Fourth Nerve Palsy Due to Neurocysticercosis

Neurocysticercosis is the most common disease of the nervous system caused by a parasite. Ophthalmological manifestations of cysticercosis typically are due to direct intraorbital or intraocular involvement, parenchymal brainstem involvement, or secondary to hydrocephalus or increased intracranial pressure. We describe a patient with a unilateral fourth nerve palsy, a rare presentation of neurocyticercosis.

Photo Essay Section Editors: Melissa W. Ko, MD Dean M. Cestari, MD Peter Quiros, MD Fourth Nerve Palsy Due to Neurocysticercosis Bennett Yau-Bun Hong, MD, Andrew Bean, BS, Aroucha Vickers, DO, Matthew Cykowski, MD, Andrew G. Lee, MD FIG. 1. Pretreatment axial fluid-attenuated inversion recovery MRI (A) shows enlargement of the cerebral aqueduct (arrow), while postcontrast axial T1 scan (B) reveals a cystic lesion (arrowheads) extending into the left cerebromedullary cistern (cisterna magna). Abstract: Neurocysticercosis is the most common disease of the nervous system caused by a parasite. Ophthalmological manifestations of cysticercosis typically are due to direct intraorbital or intraocular involvement, parenchymal brainstem involvement, or secondary to hydrocephalus or increased intracranial pressure. We describe a patient with a unilateral fourth nerve palsy, a rare presentation of neurocyticercosis. Journal of Neuro-Ophthalmology 2020;40:414-416 doi: 10.1097/WNO.0000000000000785 © 2019 by North American Neuro-Ophthalmology Society Department of Ophthalmology (BY-BH, AGL), The University of Texas Medical Branch, Galveston, Texas; McGovern Medical School (AB), Houston, Texas; Department of Ophthalmology (AV, AGL), Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas; Department of Pathology and Genomic Medicine (MC), Houston Methodist Hospital, Houston, Texas; Baylor College of Medicine (AGL), Houston, Texas; Department of Ophthalmology, Neurology, and Neurosurgery (AGL), Weill Cornell Medicine, New York, New York; Division of Ophthalmology (AGL), The University of Texas Maryland Anderson Cancer Center, Houston Texas; Department of Ophthalmology (AGL), The University of Iowa Hospitals and Clinics, Iowa City, Iowa; and Department of Ophthalmology (AGL), Texas A and M College of Medicine, Temple, Texas. The authors report no conflicts of interest. Address correspondence to Andrew G. Lee, MD, Houston Methodist Hospital, Blanton Eye Institute, 6560 Fannin Street #450, Houston, TX 77030; E-mail: [e-mail] 414 A 36-year-old man who made frequent trips to El Salvador was evaluated in the emergency department with a year long history of frontal headaches and progressive nausea, dizziness, fatigue, weakness, imbalance, occasional tinnitus, and blurry vision. In addition to multiple cerebral calcifications, neuroimaging demonstrated obstructive hydrocephalus at the level of the cerebral aqueduct and a cystic lesion that extended through the left foramen of Luschka and into the left cerebellomedullary cistern (Fig. 1). To relieve the hydrocephalus, the patient underwent a right frontal burr hole endoscopic third ventriculostomy (ETV) with fenestration of the septum pellucidum and placement of an external ventricular drain. Then, he began a course of dexamethasone 4 mg by mouth twice a day and empiric praziquantel 1,500 mg by mouth three times a day for presumed neurocysticercosis. Cerebrospinal fluid (CSF) analysis showed lymphocyticpredominant pleocytosis-19 white cells (76% lymphocytes) -and was positive for anticysticercosis IgG. Antibody titers were also elevated, at 0.60 optical density. Over the next 4 days, the patient experienced symptomatic relief. The drain was removed and the patient was discharged from the hospital. Despite completing a 4-week course of praziquantel and dexamethasone, the patient's headaches worsened, and he developed binocular diplopia. On examination, the anterior and posterior segments of each eye were normal. He had Hong et al: J Neuro-Ophthalmol 2020; 40: 414-416 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay FIG. 2. After medical treatment, axial fluid-attenuated inversion recovery image (A) demonstrates the cerebral aqueduct, while postcontrast axial T1 scan (B) reveals a cystic lesion. The photograph (B) shows reduction in size of the cystic lesion (9-7 mm) (arrowheads) and enhancement of the cyst wall and cerebral aqueduct. a right head tilt. Ocular motility examination revealed mild underaction of the left superior oblique muscle and a left hypertropia of 5 prism diopters that was worse in right gaze and left head tilt. Double Maddox rod testing detected 5° of excyclotorsion of the left eye. Following initial progress, follow-up MRI showed that the cyst had stopped involuting (Fig. 2). Repeat serum cysticercosis