In our case, visual field defect was the initial presenting symptom. We noted improvement in the visual field defect following medical management which is in agreement with previous report by Besada et al.^[15] Another study by Vaitheeswaran et al. has also reported improvement in visual fields post-orbitotomy which was carried out to remove optic nerve cysticercosis.^[16]

CONCLUSION

Ophthalmic manifestations of neurocysticercosis are variable and may include rare symptoms like visual field defects. A multimodal imaging and multidisciplinary approach can be helpful in early diagnosis and faster recovery in patients with neurocysticercosis.