Vertebrobasilar Dolichoectasia Causing An Optic Tract Syndrome

Photo Essay Section Editor: Timothy J. McCulley, MD Vertebrobasilar Dolichoectasia Causing An Optic Tract Syndrome Brandon B. Holmes, BA, Wesley C. Green, MD, Nathan H. Kung, MD, Joel A. Goebel, MD, Gregory P. Van Stavern, MD FIG. 1. Kinetic perimetry reveals an incongruous left homonymous inferior quadrantanopia. OD, right eye; OS, left eye. Abstract: Vertebrobasilar dolichoectasia (VBD) is characterized by significant dilation, elongation, and tortuosity of the vertebrobasilar system. We present a unique case of VBD, confirmed by neuroimaging studies, showing vascular compression of the right optic tract and lower cranial nerves leading to an incongruous left homonymous inferior quadrantanopia and glossopharyngeal neuralgia. Journal of Neuro-Ophthalmology 2017;37:179-181 doi: 10.1097/WNO.0000000000000495 © 2017 by North American Neuro-Ophthalmology Society A n 81-year-old man was referred for neuro-ophthalmic evaluation after an incongruous left inferior quadrantanopia was incidentally discovered during a yearly eye examination. He was visually asymptomatic and denied a history of headache, Medical Scientist Training Program (BBH), Washington University School of Medicine, St. Louis, Missouri; and Departments of Ophthalmology and Visual Sciences (WCG, NHK, GPVS) and Otolaryngology-Head & Neck Surgery (JAG), Washington University, St. Louis, Missouri. The authors report no conflicts of interest. Address correspondence to Gregory P. Van Stavern, MD, Department of Ophthalmology and Visual Sciences, 660 South Euclid Avenue, Campus Box 8096, St. Louis, MO 63110; E-mail: [e-mail] Holmes et al: J Neuro-Ophthalmol 2017; 37: 179-181 transient visual loss, or stroke. He had well-controlled hypertension on irbesartan and a 9-year history of glossopharyngeal neuralgia for which he was taking gabapentin. On examination, visual acuity was 20/25 in each eye. Pupils were equal, round, and reactive to light without a relative afferent pupillary defect. Extraocular movements were full, and slit-lamp examination, with measurement of intraocular pressures, was normal. An incongruous left homonymous visual field defect was found on kinetic perimetry (Fig. 1). Ophthalmoscopy revealed mild bilateral optic disc pallor with a cup-to-disc ratio of 0.7. Audiometry showed high-frequency sensorineural hearing loss, more pronounced in the left ear, with decreased speech discrimination in the same ear. MRI of the brain revealed a dilated and tortuous (dolichoectatic) basilar artery that protruded into the suprasellar cistern and abutted and elevated the right aspect of the optic chiasm and right optic tract (Fig. 2A, B). In addition, the tortuous left vertebral artery and basilar artery caused displacement of the lower brainstem and cranial nerves (Fig. 2C, D). These radiographic results accounted for the patient's visual field loss and glossopharyngeal neuralgia. Taken together, these clinical and neuroimaging findings confirmed a diagnosis of vertebrobasilar dolichoectasia (VBD). Cerebrovascular dolichoectasia is a disorder characterized by dilated, elongated, and tortuous cerebral arteries. When 179 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay FIG. 2. Axial brain MRI. A and B. Precontrast T1 imaging shows a dilated and elongated basilar artery (arrowhead) compressing the right optic tract (arrow). C and D. Postcontrast T1 study reveals an ectatic basilar artery (arrowhead) compressing the medulla and the cerebellum and traversing across the lower cranial nerves. present in the vertebrobasilar system, it is termed VBD and accounts for approximately 80% of cases (1-3). The pathophysiology of VBD is incompletely understood. Causative defects within the tunica media have been proposed, related either to extracellular matrix impairment in the setting of atherosclerotic risk factors or metalloproteinase imbalance, or to smooth muscle cell impairment in the setting of lysosomal storage abnormalities. The disease is often not limited to cerebral vasculature but can occur simultaneously in the aorta, leading to aortic aneurysm or ectasia (3,4). The clinical manifestations of these aberrant vessels are generally divided into compressive symptoms and vascular events. Compressive symptoms result from mass effect of the dilated vessels on cranial nerves and the brainstem. Because of anatomic proximity, dolichoectasia of the vertebrobasilar system most frequently affects cranial nerves V, VII, VIII, and IX, which can manifest as trigeminal neuralgia, hemifacial spasm, hearing loss, glossopharyngeal neuralgia, or dysphagia (1,5). Vascular events, typically, are characterized by transient ischemic attack, ischemic stroke, or intracerebral hemorrhage, occurring in the region of the dolichoectatic artery (1). Rare cases of visual loss due to compression of optic nerves, chiasm, or tracts also have been 180 reported (6-10), including one which required microvascular decompression (9). Other neurovascular compression syndromes, such as those caused by aneurysms, can result in vision loss from compression of the anterior visual pathways (11). The most commonly reported cases are from large aneurysms of the paraclinoid or supraclinoid segments of the internal carotid artery (11,12). These cases often involve aneurysms 15-30 mm in size, with the visual loss being ascribed to direct neural compression by the aneurysm, compression of the optic nerve against the anterior optic canal or, in some instances, disruption of the vascular supply to the eye (13,14). The diagnostic criteria for VBD initially were proposed by Smoker and colleagues (15,16) using computed tomographic angiography and were based on quantitative metrics for tortuosity and elongation, along with a basilar artery diameter of .4.5 mm. Our patient's basilar artery diameter was approximately 8 mm, had lateral deviation extending into the cerebellopontine angle cistern, and a bifurcation which indented and elevated the floor of the third ventricle. To date, our patient remains asymptomatic from his visual field defect, and his glossopharyngeal neuralgia is Holmes et al: J Neuro-Ophthalmol 2017; 37: 179-181 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay well-controlled on medication. Surgical intervention would only be considered with progressive neurological deficits. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern; b. Acquisition of data: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern; c. Analysis and interpretation of data: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern. Category 2: a. Drafting the manuscript: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern; b. Revising it for intellectual content: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern. Category 3: a. Final approval of the completed manuscript: B. B. Holmes, W. C. Green, N. H. Kung, J. A. Goebel, and G. P. Van Stavern. REFERENCES 1. Yuan YJ, Xu K, Luo Q, Yu JL. 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Intracranial Displacement of the Eye After Blunt Trauma: Retraction In the December 2009 issue of the Journal of Neuro-Ophthalmology, the article "Intracranial Displacement of the Eye After Blunt Trauma" appearing on page 311 is retracted. Upon the advice of the Deputy Director of Research Affairs at Tabriz University of Medical Science, Tehran, Iran the journal has decided to retract the paper on the following grounds: Following an investigation by Tabriz University, it was determined by that institution that "None of the authors of [the] paper had direct scientific or treatment link to the reported case." The doctors actually involved in the original patient treatment brought the ethical breach to the attention of Tabriz University. Following a thorough investigation at Tabriz University it was concluded fraud through inappropriate authorship had been committed. Tabriz University as a consequence of that investigation asked the Journal of Neuro-Ophthalmology to retract the case report published in 2009. REFERENCE Miabi Z, Nezami N, Midia M, Midia R. Intracranial displacement of the eye after blunt trauma. J Neuroophthalmol 2009;29:311 Holmes et al: J Neuro-Ophthalmol 2017; 37: 179-181 181 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.