antibody titer was increased at 1.0 optical density. Two months later, the cyst was resected through a left far-lateral transcondylar suboccipital craniotomy with microsurgical fenestration. Pathology showed predominantly nonviable necrotic racemose cysticercosis and chronic inflammation (Fig. 3). Over the following 2 weeks, the patient completed a course of dexamethasone and albendazole. Repeat MRI showed no evidence of recurrent disease. Four months later, the patient's ocular motility was normal, and he experienced full resolution of his headaches and diplopia. Neurocysticercosis (NCC) is the most common parasitic human central nervous system disease. While most cases are found in the developing world, between 1,320 and 5,050 new cases of NCC occur every year in the United States (1). Most symptoms of NCC include seizures, headaches, and focal neurological deficits. Only 6% of patients have visionrelated complaints (2). The infection begins with fecal-oral transmission of Taenia solium eggs that hatch into larvae capable of hematogenous dissemination. Live cysts evade the host immune response and are rarely symptomatic. However, on degeneration, an inflammatory response results from the sudden release of antigens, disrupting the blood-brain barrier leading to brain injury (3). Stages of cyst degeneration can be detected on MRI. Viable cysts are hypointense on T1 and fluid-attenuated inversion recovery (FLAIR) sequences. Over time, cysts turn opaque, becoming hyperintense on FLAIR with surrounding FIG. 3. Pathology of cysticercus cyst. A. The cyst wall (arrows) is nonviable and necrotic, and a foreign-body giant cell (arrowhead) is present (hematoxylin and eosin, ·200). B. The cyst wall is composed of cellular (arrows) and cuticular (arrowheads) layers (hematoxylin and eosin, ·400). Hong et al: J Neuro-Ophthalmol 2020; 40: 414-416 415 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay dense enhancement on T1. Ultimately, calcification occurs. Before antihelminthic treatment of our patient, the viable cystic lesion was hypointense on T1. By 1 month, the cyst involuted and had cyst wall enhancement. The MRI of our patient did not reveal a parenchyma lesion, instead showing a dilated cerebral aqueduct caused by an obstructive hydrocephalus. The fourth nerve nuclei lie beneath the aqueduct. Thus, expansion of the cyst could have produced a mass effect on the nuclei leading to a fourth nerve palsy. However, the patient began complaining of diplopia during resolution of hydrocephalus after initiation of antiparasitic treatment. This suggests an inflammatory etiology secondary to cyst degeneration. ETV-related diplopia also was considered, but no direct injury was seen radiographically in the area of the fourth nerve. In addition, diplopia after ETV typically occurs in the immediate postoperative period and not after several weeks. The management of a patient with neurocysticercosis varies according to the location of the cysts, stage of cyst degeneration, and symptoms. In the setting of acute hydrocephalus from extraparenchymal infection, relief with CSF drainage or shunt placement is indicated, as in our patient. In general, antihelminthic treatment is followed by adjunctive steroids (4). Access to intraventricular cysts is more favorable compared with those located within brain 416 parenchyma. Therefore, surgical removal of cystic lesions is determined on a case-by-case basis. STATEMENT OF AUTHORSHIP Category 1: a. conception and design: A. G. Lee, B. Y.-B. Hong, and A. Vickers; b. acquisition of data: B. Y.-B. Hong, A. Bean, and M. Cykowski; c. analysis and interpretation of data: B. Y.-B. Hong, A. Bean, A. Vickers, M. Cykowski, and A. G. Lee. Category 2: a. drafting the manuscript: B. Y.-B. Hong and A. Bean; b. revising it for intellectual content: A. Vickers and A. G. Lee. Category 3: a. final approval of the completed manuscript: A. G. Lee. REFERENCES 1. Serpa JA, White AC. Neurocysticercosis in the United States. Pathog Glob Health. 2012;106:256-260. 2. Sotelo J, Guerrero V, Rubio F. Neurocysticercosis: a new classification based on active and inactive forms. A study of 753 cases. Arch Intern Med. 1985;145:4420445. 3. Guerra-Giraldez C, Marzal M, Cangalaya C, Balboa D, Orrego MA, Paredes A, Gonzales-Gustavson E, Arroo G, Garcia HH, Gonzalez AE, Manhanty S, Nash TE; Cysticercosis Working Group in Peru. Disruption of the blood-brain barrier in pigs naturally infected with taenia solium, untreated and after anthelmintic treatment. Exp Parasitol. 2013;134:443-446. 4. Garcia HH, Nash TE, Brutto OH. Clinical symptoms, diagnosis and treatment of neurocysticercosis. Lancet Neurol. 2013;13:1202-1215. Hong et al: J Neuro-Ophthalmol 2020; 40: 414-416 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.