Unilateral Fourth Nerve Palsy due to Presumed Metastatic Melanoma

An 81-year-old man with a history of metastatic melanoma presented with sudden onset of painless, binocular vertical diplopia. The clinical examination was consistent with a right fourth nerve palsy. An MRI of the head revealed a mass dorsal to the right tectum at the level of the inferior colliculus. An MRI just 4 months prior did not show a lesion in that location. An MRA of the head did not show an aneurysm. This is a rare case of an isolated fourth nerve palsy believed to be due to metastatic melanoma compressing the nerve along the dorsal midbrain

Photo Essay Section Editors: Melissa W. Ko, MD Dean M. Cestari, MD Peter Quiros, MD Unilateral Fourth Nerve Palsy due to Presumed Metastatic Melanoma Joshua Pasol, MD, Eric A. Mellon, MD PhD, Lynn G. Feun, MD, Gaurav M. Saigal, MD, Tejan P. Diwanji, MD, Ricardo J. Komotar, MD Downloaded from http://journals.lww.com/jneuro-ophthalmology by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3i3D0OdRyi7TvSFl4Cf3VC1y0abggQZXdtwnfKZBYtws= on 05/04/2022 FIG. 1. Axial (left) and coronal (right) T1 MRI of the head, with contrast, showed an enhanced lesion dorsal to the right tectum along the right fourth nerve pathway. Abstract: An 81-year-old man with a history of metastatic melanoma presented with sudden onset of painless, binocular vertical diplopia. The clinical examination was consistent with a right fourth nerve palsy. An MRI of the head revealed a mass dorsal to the right tectum at the level of the inferior colliculus. An MRI just 4 months prior did not show a lesion in that location. An MRA of the head did not show an aneurysm. This is a rare case Department of Ophthalmology (JP), University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, Miami, Florida; Department of Radiation Oncology (EAM, TPD), University of Miami Miller School of Medicine, Miami, Florida; Department of Hematology/Oncology (LGF), University of Miami Miller School of Medicine, Miami, Florida; Department of Radiology (GMS), University of Miami Miller School of Medicine, Miami, Florida; Department of Neurosurgery (RJK), University of Miami Miller School of Medicine, Miami, Florida. The authors report no conflicts of interest. Address correspondence to Joshua Pasol, MD; Bascom Palmer Eye Institute, 900 NW 17th Street, Miami, FL 33136 E-mail: jpasol@med. miami.edu e134 of an isolated fourth nerve palsy believed to be due to metastatic melanoma compressing the nerve along the dorsal midbrain. Journal of Neuro-Ophthalmology 2021;41:e134–135 doi: 10.1097/WNO.0000000000000902 © 2020 by North American Neuro-Ophthalmology Society A n 81-year-old man presented with sudden onset of painless, binocular vertical diplopia. He had a history of metastatic melanoma with a single brain metastasis to the left temporal lobe 18 months before presentation. The brain metastasis was removed via craniotomy and treated with 30 Gy in 5 fractions by fractionated stereotactic radiotherapy. The lesion was reported as nearly amelanotic metastatic melanoma. An MRI of the head performed 4 months before presentation did not show any lesion that would cause diplopia. The initial melanoma diagnosis was in 2012 where an Pasol et al: J Neuro-Ophthalmol 2021; 41: e134-e135 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay upper back lesion was removed. Metastatic disease was diagnosed in 2016 after presenting with cough, abnormal chest computed tomography, and fine-needle aspiration which revealed metastatic melanoma and which point nivolumab and ipilimumab therapy was started. This was later switched to pembrolizumab after brain metastasis was diagnosed in 2017. The clinical examination revealed 20/40 vision in both eyes. Confrontation fields were full to finger counting. The pupils were equal, and no rapid afferent pupillary defect was noted. The eye movements showed a 23 depression of the right eye with adduction in the direction of the superior oblique function. Alternate cover testing showed a right hypertropia of 10 diopters on primary gaze, 12 diopters on left gaze, and 6 diopters on right gaze. Right head tilt showed an 8 diopter right hypertropia and left tilt measured 6 diopters of right hypertropia. Excyclotorsion was not assessed. The motility and examination was consistent with a right superior oblique palsy. The funduscopic examination was negative for any suspicious lesions. An MRI of the head with contrast revealed a new enhancing lesion dorsal to the right midbrain at the level of the inferior colliculus (Fig. 1). An MRI 4 months before presentation did not show the present lesion thus concerning for a new metastatic lesion (Fig. 2). An MRA of the head did not show an aneurysm (Fig. 3). Fourth nerve palsies can occur from a host of etiologies. Fourth nerve palsy is most commonly due to microvascular FIG. 3. MRA of the head revealed no aneurysm at the level of the presumed metastatic lesion. ischemia, trauma, and congenital causes (1,2). Other rare etiologies of fourth nerve palsy include benign tumors such as schwannomas and malignant processes such as perineural spread of cancer or tumor metastasis (3–5). In this case, an isolated fourth nerve palsy and a history or metastatic melanoma led to urgent neuroimaging which showed a new lesion at the level of the right fourth nerve. Given the patient age, lesion location, and known history, the patient underwent 15 Gy stereotactic radiosurgery to the lesion. We are unaware of previous reports of isolated fourth nerve palsy due to metastatic melanoma to the fourth nerve. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: n/a, case report; b. Acquisition of data: n/a, case report; c. Analysis and interpretation of data: n/a case report. Category 2: a. Drafting the manuscript: J. Pasol, E. A. Mellon; b. Revising it for intellectual content: n/a. Category 3: a. Final approval of the completed manuscript: J. Pasol, E. A. Mellon, L. G. Feun, G. M. Saigal, T. P. Diwanji, R. J. Komotar. REFERENCES FIG. 2. Axial T1 MRI of the head, with contrast, 4 months before presentation showed lack of pathology along the right fourth nerve. Pasol et al: J Neuro-Ophthalmol 2021; 41: e134-e135 1. Dosunmu EO, Hatt SR, Leske DA, Hodge DO, Holmes JM. Incidence and etiology of presumed fourth cranial nerve palsy: a populationbased study. Am J Ophthalmol. 2018;185:110–114. 2. von Noorden GK, Murray E, Wong SY. Superior oblique paralysis. A review of 270 cases. Arch Ophthalmol. 1986;104:1771–1776. 3. Feinberg AS, Newman NJ. Schwannomas in patients with isolated unilateral trochlear nerve palsy. Am J Oph. 1999;127:183–188. 4. Chang PC, Fischbein NJ, McCalmont TH, Kashani-Sabet M, Zettersten ZM, Liu AY, Weissman JL. Perineural spread of malignant melanoma of the head and neck: clinical and imaging features. Am J Neuroradiol. 2004;25:5–11. 5. Lee SU, Choi JY, Kim HJ, Kim JS. Central trochlear palsy as an isolated finding with metastatic tumor. J Clin Neurol. 2018;14:254–256. e135 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.