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Show PHOTO ESSAY Optic Neuropathy and Sixth Cranial Nerve Palsy Caused by Compression From a Dolichoectatic Basilar Artery Jack Yu- Shih Lin, MD, Szu- Yuan Lin, MD, Joseph I- Chieh Wu, MD, and I- Hua Wang, MD FIG. 1. A. Postcontrast T1 coronal MRI at the level of the optic chiasm does not show the optic chiasm because it is thinned and displaced superiorly by an ectatic basilar artery ( arrow). B. Postcontrast T1 sagittal MRI at the level of the pituitary fossa shows an ectatic basilar artery causing compression and rostral displacement of the right optic nerve ( bent arrow) before it merges with the optic chiasm. The proximal portion of the ectatic basilar artery flattens the brainstem at the pontomedullary junction ( straight arrow). C. Postcontrast T1 axial MRI at the level of the pons shows the right pons being compressed by a tortuous basilar artery ( arrow). Abstract: A 53 - year- old man with progressive visual loss in the right eye and diplopia manifested dysfunction of the right optic nerve and the right sixth cranial nerve. MRI revealed a markedly enlarged and tortuous basilar artery, its proximal portion compressing the right sixth cranial nerve at the exit from the pons and its distal portion elevating and compressing the right optic nerve. This is the first report of optic neuropathy and sixth cranial nerve palsy caused by a dolichoectatic basilar artery. (/ Neuro- Ophthalmol 2006; 26: 190- 191) Department of Ophthalmology ( JY- SL, S- YL, JI- CW, I- HW), Cathay General Hospital, Taipei, Taiwan; and the Department of Ophthalmology ( JY- SL), Taipei Municipal Wan- Fang Hospital, Taipei, Taiwan. Address correspondence to I- Hua Wang, MD, 15th Kuang- Fu Street, Yung- He City, Taipei Hsien, Taiwan; E- mail: jackyulin@ yahoo. com A53- year- old man presented with progressive loss of vision in the right eye and recent diplopia. His medical history was significant for hypertension and two strokes. Best- corrected visual acuity was finger counting in the right eye and 20/ 60 in the left eye. The patient identified zero of 13 Ishihara plates with the right eye and 13 of 13 plates with the left eye. Visual field examination revealed a dense field defect in the right eye and peripheral constriction and generalized depression in the left eye. There were no ocular adnexal abnormalities. Pupils were equal in size but a relative afferent pupillary defect was present in the right eye. Right abduction was 60% of normal. He had a right esotropia of 40 prism diopters. Slit lamp biomicroscopy revealed moderate cortical nuclear cataract in the left eye consistent with 20/ 60 visual acuity. Funduscopy revealed bilateral retinal arterial narrowing and deflections of veins at the arteriovenous crossing consistent with grade 2 hypertensive retinopathy. A diffusely pale disc in the right eye and a normal optic disc in the left eye were also found. 190 J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 Dolichoectatic Basilar Artery J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 MRI revealed a tortuous vertebrobasilar artery dilated up to 8 mm in diameter, its proximal dolichoectatic portion compressing the right pons ( Fig. 1) and its distal portion compressing and upwardly displacing the right optic nerve ( Fig. 1). Rigorous control of hypertension was recommended. On a follow- up visit 18 months later, there were no significant changes in his vision or ocular motility. Vertebrobasilar dohchoectasia refers to the elongation and distension of the vertebrobasilar system. Ectasia is diagnosed when the diameter of the basilar artery is greater than 4.5 mm ( 1). It can lead to multiple neurologic dysfunctions by compression of adjacent tissue, including the cranial nerves, with the trigeminal and facial nerves being the most frequently affected ( 2). Sixth cranial nerve palsy, either isolated or combined with other neurologic deficits, has been reported ( 3,4). Compression of the visual pathway is rare with only one reported case ( 5). To our knowledge, the combination of sixth cranial nerve palsy and optic neuropathy has not been reported. It is of interest that despite dohchoectasia of such magnitude, our patient had no other neurologic deficits. REFERENCES 1. Smoker WR, Corbett JJ, Gentry LR, et al. High- resolution computed tomography of the basilar artery: 2. Vertebrobasilar dohchoectasia: clinical- pathologic correlation and review. AJNR Am J Neuroradiol 1986; 7: 61- 72. 2. Ohtsuka K, Sone A, Igarashi Y, et al. Vascular compressive abdu-cens nerve palsy disclosed by magnetic resonance imaging. Am J Ophthalmol 1996; 122: 416- 9. 3. Goldenberg- Cohen N, Miller NR. Noninvasive neuroimaging of basilar artery dohchoectasia in a patient with an isolated abducens nerve paresis. Am J Ophthalmol 2004; 137: 365- 7. 4. Zhu Y, Thulborn K, Curnyn K, et al. Sixth cranial nerve palsy caused by compression from a dolichoectatic vertebral artery. J Neuro-ophthalmol 2005; 25: 134- 5. 5. Guirgis MF, Lam BL, Falcone SF Optic tract compression from dolichoectatic basilar artery. Am J Ophthalmol 2001; 132: 283- 6. 191 |
