Occipital neurocysticercosis presenting as monocular visual hallucinations and transient blurring of vision.

Sir,

Cysticercosis is the most common parasitic infestation of the central nervous system world-wide. It is caused by the ingestion of the eggs of the tapeworm Taenia solium, found in faecally contaminated water and food, spreading hematogenously to various sites of the body.[1] Sufferers often experience a long asymptomatic period, and can present with a variety of neurological manifestations, including, focal neurological deficits, migraines, visual hallucinations, and seizures.[2] Extra-neurological manifestations include, ocular deposition, skeletal muscle nodules, and granulomatous lesions in various soft-tissues. Here, we report a case of occipital neurocysticercosis presenting with visual hallucinations and transient blurred vision as presenting symptoms.

A male patient of age 45 years came to the out-patient Department of Ophthalmology with complaints of occasional mono-ocular blurring of vision, with patient experiencing flashes of light and loss of inferior field of vision in right eye occasionally. His symptoms were not associated with headache or vomiting. On examination, his uncorrected visual acuity was 6/6 in with normal color vision and fundus in both eyes. His visual field examination was normal in both eyes.

On further investigation, Carotid Doppler study of neck vessels was normal on both sides. Magnetic resonance imaging (MRI) of brain showed a well-defined thin walled cystic lesion of size 9 mm × 8 mm with perilesional edema in left medial occipital lobe, which shows fluid intensity on all pulse sequences. On contrast enhanced MRI, the lesion showed rim enhancement. There is an eccentric nodule within the cyst, which is likely to represent scolex [Figures 1–3]. Based on these findings, the diagnosis of neurocysticercosis was made and the patient's symptoms were interpreted as visual seizure. The patient was given oral albendazole in a dosage of 15 mg/kg/day for 2 weeks and systemic steroids in a dosage of 1 mg/kg/day for 2 weeks. Antiepileptic drugs were prescribed. The patient became completely free of symptoms when he came for follow-up after 6 months. Repeat computed tomography (CT) brain was performed, which showed complete resolution of lesion [Figure 4].

Figure 1

Magnetic resonance imaging of brain T1W image showing a cerebrospinal fluidintensity cyst in left occipital lobe

Figure 3

Magnetic resonance imaging of brain with contrast showing rim enhancement of the occipital cyst with an eccentric nodule representing scolex

Figure 4

Post-treatment computed tomography (after 6 months) showing complete resolution of occipital lesion

Magnetic resonance imaging of brain fluid attenuation inversion recovery sequence image showing the cyst with perilesional edema in left occipital lobe

A single ring enhancing lesion is the most common imaging abnormality of neurocysticercosis in Indian patients. The presence of scolex is the absolute diagnostic criterion.[3] Symptoms and signs are related both to parasite and inflammatory immunological response. This is the most common infective cause of seizures in endemic areas and if the lesion is located in the occipital lobe, visual hallucinations may be the only ictal manifestations. However, more frequently visual manifestations precede motor convulsions. These visual phenomena in occipital seizures may simulate migraine with aura. However, the visual hallucinations in seizures are brief, always unilateral (contralateral to lesion) and are not followed by severe headache as in migraine. Most interesting feature of single cysticercus granuloma is spontaneous disappearance within a few weeks, although occasionally it may calcify. These patients only need anti-epileptic therapy, which may be safely withdrawn after CT lesions have disappeared or symptoms have subsided.[3] Although albendazole is generally used in these patients, there is a controversy regarding its role in treatment.[4] The patient will need repeat imaging after several months to ensure complete eradication.

This case emphasizes the need of imaging in patients with atypical visual symptoms having normal intra ocular findings.